5

- i CHAPTER 5. ENGINEERING ANALYSIS

TABLE OF CONTENTS

5.1 INTRODUCTION

................................ ................................ ............................... 5

- 1 5.2 STRUCTURING THE ENGI NEERING ANALYSIS

................................ ........ 5

- 1 5.2.1 Summary of Design Line Coverage

................................ ................................ ..... 5

- 8 5.2.2 Scaling Relationships in Transformer Manufacturing

................................ ....... 5

- 10 5.3 TECHNICAL DESIGN INP UTS

................................ ................................ ...... 5

- 13 5.3.1 A and B Loss Valuation Inputs

................................ ................................ .......... 5

- 14 5.3.2 Core Material Options

................................ ................................ ........................ 5

- 16 5.3.3 Core Configurations

................................ ................................ ........................... 5

- 17 5.3.3.1 Standard Core Configurations

................................ ................................ 5

- 18 5.3.3.2 Symmetric Core Configurations

................................ ............................ 5

- 20 5.3.3.3 Core Deactivation Technology

................................ .............................. 5

- 23 5.3.4 Less

- Flammable Liquid

- Immersed Transformers

................................ ............. 5

- 25 5.3.5 Design Line 1 Representative Unit

................................ ................................ .... 5

- 26 5.3.6 Design Line 2 Representative Unit

................................ ................................ .... 5

- 27 5.3.7 Design Line 3 Representative Unit

................................ ................................ .... 5

- 27 5.3.8 Design Line 4 Representative Unit

................................ ................................ .... 5

- 28 5.3.9 Design Line 5 Representative Unit

................................ ................................ .... 5

- 29 5.3.10 Design Line 6 Representative Unit

................................ ................................ .... 5

- 30 5.3.11 Design Line 7 Representative Unit

................................ ................................ .... 5

- 31 5.3.12 Design Line 8 Representative Unit

................................ ................................ .... 5

- 32 5.3.13 Design Line 9 Representative Unit

................................ ................................ .... 5

- 33 5.3.14 Design Line 10 Representative Unit

................................ ................................ .. 5

- 34 5.3.15 Design Line 11 Representative Unit

................................ ................................ .. 5

- 35 5.3.16 Design Line 12 Representative Unit

................................ ................................ .. 5

- 36 5.3.17 Design Line 13A Representative Unit

................................ ............................... 5

- 37 5.3.18 Design Line 13B Representative Unit

................................ ............................... 5

- 38 5.3.19 Newly Optimized Designs and Previously Optimized Designs

........................ 5

- 38 5.4 MATERIAL AND LABOR I NPUTS

................................ ................................ 5

- 39 5.4.1 Material Prices

................................ ................................ ................................ ... 5

- 41 5.4.2 Material Inputs to the Design Software

– Liquid

- Immersed

............................. 5

- 43 5.4.3 Material Inputs to the Design Software

– Dry

- Type

................................ ......... 5

- 48 5.4.4 Labor Costs

................................ ................................ ................................ ........ 5

- 53 5.5 EFFICIENCY LEVELS

................................ ................................ ..................... 5

- 5 9 5.5.1 Criteria for Selecting Efficiency Levels

................................ ............................ 5

- 60 5.5.2 Efficiency Levels Selected

................................ ................................ ................. 5

- 60 5.6 RESULTS OF THE ANALY SIS ON EACH DESIGN L INE

.......................... 5

- 63 5.6.1 Traditional Core Designs for the Reference Case

................................ .............. 5

- 63 5.6.2 Symmetric Core Designs for the Reference Case

................................ .............. 5

- 77 5.7 3 EXAMPLE TRANSFORMER DESIGNS & COST BREAKDOWNS

......... 5

- 86 5.7.1 Design Details Report for Transformer from Design Line 1

............................. 5

- 87 5.7.2 Design Details Report for Transformer from Design Line 7

............................. 5

- 915

- ii

5.7.3 Design Details Report for Transformer from Design Line 12

........................... 5

- 95

LIST OF TABLES Table 5.2.1 Equipment Classes and Number of kVA Ratings

................................ ........ 5

- 2 Table 5.2.2 Engineering Design Lines (DLs) and Representative Units for Analysis

... 5

- 3 Table 5.2.3 Liquid

- Immersed Design Lines and Representative Units

.......................... 5

- 8 Table 5.2.4 Dry

- Type, Low

- Voltage Design Lines and Representative Units

............... 5

- 9 Table 5.2.5 Dry

- Type, Medium

- Voltage, Single

- Phase Design Lines

........................... 5

- 9 Table 5.2.6 Dry

- Type, Medium

- Voltage, Three

- Phase Design Lines

.......................... 5

- 10 Table 5.2.7 Common Scaling Relationships in Transformers

................................ ...... 5

- 11 Table 5.3.1 A and B Grid Combinations Used by Software to Generate Design Database

................................ ................................ ................................ ................................ ........ 5

- 15 Table 5.3.2 A and B Fan Combinations Used by Software to Generate Design Database

................................ ................................ ................................ ................................ ........ 5

- 15 Table 5.3.3 Core Steel Grades, Thicknesses and Associated Losses

............................ 5

- 17 Table 5.3.4 Core Configurations Used in E ach Design Line

................................ ........ 5

- 18 Table 5.3.5 Design Adjustments for Simulated Symmetric Core Designs

................... 5

- 23 Table 5.3.6 Core Deactivation Technology Components, Cost and Weight

................ 5

- 25 Table 5.3.7 Design Option Combinations for the Representative Unit from Design Line 1

................................ ................................ ................................ ................................ ........ 5

- 26 Table 5.3.8 Design Option Combinations for the Representative Unit from Design Line 2

................................ ................................ ................................ ................................ ........ 5

- 27 Table 5.3.9 Design Option Combinations for the Representative Unit from Design Line 3

................................ ................................ ................................ ................................ ........ 5

- 28 Table 5.3.10 Design Option Combinations for the Representative Unit from Design Line 4

................................ ................................ ................................ ................................ ...... 5

- 29 Table 5.3.11 Design Option Combinations for the Representative Unit from Design Line 5

................................ ................................ ................................ ................................ ...... 5

- 30 Table 5.3.12 Design Option Combinations for the Representative Unit from Design Line 6

................................ ................................ ................................ ................................ ...... 5

- 31 Table 5.3.13 Design Option Combinations for the Representative Unit from Design Line 7

................................ ................................ ................................ ................................ ...... 5

- 32 Table 5.3.14 Design Option Combinations for the Representative Unit from Design Line 8

................................ ................................ ................................ ................................ ...... 5

- 33 Table 5.3.15 Design Option Combinations for the Representative Unit from Design Line 9

................................ ................................ ................................ ................................ ...... 5

- 34 Table 5.3.16 Design Option Combinations for the Rep resentative Unit from Design Line 10

................................ ................................ ................................ ................................ .... 5

- 35 Table 5.3.17 Design Option Combinations for the Representative Unit from Design Line 11

................................ ................................ ................................ ................................ .... 5

- 35 Table 5.3.18 Design Option Combinations for the Representative Unit from Design Line 12

................................ ................................ ................................ ................................ .... 5

- 365

- iii

Table 5.3.19 Design Option Combinations for the Representative Unit from Design Line 13A

................................ ................................ ................................ ................................ . 5

- 37 Table 5.4.1 Typical Manufacturer‘s Material Prices for Liquid

- Immersed Design Lines 5

- 44 Table 5.4.2 Marked

- up Material Prices for Liquid

- Immersed Units, Current Year (2010) Price Scenario

................................ ................................ ................................ ................ 5

- 46 Table 5.4.3 Summary Table of Fixed Material Costs for Liquid

- Immersed Units

....... 5

- 48 Table 5.4.4 Manufactu rer‘s Material Prices for Dry

- Type Design Lines

..................... 5

- 49 Table 5.4.5 Marked

- up Material Prices for Dry

- Type Units, Current Year (2010) Price Scenario

................................ ................................ ................................ .......................... 5

- 50 Table 5.4.6 Summary Table of Fixed Material Costs for Dry

- Type Units

................... 5

- 53 Table 5.4.7 Labor Markups for Liquid

- Immersed and Dry

- Type Manufacturers

........ 5

- 54 Table 5.4.8 Summary of Labor Times for Liquid

- Immersed Units

.............................. 5

- 57 Table 5.4.9 Summary of Labor Times for Dry

- Type Units

................................ .......... 5

- 59 Table 5.5.1 Summary of Baselines and Efficiency Levels for Distribution Transformer Representative Units

................................ ................................ ................................ ...... 5

- 61 Table 5.5.2 Summary of Incremental Manufacturer Selling Prices Over the Baseline for Distribution Transformer Representative Units

................................ ............................. 5

- 62 Table 5.7.1 Bill of Materials for Transformer from Design Line 1

.............................. 5

- 90 Table 5.7.2 Bill of Materials for Transformer from Design Line 7

.............................. 5

- 94 Table 5.7.3 Bill of Materials for Transformer from Design Line 12

............................ 5

- 99

LIST OF FIGURES
Figure 5.3.1 A and B Combination Software Inputs Used in the Engineering Analysis

.. 5

- 16 Figure 5.3.2 Graphic of Single

- Phase Core Configurations

................................ ......... 5

- 19 Figure 5.3.3 Graphic of Three

- phase Core Configurations

................................ .......... 5

- 19 Figure 5.3.4 Cruciform Core Cross

- Section

................................ ................................ . 5

- 20 Figure 5.3.5 Graphic of Symmetric Core Configuration

................................ .............. 5

- 21 Figure 5.4.1 Method of Cost Accounting for Distribution Transformers Rulemaking 5

- 40 Figure 5.6.1 Engineering Analysis Results, Design Line 1

................................ .......... 5

- 64 Figure 5.6.2 Engineering Analysis Results, Design Line 2

................................ .......... 5

- 65 Figure 5.6.3 Engineering Analysis Results, Design Line 3

................................ .......... 5

- 66 Figure 5.6.4 Engineering Analysis Results, Design Line 4

................................ .......... 5

- 67 Figure 5.6.5 Engineering Analysis Results, Design Line 5

................................ .......... 5

- 68 Figure 5.6.6 Engineering Analysis Results, Design Line 6

................................ .......... 5

- 69 Figure 5.6.7 Engineering Analysis Results, Design Line 7

................................ .......... 5

- 70 Figure 5.6.8 Engineering Analysis Results, Design Line 8

................................ .......... 5

- 71 Figure 5.6.9 Engineering Analysis Results, Design Line 9

................................ .......... 5

- 72 Figure 5.6.10 Engineering Analysis Results, Design Line 10

................................ ...... 5

- 73 Figure 5.6.11 Engineering Analysis Results, Design Line 11

................................ ...... 5

- 74 Figure 5.6.12 Engineering Analysis Results, Design Line 12

................................ ...... 5

- 75 Figure 5.6.13 Engineering Analysis Results, Design Line 13A

................................ ... 5

- 76 Figure 5.6.14 Engineering Analysis Results, Design Line 13B

................................ ... 5

- 775

- iv

Figure 5.6.15 Symmetric Core Engineering Analysis Results, Design Line 4

............. 5

- 78 Figure 5.6.16 Symmetr ic Core Engineering Analysis Results, Design Line 5

............. 5

- 79 Figure 5.6.17 Symmetric Core Engineering Analysis Results, Design Line 7

............. 5

- 80 Figure 5.6.18 Symmetric Core Engineering Analysis Results, Design Line 8

............. 5

- 81 Figure 5.6.19 Symmetric Core Engineering Analysis Results, Design Line 9

............. 5

- 82 Figure 5.6.20 Symmetric Core Engineering Analysis Results, Design Line 10

........... 5

- 83 Figure 5 .6.21 Symmetric Core Engineering Analysis Results, Design Line 11

........... 5

- 84 Figure 5.6.22 Symmetric Core Engineering Analysis Results, Design Line 12

........... 5

- 85 Figure 5.6.23 Symmetric Core Engineering Analysis Results, Design Line 13B

........ 5

- 86 Figure 5.7.1 Manufacturer Selling Price Breakdown, Transformer from Design Line 1

. 5

- 91 Figure 5.7.2 Manufacturer Selling Price Breakdown, Transformer from Design Line 7

. 5

- 95 Figure 5.7.3 Manufacturer Selling Price Breakdown, Transformer from Design Line 12 5

- 1005

- 1 CHAPTER 5. ENGINEERING ANALYSIS

5.1 INTRODUCTION This chapter provides the technical support documentation on the engineering analysis, evaluating both liquid

- immersed and dry

- type distribution transformers

. The purpose of the engineering analysis is to estimate the relationship between the manufacturer‘s selling price of a transformer and its corresponding efficiency rating

. This relationship serves as the basis for the subsequent cost

- benefit c alculations for individual customer s , manufacturers, and the nation (see Chapter 8, Life

- Cycle Cost and Payback Period Analyses).

5.2 STRUCTURING THE ENGI NEERING ANALYSIS As discussed in the market and technology assessment (Chapter 3), distribution transforme rs are classified by their insulation type (liquid

- immersed or dry

- type), the number of phases (single or three), the primary voltage (low

- voltage or medium

- voltage for dry

- types) and the basic impulse insulation level (BIL) rating (for dry

- types)

. Followi ng this convention, the U.S. Department of Energy (DOE) developed ten equipment classes, shown in Table 5.2

. 1

. These equipment classes were adapted from the National Electrical Manufacturers Association (NEMA)‘s TP 1 classification system, although they do not follow the classification system precise ly

. NEMA‘s TP 1 classifies medium

- voltage, dry

- type distribution transformers into two equipment classes, ≤ 60 kilovolt (kV) BIL and > 60 kV BIL

. Based on input from manufacturers, DOE elected to increase the differentiation of medium

- voltage, dry

- type tra nsformers, and create three equipment classes of BIL ratings: 20

– 45 kV BIL, 46

– 95 kV BIL, and ≥ 96kV BIL (see Chapter 3, section 3.3).

Within each of these equipment classes, DOE further classified distribution transformers by their kilovolt

- ampere (kVA) rating

. These kVA ratings are size categories, indicating the power handling capacity of the transformers

. Due to differences in construction methods and material properties, efficiency levels vary by both equipment class and kVA rating

. For NEMA‘s TP 1

- 2 002, 1 there are 99 kVA ratings across all the equipment classes (see Chapter 3, section 3.7.1)

. For DOE‘s rulemaking, because of the greater degree of differentiation around the BIL rating in medium

- voltage, dry

- type transformers, there are 115 kVA ratings across all the equipment classes, as shown in Table 5.2

. 1

.

1 NEMA‘s TP 1

- 2002 can be found online at: http://www.nema.org/stds/tp1.cfm#download.5

- 2

Table 5.2

. 1 Equipment Classes and Number of kVA Ratings
Distribution Transformer Equipment Class kVA Range Number of kVA Ratings 1. Liquid

- immersed, medium

- voltage, single

- phase 10

– 833 13 2. Liquid

- immersed, medium

- voltage, three

- phase 15

– 2500 14 3. Dry

- type, low

- voltage, single

- phase 15

– 333 9 4. Dry

- type, low

- voltage, three

- phase 15

– 1000 11 5. Dry

- type, medium

- voltage, single

- phase, 20

- 45 kV BIL 15

– 833 12 6. Dry

- type, medium

- voltage, three

- phase, 20

- 45 kV BIL 15

– 2500 14 7. Dry

- type, medium

- voltage, single

- phase, 46

- 95 kV BIL 15

– 833 12 8. Dry

- type, medium

- voltage, three

- phase, 46

- 95 kV BIL 15

– 2500 14 9. Dry

- type, medium

- voltage, single

- phase, > 96 kV BIL 75

– 833 8 10. Dry

- type, medium

- voltage, three

- phase, > 96 kV BIL 225

– 2500 8 Total 115
DOE recognized that it would be impractical to conduct a detailed engineering analysis of the manufacturer‘s selling price

- efficiency relationship on all 115 kVA ratings, so it sought to develop an approach that simplified the analysis while retaining reas onable levels of accuracy

. DOE consulted with industry representatives and transformer design engineers and developed an understanding of the construction principles for distribution transformers

. It found that many of the units share similar designs and c onstruction methods

. Thus, DOE simplified the analysis by creating 1 4 engineering design lines, which group together kVA ratings based on similar principles of design and construction

. The 1 4 design lines subdivide the equipment classes, to improve the acc uracy of the engineering analysis. These 1 4 engineering design lines differentiate the transformers by insulation type (liquid

- immersed or dry

- type), number of phases (single or three), and primary insulation levels for medium

- voltage, dry

- type (three diff erent BIL levels).
DOE then selected one unit from each of the engineering design lines for study in the engineering analysis and the life

- cycle cost (LCC) analysis (see Chapter 8), reducing the number of units for analysis from 115 to 1 4

. It then extrapolated the results of its analysis from the unit studied to the other kVA ratings within that same engineering design line

. DOE performed this extrapolation in the national impacts analysis (see Chapter 10)

. The technique it used to extrapola te the findings on the representative unit to the other kVA ratings within a design line is referred to as ―the 0.75 scaling rule.‖ This rule states that, for similarly designed transformers, costs of construction and losses scale to the ratio of kVA rati ngs raised to the 0.75 power

. The relationship is valid where the optimum efficiency loading points of the two transformers being scaled are the same

. An example of how DOE applied this scaling appears in section 5.2.1 of this chapter

. A technical discussion on the derivation of the 0.75 scaling rule appears in Appendix 5B.

Table 5.2

. 2 presents DOE‘s 1 4 design lines and the representative units selected from each engineering design line for analysis

. Descriptions of each of the design lines and the rationale behind the sele ction of the representative units follow Table 5.2

. 2

.5

- 3

Table 5.2

. 2 Engineering Design Lines (DLs) and Representative Un its for Analysis
E C * DL Type of Distribution

Transformer kVA Range Representative Unit for this

Engineering Design Line

1 1 Liquid

- immersed, single

- phase,

rectangular tank 10

– 167 50 kVA, 65 C, single

- phase, 60Hz, 14400V primary, 240/120V secondary, rectangular tank
2 Liquid

- immersed, single

- phase, round tank 10

– 167 25 kVA, 65 C, single

- phase, 60Hz, 14400V primary, 120/240V secondary, round tank
3 Liquid

- immersed, single

- phase 250

– 833 500 kVA, 65 C, single

- phase, 60Hz, 14400V primary, 277V secondary

2 4 Liquid

- immersed, three

- phase 15

– 500 150 kVA, 65 C, three

- phase, 60Hz, 12470Y/7200V primary, 208Y/120V secondary
5 Liquid

- immersed, three

- phase 750

– 2500 1500 kVA, 65 C, three

- phase, 60Hz, 24940GrdY/14400V primary, 480Y /277V secondary
3 6 Dry

- type, low

- voltage, single

phase 15

– 333 25 kVA, 150 C, single

- phase, 60Hz, 480V primary, 120/240V secondary, 10kV BIL

4 7 Dry

- type, low

- voltage, three

phase 15

– 150 75 kVA, 150 C, three

- phase, 60Hz, 480V primary, 208Y/120V secondary, 10kV BIL
8 Dry

- type, low

- voltage, three

phase 225

– 1000 300 kVA, 150 C, three

- phase, 60Hz, 480V Delta primary, 208Y/120V secondary, 10kV BIL

6 9 Dry

- type, medium

- voltage,

three

- phase, 20

- 45kV BIL 15

– 500 300 kVA, 150 C, three

- phase, 60Hz, 4160V Delta primary, 480Y/277V secondary, 45kV BIL
10 Dry

- type, medium

- voltage, three

- phase, 20

- 45kV BIL 750

– 2500 1500 kVA, 150 C, three

- phase, 60Hz, 4160V primary, 480Y/277V secondary, 45kV BIL

8 11 Dry

- type, medium

- voltage,

three

- phase, 46

- 95kV BIL 15

– 500 300 kVA, 150 C, three

- phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL
12 Dry

- type, medium

- voltage, three

- phase, 46

- 95kV BIL 750

– 2500 1500 kVA, 150 C, three

- phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL

10 13 (A & B) Dry

- type, medium

- voltage, three

- phase, 96

- 150kV BIL 225

– 2500 300 kVA, 150 C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL 2000 kVA, 150 C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL * EC means equipment class (see Chapter 3 of the TSD)

. DOE did not select any representative units from the single

- phase, medium

- voltage equipment classes ( E C5 , E C7 and E C9 ) , but calculated the analytical results for E C5 , E C7 , and E C9 based on the results for their three

- phase counterparts. DOE divided liquid

- immersed transformers into five engineering design lines, based on their tank shape, number of phases, and kVA ratings

. DOE believes that this breakdown enables the analysis to identify and capture a more accurate representation of the m anufacturer‘s selling price and efficiency relationship

. DOE broke dry

- type distribution transformers into eight engineering design lines, primarily according to their BIL levels

. DOE believes this level of disaggregation is necessary to capture important differences in the price

- efficiency relationship, particularly as the BIL level varies

. For example, a 300 kVA, three

- phase, dry

- type unit could be classified in design lines 8, 9, or 11, or 13 A , depending on whether the BIL rating is 10 kV (low

voltage), 20

- 45 kV, 46

- 95 kV, or 96

- 150 kV.
For design lines 9 through 13 B , the representative units selected for some of the dry

- type design lines may not be the standard BIL s associated with a given primary voltage

. DOE selected a slightly higher BIL for the repr esentative units from these design lines to ensure that any minimum efficiency standard would not excessively penalize customers purchasing transformers5

- 4

at higher BIL ratings within the range

. For example, a 300 kVA transformer with a 4160V primary is call ed a ―5kV class‖ transformer and would normally be built with a 30kV BIL

. However, customers may also choose to order this transformer with 45kV BIL or 60kV BIL

. If the minimum efficiency level were set based on a 30kV BIL, it may not be possible to achiev e that same efficiency rating for customers ordering 60kV BIL

. Thus, DOE evaluated the middle BIL level (in this example, 45kV BIL), making it slightly easier to comply for a lower BIL, and not too difficult (or impossible) for the higher BIL.

The remain der of this section discusses each of the 1 4 engineering design lines, providing a description and explanation of the transformers covered.
Design Line 1

. This is the basic, high

- volume line for rectangular

- tank, single

- phase, liquid

- immersed distribution transformers, ranging from 10 kVA to 167 kVA

. Transformers in this design line typically have BIL s ranging from 30 kV to 150 kV and a tap configuration of four 21⁄2 percent taps

— two above and two below the nominal voltage

. Tap configurations enable transformer users to maintain full (rated) output voltage by slightly increasing or decreasing the number of turns in the primary in anticipation of an input voltage slightly above or below the rated nominal

. This design line has a primary voltage less tha n 35 kV, and a secondary voltage less than or equal to 600 Volts (V).
The representative unit selected for design line 1 is a 50 kVA pad

- mounted unit, as this is a high shipment volume rating, and is approximately the middle of the kVA range for this desi gn line (10 kVA, 15 kVA, 25 kVA, 37.5 kVA, 50 kVA, 75 kVA, 100 kVA, and 167 kVA)

. Engineering design considerations and manufacturing differences led to the placement of 250 kVA and higher

- rated units in design line 3.
Design Line 2

. This is the basic, high

- volume line for round

- tank (pole

- mounted), single

phase, liquid

- immersed distribution transformers, ranging from 10 kVA to 167 kVA. Although some manufacturers tend to employ the same basic core/coil design for design line 1 and des ign line 2, others may have design differences between pad

- mounted and pole

- mounted transformers

. DOE decided to analyze these two types of distribution transformers separately for the engineering and LCC analyses

. Transformers in design line 2 typically h ave BIL s ranging from 30 kV to 150 kV, a tap configuration of four 21⁄2 percent taps

— two above and two below the nominal, a primary voltage less than 35 kV, and a secondary voltage less than or equal to 600 V

. The representative unit selected for design li ne 2 is a 25 kVA pole

- mounted unit, as this is a high

- volume rating for pole

- mounted transformers, and is on the lower end of the kVA range for this design line (10 kVA, 15 kVA, 25 kVA, 37.5 kVA, 50 kVA, 75 kVA, 100 kVA, and 167 kVA)

. Engineering design c onsiderations and manufacturing differences led to the placement of 250 kVA and higher

- rated units in design line 3.
Design Line 3

. This design line groups together single

- phase, round

- tank, liquid

immersed distribution transformers, ranging from 250 kVA to 833 kVA

. Together, design lines 1 through 3 cover all the single

- phase, liquid

- immersed units (there are no standard kVA ratings between 167 and 250 kVA)

. Transformers in this design line typically have BIL s ranging from5

- 5

30 kV to 150 kV, a tap configura tion of four 21⁄2 percent taps

— two above and two below the nominal, a primary voltage less than 35 kV, and a secondary voltage less than or equal to 600 V.
The representative unit selected for design line 3 is a 500 kVA round

- tank, as this rating occurs in the middle of the kVA range for this design line (250 kVA, 333 kVA, 500 kVA, 667 kVA, and 833 kVA)

. Although high currents result from having a 277 V secondary at the larger kVA ratings, high current bushings are available, and a market does exist for thes e transformers.
Design Line 4

. Design line 4 represents rectangular tank, three

- phase, liquid

- immersed distribution transformers, ranging from 15 kVA to 500 kVA

. Transformers in this design line typically have BIL s ranging from 30 kV to 150 kV, a tap con figuration of four 21⁄2 percent taps

— two above and two below the nominal, a primary voltage less than 35 kV, and a secondary voltage less than or equal to 600 V.
The representative unit selected for design line 4 is a 150 kVA transformer, as this is a
commo n rating in this design line and occurs approximately in the middle of the kVA range (15 kVA, 30 kVA, 45 kVA, 75 kVA, 112.5 kVA, 150 kVA, 225 kVA, 300 kVA, and 500 kVA).
Design Line 5

. Design line 5 represents rectangular tank, three

- phase, liquid

- immers ed distribution transformers, ranging from 750 kVA to 2500 kVA

. Together, design lines 4 and 5 cover all the three

- phase, liquid

- immersed units (there are no standard kVA ratings between 500 and 750 kVA)

. Transformers in this design line typically have BIL s ranging from 95 kV to 150 kV, a tap configuration of four 21⁄2 percent taps

— two above and two below the nominal, a primary voltage less than 35 kV, and a secondary voltage less than or equal to 600 V.
The representative unit selected for this design line is a 1500 kVA transformer, as this is a common rating in this size range, and occurs in the middle of the kVA range for this design line (750 kVA, 1000 kVA, 1500 kVA, 2000 kVA, and 2500 kVA).
Design Line 6

. Design line 6 represents single

- phase, low

- voltage, ventilated dry

- type distribution transformers, ranging from 15 kVA to 333 kVA

. Transformers in this design line typically have BIL ratings of 10 kV and a ―universal‖ tap arrangement, meaning six 21⁄2 percent taps, two above and fou r below the nominal

. DOE selected this tap arrangement based on recommendations from manufacturers who produce transformers at these ratings

. The primary and secondary voltages are both 600 V or below.
The representative unit selected for design line 6 is a 25 kVA transformer, as this is a common rating in this size range, and occurs toward the low end of the kVA ratings for this design line (15 kVA, 25 kVA, 37.5 kVA, 50 kVA, 75 kVA, 100 kVA, 167 kVA, 250 kVA, and 333 kVA).
Design Line 7

. Design line 7 re presents three

- phase, low

- voltage, ventilated dry

- type distribution transformers, ranging from 15 kVA to 150 kVA

. Because the kVA range of three

phase ratings is broad and construction techniques differ, DOE split the range of three

- phase, low

- voltage, dry

- type transformers into design line 7 and design line 8, so the engineering differences in core

- coil design and manufacturing would be more readily apparent

. Transformers5

- 6

in this design line typically have BIL ratings of 10 kV and a ―universal‖ tap arrange ment, meaning six 21⁄2 percent taps, two above and four below the nominal

. The primary and secondary voltages are both 600 V or below.
The representative unit selected for design line 7 is a 75 kVA transformer, as this is a common rating in this size range, and occurs in the middle of the kVA ratings for this design line (15 kVA, 30 kVA, 45 kVA, 75 kVA, 112.5 kVA, and 150 kVA).
Design Line 8

. Design line 8 represents three

- phase, low

- voltage, ventilated dry

- type distribution transformers, ran ging from 225 kVA to 1000 kVA

. Transformers in this design line typically have BIL ratings of 10 kV and a tap arrangement of four 21⁄2 percent taps, two above and two below the nominal

. The primary and secondary voltages are both 600 V or below.
The representative unit selected for design line 8 is a 300 kVA transformer, as this is a common rating in this size range, and occurs toward the lower end of the range of kVA ratings included in this design line ( 225 kVA, 300 kVA, 500 kVA, 750 kVA, and 1000 kVA ).
Design Line 9

. Design line 9 represents three

- phase, medium

- voltage, ventilated dry

- type distribution transformers, ranging from 15 kVA to 500 kVA

. To accommodate the broad kVA range and to allow for engineering differences in construction principles and associated costs, DOE split the three

- phase, medium

- voltage, dry

- type units into design lines 9 and 10

. Transformers in design line 9 typically have primary voltages less than o r equal to 5 kV with a BIL rating between 20 kV and 45 kV

. The secondary voltage is less than or equal to 600 V and the tap arrangement is typically four 21⁄2 percent taps, two above and two below the nominal.
The representative unit selected for design li ne 9 is 300 kVA, as this is a common rating in this size range, and occurs near the high end of the kVA ratings for this design line (15 kVA, 30 kVA, 45 kVA, 75 kVA, 112.5 kVA, 150 kVA, 225 kVA, 300 kVA, and 500 kVA).
Design Line 10

. Design line 10 repres ents three

- phase, medium

- voltage, ventilated dry

type distribution transformers, ranging from 750 kVA to 2500 kVA

. Transformers in this design line typically have primary voltages less than or equal to 5 kV with a BIL rating between 20 kV and 45 kV

. The se condary voltage is less than or equal to 600 V and the tap arrangement is typically four 21⁄2 percent taps, two above and two below the nominal.
The representative unit selected for this design line is a 1500 kVA transformer, as this is a common rating, and occurs in the middle of the kVA range for this design line (750 kVA, 1000 kVA, 1500 kVA, 2000 kVA, and 2500 kVA)

. Design Line 11

. Design line 11 represents three

- phase, medium

- voltage, ventilated dry

type distribution transformers, ranging from 15 kVA to 500 kVA

. This design line parallels design line 9, with a higher primary insulation level, 46 kV to 95 kV BIL

. Because dry

- type transformer designs and, more importantly, the efficiency of those designs, are strongly influenced by changes in BIL, DOE co nsidered these higher BIL ratings separately

. The typical tap arrangement is four 21⁄2 percent taps, two above and two below the nominal

. The primary5

- 7

voltage is typically less than or equal to 15 kV and the secondary voltage is less than or equal to 600 V

. The kVA ratings in design line 11 are 15 kVA, 30 kVA, 45 kVA, 75 kVA, 112.5 kVA, 150 kVA, 225 kVA, 300 kVA, and 500 kVA

. The shipments for this design line are primarily in the kVA range inclusive of and between 225 kVA and 500 kVA; therefore, DOE selecte d the 300 kVA rating as the representative unit for analysis.
Design Line 12

. Design line 12 represents three

- phase, medium

- voltage, ventilated dry

type distribution transformers, ranging from 750 kVA to 2500 kVA

. This design line parallels design line 10 , with a higher primary insulation level, 46 kV to 95 kV BIL

. The typical tap arrangement is four 21⁄2 percent taps, two above and two below the nominal

. The primary voltage is typically less than or equal to 15 kV and the secondary voltage is less than or e qual to 600 V.
The representative unit selected for this design line is a 1500 kVA transformer, as it is a common rating in this size range and BIL rating, and it occurs in the middle of the kVA range covered by this design line (750 kVA, 1000 kVA, 1500 kVA, 2000 kVA, and 2500 kVA)

. Design Line s 13

A and 13B

. As a further extension on the dry

- type, three

- phase, medium

voltage BIL ranges, DOE originally analyzed 96 kV to 150 kV BIL in a single design line ranging from 225 kVA to 2500 kVA

. The 225 kVA rati ng is considered to be the lowest kVA rating where one would expect to see a unit with a BIL greater than 110 kV

. The typical tap arrangement is four 21⁄2 percent taps, two above and two below the nominal

. The primary voltage is typically less than or equal to 35 kV and the secondary voltage is less than or equal to 600 V.
This third set of dry

- type, three

- phase, medium

- voltage distribution transformers spans a wide range of kVA ratings

. (225 kVA, 300 kVA, 500 kVA, 750 kVA, 1000 kVA, 1500 kVA, 2000 kVA, and 2500 kVA). Based on comments received after the preliminary analysis, DOE decided to split the former design line 13 into two design lines , 13A and 13B, in order to improve scaling accuracy within EC10

. T he representative unit selected for design line 13 A is a 300 kVA transformer

. This unit is a common rating in this size range, and occurs toward the low end of the range covered by this design line

. The representative unit selected for design line 13 B is a 2000 kVA transformer, which occurs toward the hig h end of the range covered by this design line.

In addition to the three equipment classes for dry

- type, medium

- voltage, three

- phase distribution transformers (for which there are five engineering design lines) presented in Table 5.2

. 1 , there are three equipment classes for single

- phase, dry

- type, medium

- voltage units

. As discussed in Chapter 3, the shipment volume for single

- phase, dry

- type, medium

- voltage transfor mers is very low as a percentage of the total dry

- type shipments

. Additionally, the total megavolt

- ampere ( MVA ) capacity of single

- phase, dry

- type, medium voltage transformers is relatively low as a percentage of the total MVA capacity for dry

- type, medium voltage transformers

. Therefore , it does not warrant the level of effort involved in conducting analysis on these specific units

. DOE decided instead to scale the analysis findings from three

- phase units to the single

- phase units by establishing the same energy conservation standard requirement on a5

- 8

 ̳per phase‘ basis

. In other words, DOE would scale the energy conservation standard requirements for a three

- phase 1500 kVA medium

- voltage dry

- type to be the same for a single

phase 500 kVA medium

- voltage dry

- type unit

. In this way, DOE was able to concentrate resources and improve the accuracy in other, higher volume and more important distribution transformer equipment classes

. DOE used the same approach in the previous rulemaking for dist ribution transformers.

5.2.1 Summary of Design Line Coverage The following four tables summarize the coverage of each of the design lines in relation to the various equipment classes and kVA ratings

. The abbreviation DL stands for design line, and the row in th e table where the phrase ―Rep Unit‖ appears indicates the kVA rating of the representative unit from that design line

. The representative unit is the kVA rating that DOE analyzed in the engineering and LCC analyses

. For example, DL1 stands for design line 1, spanning from 10 to 167 kVA liquid

- type, single

- phase

. The label ―Rep Unit‖ appears in row 50 kVA, indicating that the 50 kVA is the representative unit for DL1

. Similarly, the representative unit for DL2 is the 25 kVA unit

. There are five liquid

- imme rsed transformer design lines, three single

- phase and two three

phase, as shown in Table 5.2

. 3

. To capture any design differences between a single

- phase pole and a pa d

- mounted transformer, DOE analyzed units in both DL1 and DL2, spanning the same kVA ratings (10 kVA to 167 kVA)

. On the three

- phase liquid

- immersed side, there is no overlap between those two design lines.

Table 5.2

. 3 Liquid

- Immersed Design Lines and Representative Units

Table 5.2

. 4 presents the low

- voltage, dry

- type design lines

. For single

- phase units, one design line spans all nine kVA ratings

. For the three

- phase units, two design lines cover the 115

- 9

kVA ratings in th at equipment class

. There is no overlap in the design lines for low

- voltage dry

type transformers.

Table 5.2

. 4 Dry

- Type, Low

- Voltage Design Lines and Representative Units

Table 5.2

. 5 presents equipment classes (abbreviated ― EC ‖ in this table) for medium

voltage, single

- phase, dry

- type units

. As discussed in Chapter 3, section 3.4 (National Shipment Estimate), these un its have a low shipment volume and low total MVA capacity

. All three equipment classes shown in Table 5.2

. 5 together represent less than one

- quarter of one percent of dry

- type shipments on an MVA capacity basis , and less than one percent of medium

- voltage dry

type shipments on an MVA capacity basis

. Thus, DOE did not consider it appropriate to conduct analys e s of any units from these three equipment classes.
As an alternative to investing time and resources analyzing these low

- volume units, DOE used the results from the medium

- voltage, three

- phase, dry

- type units (presented in Table 5.2

. 6 ) and divided those findings by three, creating virtual (calculated) representative units (labeled as ―Virtual RU‖ in Table 5.2

. 5 ) for these three equipment classes

. DOE used the representative units from design lines 9, 10, 11, 12, 13 A, and 13B

. These virtual representative units are shown i n their respective rows, following the application of the quotient

. For example, in the single phase (20

- 45kV BIL) column, the representative unit from DL9 is a three

- phase 300 kVA unit (see Table 5.2

. 6 ), so it scales to a single

- phase, 100 kVA unit in Table 5.2

. 5

. Table 5.2

. 5 Dry

- Type, Medium

- Voltage, Single

- Phase Design Lines5

- 10

Table 5.2

. 6 presents the equipment classes (abbreviated ― EC ‖ in this table) for the medium

- voltage, three

- phase, dry

- type distribution transformers and each of the design lines and respective representat ive units

. Because those equipment classes have high volume s and large range s of kVA ratings, DOE used two separate design lines for each, to maintain accuracy

. Within DL13 A , DOE did not extrapolate the results of this unit to ratings of 150kVA and below b ecause there were no shipments at these ratings in the shipments analysis and it is very unlikely that they would be built.

Table 5.2

. 6 Dry

- Type, Medium

- Voltage, Three

- Phase Design Lines

5.2.2 Scaling Relationsh ips in Transformer Manufacturing DOE simplified the engineering analysis by creating design lines, selecting representative units from these design lines, and scaling the results of the analysis on these representative units within their respective design lines

. This section briefly introduces the scaling relationship DOE used to extrapolate the findings on the representative units to the other kVA ratings

. A more detailed discussion of the derivation of the 0.75 scaling rule is provided in Appendix 5B.5

- 11

The scaling formulae are mathematical relationships that exist between the kVA ratings and the physical size, cost, and performance of transformers

. The size

- versus

- performance relationships arise from fundamental equations describing a transformer's volta ge and kVA rating

. For example, when the kVA rating, voltage, and frequency are fixed, the product of the conductor current density, core flux density, core cross

- sectional area, and total conductor cross

sectional area is constant.
To illustrate this p oint, consider a transformer with four fixed variables: frequency, magnetic flux density, current density, and BIL rating

. If one enlarges (or decreases) the kVA rating, then the only parameters free to vary are the core cross

- section and the core window area through which the windings pass

. Thus, to increase (or decrease) the kVA rating, the dimensions for height, width, and depth of the core/coil assembly scale equally in all directions

. Analysis of this scaling relationship reveals that each of the line ar dimensions varies as the ratio of kVA ratings to the 1⁄4 power

. Similarly, areas vary as the ratios of kVA ratings to the 1⁄2 power and volumes vary as the ratio of the kVA ratings to the 3⁄4 or 0.75 power, hence the term "0.75 scaling rule." Application of the 0.75 scaling rule assumes that the efficiency profile of a given transformer will have the same shape as the transformer being scaled

. Table 5.2

. 7 depicts the
mos t common scaling relationships in transformers.

Table 5.2

. 7 Common Scaling Relationships in Transformers

Parameter Being Scaled Relationship to kVA Rating (varies with ratio of kVA x ) Weight (kVA 1 /kVA 0 ) 3/4
Cost (kVA 1 /kVA 0 ) 3/4 Length (kVA 1 /kVA 0 ) 1/4
Width (kVA 1 /kVA 0 ) 1/4 Height (kVA 1 /kVA 0 ) 1/4
Total Losses (kVA 1 /kVA 0 ) 3/4
No

- load Losses (kVA 1 /kVA 0 ) 3/4

The following three relationships are true as the kVA rating increases or decreases, if the type of transformer (liquid

- immersed or dry

- type, single

- phase or three

- phase), the primary voltage, the core configuration, the core material, the core flux density, and the current density (amperes per square inch o f conductor cross

- section) in both the primary and secondary windings are all held constant:

1. The physical proportions are constant (same relative shape), 2. The eddy loss proportion is essentially constant, and 3. The insulation space factor (voltage or BIL) is constant. In practical applications, it is rare to find that all of the above are constant over even limited ranges; however, over a range of one order of magnitude in both directions (e.g., from 50 kVA to 5 kVA or from 50 kVA to 500 kVA), the scaling ru les shown in Table 5.2

. 7 can be used5

- 12

to establish reasonable estimates of performance, dimensions, costs, and losses

. In practice, these rules can be applied over even wider ranges to estimate general performance levels

. To illustrate how DOE used the scaling laws, consider two transformers with kVA ratings of S 0 and S 1 . The no

- load losses (NL) and total losses (TL) of these two transformers would be depicted as NL 0 and TL 0 , and NL 1 and TL 1 . Then the relationships between the NL and TL of the two transformers could be shown as follows:

Equation 5.2

. 1 NL 1 = NL 0 (S 1 / S 0 ) 0.75

where:

NL 1 = no

- load losses of transformer ―1,‖ NL 0 = no

- load losses of transformer ―0,‖ S 1 = kVA rating of transformer ―1,‖ and S 0 = kVA rating of transformer ―0.‖

and Equation 5.2

. 2 TL 1 = TL 0 (S 1 / S 0 ) 0.75

where:

TL 1 = total losses of transformer ―1,‖ and TL 0 = total losses of transformer ―0.‖
Equation 5.2

. 1 and Equation 5.2

. 2 can be manipulated algebraically to show that the load loss also varies to the 0.75 power

. Starting with the concept that total losses equal no

- load losses plus load losses, DOE can derive the relationship for load loss (LL), and show that it also scales to the 0.75 power

. Specifically:

Equation 5.2

. 3 LL 1 = TL 1 - NL 1
where:

LL 1 = load losses of transformer ―1‖

Inserting the TL 1 and NL 1 terms into this equation, DOE finds:5

- 13 Equation 5.2

. 4 LL 1 = (TL 0 (S 1 / S 0 ) 0.75 )

- (NL 0 (S 1 / S 0 ) 0.75 ) Equation 5.2

. 5 LL 1 = (TL 0 - NL 0 ) (S 1 / S 0 ) 0.75 Equation 5.2

. 6 LL 1 = (LL 0 ) (S 1 / S 0 ) 0.75

where:

LL 0 = load losses of transformer ―0.‖
Thus, the 0.75 scaling rule can be applied to estimate the losses of a transformer, given the losses and kVA rating of a reference (analyzed) unit

. However, in order for this rule to be applicable, the transformer type must be the same, a nd key parameters

— such as the type of core material, core flux density, and conductor current density in the high and low voltage windings

— must be fixed

. Additionally, use of the 0.75 scaling rule assumes that the efficiency profile of a given transformer will have the same shape as the transformer being scaled

. See Appendix 5B for detailed discussion on the derivation of the 0.75 scaling rule

. DOE used the 0.75 scaling rule to scale the analysis findings on each of the representative units within the 1 4 design lines to the 102 kVA ratings that it did not analyze

. DOE applied the scaling rule within the design lines in the national impact analysis (Chapter 10), where it calculated efficiency ratings for the 102 kVA ratings not analyzed.

5.3 TECHNICAL DESIGN INPUTS

For all 1 4 representative units, the engineering analysis explored the relationship between the manufacturer selling prices and corresponding transformer efficiencies

. For this analysis, DOE contracted Optimized Program Service, Inc. (OPS) in Ohio, a software company specializing in transformer design since 1969

. Using a range of input parameters and material prices, the OPS software produces a design

. This design has specific information about the core and coil, including physical characteristics, d imensions, material requirements, and mechanical clearances, as well as a complete electrical analysis of the final design

. This optimized, practical transformer design, the bill of materials, and an electrical analysis report contain sufficient informatio n for a manufacturer to build the unit

. DOE uses the software‘s output to generate an estimated cost of manufacturing materials and labor, which it then converts to a manufacturer selling price by applying markups.
The electrical analysis report estimates the performance of the transformer design (including efficiency) at 25 percent, 35 percent, 50 percent, 65 percent, 75 percent, 100 percent, 125 percent, and 150 percent of nameplate load

. The software output provides a clear understanding of the relation ship between cost and efficiency because it provides detailed data on design variances, as well as a bill of materials, labor costs, and efficiency

. The software does not capture retooling costs associated with changing production designs for a specific5

- 14

ma nufacturer

. In some cases, however, DOE captured tooling costs associated with manufacturing mitered cores by applying adders to the steel price.

5.3.1 A and B Loss Valuation Inputs One of the inputs to the design software consisted of a range of what are know n in the industry as A and B evaluation combinations (see Chapter 3, section 3.6, Total Ownership Cost Evaluation)

. The combination of A and B input to the design software mimics a distribution transformer purchase order

. The A parameter represents a custo mer's present value of future losses in the transformer core (no

- load losses)

. The B value represents a customer's present value of future losses in the windings (load losses)

. The B parameter is never larger than A, as this would imply a specification for a transformer whose average load would be more than 100 percent of the nameplate load

. The A and B values take into account a range of factors that usually vary from customer to customer.
The A and B values are expressed in terms of dollars per watt of loss

. The greater the values of A and B, the greater the importance a customer attaches to the value of future transformer losses

. As A and B values increase, the customer places greater importance on reducing the watts of core and winding losses, respect ively, and so the customer chooses a more energy

- efficient transformer.
DOE used broad ranging combinations of A and B evaluation formulae (presented in Table 5.3

. 1 and Tabl e 5.3

. 2 ) to create a complete set of efficiency levels for each design option combination ana lyzed

. The efficiency levels spanned from a low

- first

- cost unit to a maximum technologically feasible (―max

- tech‖) design

. For the low

- first

- cost design, the A and B evaluation values were both $0/watt, indicating that the customer does not attach any fina ncial value to future losses in the core or coil of the transformer

. For the maximum technologically feasible design, the A and B evaluation values were very high, pushing the software to design at the highest efficiencies achievable.

DOE created its comb inations of A and B evaluation formulae combining two techniques to ensure there were sufficient designs in the database for the analysis

. The first technique was to create a  ̳grid‘ of A and B combinations

. The  ̳grid‘ technique involved increasing the valu e of A by a step value, and then increasing the B value from zero to that value of A, using a different step value

. Thus, if A had incremental steps of $0.25 and B had steps of $0.20, the combinations would work as follows: ($0.00, $0.00), ($0.25, $0.00), ($0.25, $0.20), ($0.50, $0.00), ($0.50, $0.20), ($0.50, $0.40), ($0.75, $0.00), and so on

. Table 5.3

. 1 presents the ranges and incremental steps for the A and B combi nations used in the three grids.5

- 15

Table 5.3

. 1 A and B Grid Combinations Used by Software to Generate Design Database Grid Number A values

and increments B values and increments Resultant # of (A, B) combinations 1 $0 to $2 by 0.25 steps $0 to $2 by 0.20 steps 47 2 $2.50 to $8 by 0.50 steps $0 to $8 by 0.40 steps 157 3 $9 to $16 by 1.00 steps $3 to $8 by 0.50 steps 85
The second technique for generating A and B evaluation formulae in the engineering analysis is called the ―fan.‖ DOE understands that the ratio of A to B represents an implicit loading for the transformer

. Therefore, DOE created a set of (A, B) values in w hich the B is calculated from the A

. The B term is calculated as the A times the percent load squared

. In other words, if A equals $1 and DOE is interested in calculating the appropriate B for a 50 percent root

- mean

- square (RMS) load, then it would be $1 t imes (0.50)^2, or $0.25

. Thus, the combination of ($1.00, $0.25) represents approximately a 50 percent RMS load

. As with the ―grid,‖ the A values increased with a step function, and B values were calculated as fractions of A so that the ratio of A to B enc ompassed the RMS loading points that were identified in DOE‘s loading analysis (i.e., 35 percent and 50 percent)

. DOE calculated the B values for each A at the following RMS loading points: 5 percent, 10 percent, 15 percent, 20 percent, 25 percent, 30 perc ent, 35 percent, 40 percent, 45 percent, 50 percent, 55 percent, and 60 percent

. Tabl e 5.3

. 2 presents the range of the two fan combinations used in the analysis

. Tabl e 5.3

. 2 A and B Fan Combinations Used by Software to Generate Design Database
Fan Number A values

and increments B values and increments Resultant # of (A,B) combinations 1 $0 to $2 by 0.50 steps 5% to 60% implicit loading by 5% steps 47 2 $3 to $16 by 1.00 steps 5% to 60% implicit loading by 5% steps 182
When used together, these two techniques created a broad spectrum of A and B combinations as inputs to the OPS software

. Figure 5.3

. 1 illustrates the coverage of designs for the 518 A and B combinations

. DOE used each of these A and B pairs with each combination of core steel and winding material analyzed for each representative transformer design line studied.5

- 16

Figure 5.3

. 1 A and B Combination Software Inputs Used in the Engineering Analysis
Occasionally, the design software generated the same transformer design f or two different A and B combinations, creating duplicate designs in the engineering analysis database

. DOE removed these duplicate designs before the engineering database was imported into the LCC analysis

. Similarly, DOE removed any designs that yielded an efficiency value below the current standard level efficiency.

5.3.2 Core Material Options DOE understands that there are many ways to build a transformer, even with constant kVA and voltage ratings

. For instance, manufacturers can vary the core steels (e.g. , M2, M3, M6), the winding materials (aluminum or copper), and core configurations (shell or core

- type)

. For each of the design lines, DOE provides tables listing the design option combinations that it used to analyze each of the representative units

. Depe nding on customer needs, the cost of materials, the capital equipment in their facility, and the skills of their labor force, manufacturers make decisions on how to manufacture a given transformer using different core configurations, core steels, and windi ng materials

. To capture this variation in designs, DOE analyzed the 1 4 representative units using 5

– 8 different design option combinations of core type, core steel, and winding material

. As discussed in the technology assessment (see Chapter 3), core st eel is produced in a range of qualities (from an efficiency perspective)

. M2 core steel is oriented grain silicon steel and has thin laminations, and consequently has very low losses

. M 12 core steel is5

- 17

non

- oriented grain sil icon steel and is rolled in thic ker laminations, thus contributing to higher core losses

. Table 5.3

. 3 lists all the steel types used in the analysis, and properties associated with these steels

. Each steel grade provides the nominal thickness and core losses per pound of steel, under a specified typical magnetic flux density, measured in Tesla (T).

Table 5.3

. 3 Core Steel Grades, Thicknesses and Associated Losses
Steel Grade Nominal

Thickness inches Core Loss at 60 Hz

Watts per Pound at magnetic flux density * Notes / Remarks

M 12 0.014 1.36 Watts/lb at 1.5 T Non

- oriented grain silicon steel
M6 0.014 0.60 Watts/lb at 1.5 T 0.84 Watts/lb at 1.7 T Grain

- oriented silicon steel

M5 0.012 0.51 Watts/lb at 1.5 T 0.74 Watts/lb at 1.7 T Grain

- oriented silicon steel

M4 0.011 0.46 Watts/lb at 1.5 T 0.66 Watts/lb at 1.7 T Grain

- oriented silicon steel

M3 0.009 0.39 Watts/lb at 1.5 T 0.60 Watts/lb at 1.7 T Grain

- oriented silicon steel

M3 Lite Carlite 0.009 0.39 Watts/lb at 1.5 T 0.59 Watts/lb at 1.7 T Grain

- oriented silicon steel with insulative coating

M2 0.007 0.38 Watts/lb at 1.5 T 0.58 Watts/lb at 1.7 T Grain

- oriented silicon steel

M2 Lite Carlite 0.007 0.37 Watts/lb at 1.5 T 0.57 Watts/lb at 1.7 T Grain

- oriented silicon steel with insulative coating

H

- 0 DR 0.009 0.34 Watts/lb at 1.5 T 0.47 Watts/lb at 1.7 T Domain

- refined, high permeability grade silicon steel

ZDMH 0.009 0.38 Watts/lb at 1.5 T 0.57 Watts/lb at 1.7 T Imported silicon steel, magnetic domain

- refined by mechanical process

SA1 0.001 0.108 Watts/lb at 1.3 5 T 0.098 Watts/lb at 1.3 T Amorphous core steel (silicon and boron); flux density limitation

- testing at ~ 1.3 T * Watts of loss per pound of core steel are only comparable at the same magnetic flux density (measured in Tesla).

5.3.3 Core Configurations In addition to selecting a core steel, the manufacturer‘s selection of a core design may also contribute to the overall efficiency of a transformer

. A transformer facility may be optimized to work around one or two core configurations

. Table 5.3

. 4 provides a list of all the core configurations used for each of the 1 4 design lines

. DOE selected these configurations, in combination with the range of core steels and winding materials, to represent the most common construction methods for these kVA ratings in the U.S. market.5

- 18

Table 5.3

. 4 Core Configurations Used in Each Design Line Design Line # Phases Core Configurations Used in the Engineering Analysis

D L1 1 Wound core

- distribute d gap; S hell

- type

DL2 1 Wound core

- distributed gap; S hell

- type or core

- type

DL3 1 Wound core

- distributed gap; S hell

- typ e or core

- type

DL4 3 Wound core

- distributed gap or symmetric core; 5

- leg

DL5 3 Wound core

- distributed gap or symmetric core; 5

- leg

DL6 1 Wound core

– distributed gap; or s tacked , butt

- lap or step

- lap mitered ; S hell

- type or core

- type

DL7 3 Wound core

- distributed gap or symmetric core ; or s tacked butt

- lap , step

- lap or full mitered ; 3

- leg or 5

- leg

DL8 3 Wound core

- distributed gap or symmetric core ; or stacked butt

- lap , step

- lap or full mitered; 3

- leg or 5

- leg

DL9 3 Wound core

- distributed gap or symmetric core ; or stacked full mitered ; 3

- leg or 5

- leg

DL10 3 Wound core

– distributed gap or symmetric core ; or s t acked, cruciform, mitered joint; 3

- leg

DL11 3 Wound core

– distributed gap or symmetric core ; or s tacked , step

- lap or full mitered; 3

- leg or 5

- leg

DL12 3 Wound core

– distributed gap or symmetric core ; or s tacked, cruciform or step

- lap mitered joint ; 3

- leg or 5

- leg
DL13 (A & B) 3 Wound core

– distributed gap or symmetric core ; or s tacked, cruciform or step

- lap mitered joint ; 3

- leg or 5

- leg

5.3.3.1 Standard Core Configurations For the single

- phase representative units, the configurations used are either core

- type or shell

- type

. This applies whether the core consists of stacked or wound laminations of core steel

. For wound cores, manufacturers generally employ a technique known as  ̳distributed gap.‘ This means that each lamination of core steel wound around the form will have a start and finish point (the  ̳gap‘), staggered with respect to the previous and the next lamination

. Distributed gap core construction techniques are used to minimize the perfo rmance impact of the lamination joint gaps (reducing the exciting current) and, by locating inside the coil window, reduce the5

- 19

transformer‘s operating sound level

. Figure 5.3

. 2 illustrates the two types of single

- phase core construction.

Figure 5.3

. 2 Graphic of Single

- Phase Core Configurations

Three

- phase transformers can have three

- legg ed, four

- legged, five

- legged, Evans , or symmetric cores

. In the engineering analysis, DOE considered the three

- legged construction techniques for the three

- phase dry

- types and five

- legged construction for the three

- phase liquid

immersed transformers

. Some of t he dry

- type designs using an amorphous core also use a five

legged construction technique

. Figure 5.3

. 3 below illustrates the difference between the three

legged a nd the five

- legged core construction techniques

. A three

- legged core is assembled from stacked laminations, the joints of which can be butt

- lapped or mitered

. Where there is an economic need to reduce core losses, particularly in keeping with the use of mo re efficient grades of core steel (M2 or M3), the mitered core tends to be selected

. DOE recognizes that there are a variety of approaches to mitered core construction: ―scrapless T

- mitering,‖ ―full

- mitering,‖ and ―step

- mitering.‖ DOE modeled full

- mitere d and step

- mitered cores

.

Figure 5.3

. 3 Graphic of Three

- phase Core Configurations
For larger kVA ratings, design economics may cause the selection of a cruciform core section, where multiple lamination widths are stacked in increasing and then decreasing widths to create a circular core form (or ―log‖) around which the windings are placed

. Figure 5.3

. 4

SHELL TYPE CORE TYPE5

- 20

illustrates the cruciform core by showing a cross

- section

. This figure shows four different widths of steel being used, but there can be fewer or more widths, depe nding on the design

. By using a core configuration that better follows the contours of the windings, losses are again reduced, resulting in a more efficient transformer

. The use of the three

- legged core usually depends on the primary winding being delta

- co nnected

. If the primary winding is wye

- connected, as is frequently the case for pad

- mounted transformers used in underground distribution, the core configuration needs to be four

- legged or five

- legged.

Figure 5.3

. 4 Cruciform Core Cross

- Section

The five

- legged core is assembled from four wound

- core loops, and is the common configuration for liquid

- filled, three

- phase distribution transformers having a wye

- wye voltage connection

. Again, this occurs for pad

- mounted transformers used in underground distribution

. The individual core loops have distributed gaps, as explained for single

- phase, wound

- core transformers.

5.3.3.2 Symmetric Core Configurations In a symmetric core configuration, each leg of a three

- phase transformer is identically connected to the other two

. It uses a continuously wound core with 120 ̊ radial symmetry, resulting in a triangularly shaped core when viewed from above

. In a traditional core, the center leg is magnetically distinguishable from t he other two because it has a shorter average flux path to each

. In a symmetric core, however, no leg is magnetically distinguishable from the other two

. Figure 5.3

. 5 shows the configuration of the symmetric core design. 2

2 Lundmark, Sonja. Computer Model of Electromagnetic Phenomena in Hexaformer

. 2007. Available at: http://www.hexaformer.com/ExternaDokument/chalmers_report1.pdf

.5

- 21 Figure 5.3

. 5 Graphic of Symmetric Core Configuration
The symmetric core constr uction offers several advantages over traditional transformer
cores

. These include lowered weight, volume, no

- load losses, noise, vibration, stray magnetic fields, inrush current, and power in the third harmonic

. Transformers using this core construction
c an oftentimes use fewer pounds of core steel than a standard core would use to achieve a given efficiency

. As a result, total material cost for symmetric core designs is typically lower than that of a standard transformer design

. However, the advanced manu facturing processes necessary to produce the core increases the cost of labor and overhead for this core configuration

. Similarly, the appropriate equipment requires large capital expenditures to manufacture this core type.

Because of zero

- sequence fluxes associated with wye

- wye connected transformers, symmetric core designs are best suited to delta

- delta or delta

- wye connections. While traditional cores can circumvent the problem of zero

- sequence fluxes by introducing a fourth or fifth unwound leg, core s ymmetry makes extra legs inherently impractical. Yet another way to mitigate zero

- sequence fluxes comes in the form of a tertiary winding, which is delta

- connected and has no external connections. This winding is dormant when the transformer‘s load is bala nced across its phases. Although symmetric core designs may, in theory, be made tolerant of
zero

- sequence fluxes by employing this method, it comes at extra cost and complexity.
Using this tertiary winding, DOE believes that symmetric core designs can se rvice nearly all distribution transformer applications in the United States

. Most dry

- type transformers have a delta connection and would not require a tertiary winding

. Similarly, most liquid

- immersed transformers serving the industrial sector have a delt a connection

. These market segments could use the symmetric core design without any modification for a tertiary winding

. However, in the5

- 22

United States , most utility

- operated distribution transformers are wye

- wye connected. These transformers would require the tertiary winding in a symmetric core design.
DOE was unable to identify a company with commercial modeling software that c ould model symmetric core designs, but DOE did sp eak with many transformer manufacturers and industry experts about symmetric core designs

. Through these conversations, DOE received information on a few symmetric core designs

. These designs were insufficient to conduct a full

scale engineering analysis compara ble to the other design types

. In the preliminary analysis , DOE was able to approximate the cost

- efficiency relationship for symmetric core designs based on trends in the data received from manufacturers, published literature, and through conversations with indus try experts

. For each three

- phase design line, DOE adjusted its traditional core designs to simulate a symmetric core design

. To simulate the symmetric core design, DOE adjusted core losses, core weight, and labor costs

. While these adjustments are rough approximations, they represent potential symmetric core designs for each design line.
To adjust core losses, DOE considered several symmetric core designs, conversations with manufacturers, and published literature

. When examining the symmetric core data provided by manufacturers , DOE found that core losses for symmetric core designs range from 0

– 23 percent less than the core losses of comparable traditional transformers

. This aligns with literature published by Cha lmers University, which claims that core losses can be reduced by up to 25 percent using symmetric cores. 3 Using this data, DOE reduce d core losses by 15.5 percent for its simulated symmetric core designs, which is the mean reduction from the examined data

. DOE did not adjust the coil losses for the symmetric core designs compared to the traditional core designs.
In addition to reducing core losses, DOE reduce d the core weight in the simulated symmetric core designs

. Chalmers University literature estimate s that symmetric cores reduce the total transformer weight by 12 percent. 3 Manufacturer designs show a reduction in core weight of 15

– 25 percent compared to traditional transformer designs

. Relying on these data sources, DOE reduce d core weight by 17.5 percent for the simulated symmetric core designs , which is the mean reduction from the examined data.

DOE‘s research indicates that labor costs would increase for symmetric core designs compared to the labor requirements for comparable traditional transformer designs

. From speaking with manufacturers and examining symmetric core designs, DOE noted that labor costs may increase by 10

– 100 percent compared to th e labor costs of traditional transformer designs

. DOE increase d the labor costs of its simulated symmetric core designs by 55 percent, which is the midpoint between the 10 percent and 100 percent estimates.

3 ― Comparison B etween Hexa

- and Conventional E

- type Core Three

- Phase Transformers .‖ Available at: http://publications.lib.chalmers.se/cpl/record/index.xsql?pubid=74554

.5

- 23

Table 5.3

. 5 identifies the adjustments DOE used to simulate the symmetric core designs

. DOE appl ied these adjustments to each of the traditional three

- phase transformer designs to develop a c ost

- efficiency relatio nship for symmetric core technology

. DOE did not model a tertiary winding for the wye

- wye connected liquid

- immersed design lines

. Based on its research, DOE believes that the losses associated with the tertiary winding may offset the benefits of the symmet ric core design while also adding costs to the design

. Instead, DOE modeled symmetric core designs for the three

- phase, liquid

- immersed design lines without a tertiary winding to examine the impact of symmetric core technology on the subgroup of applicatio ns that do not require the tertiary winding.

Table 5.3

. 5 Design Adjustments for Simulated Symmetric Core Designs Range Core Losses [ W ] ( % Reduction ) Core Weight [ lbs ]

( % Reduction ) Labor Hours

( % Increase ) Minimum

- 0.0

- 12.0 +10 Mean of Observations

- 15.5

- 17.5 +55 Maximum

- 25.0

- 25.0 +100

Section 5.6 presents cost

- efficiency results for the simulated symmetric core designs

. For each three

- phase design line, DOE considered an additional efficiency level to characterize the maximum efficien cy available using symmetric core technology.
Following the preliminary analysis, DOE received more detailed design data from Hex Tec, LLC, and used in data in attempting to draw the most direct possible comparison to its conventional designs of similar d esign lines. Based on this initial treatment of the data, DOE observed a competitive, but not superior, cost/efficiency proposition for symmetric core designs. Results are presented in Appendix 5A.

5.3.3.3 Core Deactivation Technology Core deactivation technology employs a system of smaller transformers to replace a single, larger transformer

. For example, three transformers sized at 25 kVA and operated in parallel could replace a single 75 kVA transformer

. The smaller transformers that compose the system can then be activated and deactivated using core deactivation technology based on the loading demand

. Currently, DOE is not considering core deactivation systems in the context of setting standards, but may explore doing so in the future.
Winding losses are propo rtionally smaller at lower load factors, but for any given current, a smaller transformer will experience greater winding losses than a larger transformer. As a result, those losses may be more than offset by the smaller transformer‘s reduced core losses. As loading increases, winding losses become proportionally larger and eventually outweigh the power saved by using the smaller core

. At that point, the control unit (which consumes little power itself) switches on an additional transformer, reducing windin g losses at the cost of additional core losses

. The control unit knows how efficient each combination of transformers is for any given loading, and is constantly monitoring the unit‘s power output so that it will use the optimal number of cores

. In theory, there is no limit to the number of transformers that may be paralleled in this sort of system, but cost considerations would imply an optimal number.5

- 24

While core deactivation could save energy over a real world loading cycle, those savings might not be re presented in the current DOE test procedure

. Presently, the test procedure specifies a single loading point of 50 percent for liquid

- immersed and medium

- voltage dry

- type transformers, and 35 percent for low

- voltage dry

- type

. The real gain in efficiency for this technology is at loading points below the root mean square (RMS) loading specified in the test procedure, where some transformers in the system could be deactivated

. At loadings where all transformers are activated, which may be the case at the test procedure loading, the combined core and coil losses of the system of transformers could exceed those of a single, larger transformer

. This would result in a lower efficiency for the system of transformers compared to the single, larger transformer.

There fore, DOE believes core deactivation technology may be at a disadvantage in the market based on the current test procedure, which specifies a single loading based on the RMS loading in the United States

. DOE believes that the core deactivation system would engage all transformers at this loading, resulting in a lower efficiency reading than a standard, single transformer of equivalent size

. However, the core deactivation system may save more energy than the standard transformer when all loading points that are experienced in service are considered

. This is especially true for applications that have an average loading below the test procedure loading point.
DOE has not currently analyzed this technology in the engineering analysis or downstream analyses, but believes it could do so using its existing transformer designs

. To analyze this technology, DOE would consider core deactivation systems composed of three identical transformers, each wit h one

- third the kVA size of the analyzed design lines

. This creates a core deactivation system of the same total kVA size as the analyzed design lines

. Each of these core deactivation systems could be evaluated under various loading scenarios to identify the energy savings potential at loadings below and above the RMS load factor

. While it is possible to manufacture core deactivation systems using different designs for each component transformer, it requires additional design complexities

. For example, using different component transformer designs necessitates a similar win ding design to maintain the impedance across each transformer at each load factor

. These complexities would not need to be considered in the analysis when analyzing three identica l component transformer designs.
To examine each component transformer desig n, DOE could scale the engineering analysis of its existing design lines to simulate a transformer of one

- third the kVA size

. DOE would scale the losses, manufacturer selling price (MSP), weight, and dimensions using the 0.75 scaling rule explained in sect ion 5.2.2

. The resulting designs could be analyzed as component transformers for the core deactivation system

. DOE could then simulate a core deactivation system by combining three identical component transformers and considering the losses at each loading point for the following three scenarios: ( 1) all three component transformers are activated, ( 2) two component transformers are activ ated, and ( 3) only one component transformer is activated

. Given this information, DOE could simulate the performance of a core deactivation system by evaluating the scenario with the least losses for a given load factor.
Additionally, DOE would account f or the added cost and weight of the core deactivation technology

. The additional components include items such as contactors, current sensors, a5

- 25

programmable logic controller, circuit boards, additional wiring, and other miscellaneous items

. DOE estimated the cost of these components for a medium to large transformer manufacturer, and also estimat ed the incremental weight added by the components

. Table 5.3

. 6 outlines th e estimated cost and weight of the core deactivation components.

Table 5.3

. 6 Core Deactivation Technology Components, Cost and Weight Design Line 6 Design Line 7 Design Line 8 Core Deactivation Controller Cost 140 179 307 Other Components Cost [$] 237 312 882 Total Weight [lbs.] 22 50 141

DOE understands that core deactivation technology is most easily implemented in low

voltage dry

- type distribution transformer designs

. Implementing core deactivation technology in medium

- voltage distribution transformers is possible, but poses difficulties for switching the primary and secondary connections

. DOE has not fully quantified these differences, but may do so in the future if it determines that core deactivat ion technology systems are within the rulemaking scope of coverage.

5.3.4 Less

- Flammable Liquid

- Immersed Transformers For liquid

- immersed distribution transformers, DOE studied the differences between mineral oil cooled units and less

- flammable cooled units

. DO E understands that the IEEE standard C57.12.80 divides less

- flammable liquid

- immersed (LFLI) transformers into two groups: KNAN (which have an insulating liquid with a fire point greater than 300 degrees Celsius) and LNAN (which have an insulating liquid w ith no measurable fire point)

. The fire point for mineral oil is approximately 175 degrees Celsius, and therefore this type of transformer is not used inside buildings or in areas designated as hazardous

. While industry has a specification for KNAN for a c ertain degree of fire protection or LNAN for users who prefer an extra measure of safety, DOE will continue to refer to both KNAN and LNAN using the phrase  ̳less

- flammable,‘ or LFLI.
DOE understands that the viscosity of the insulating liquid can have a s light impact on the efficiency of a transformer

. When the viscosity is higher than mineral oil, transformer designers must make slightly larger cooling ducts to permit an easier flow of the fluid

. Larger ducts result in larger physical size of the winding assembly and a greater mean number of turn s of the conductor, therefore contribut ing to a slightly higher load loss. However, as efficiency increases, the transformer will run cooler, which negates part of the need for larger cooling ducts

. As such, LFLI t ransformers are still able to achieve the same efficiency levels as transformers using mineral oil

. DOE verified this fact through conversations with manufacturers and industry experts

. In fact, DOE was informed that LFLI transformers might be capable of h igher efficiencies than mineral oil units since their higher temperature tolerance may allow the unit to be downsized and run hotter than mineral oil units.
For the KNAN transformers (i.e., those with a fire point of 300 degrees or greater), DOE is not aw are of any viscosity differences with mineral oil that might impede designs or make efficiency levels significantly more difficult to reach

. For LNAN transformers (i.e., those with no5

- 26

fire point), DOE understands that the viscosity under usual operating co nditions is slightly greater than that of mineral oil, which may require design engineers to increase the duct size, leading to a marginal impact on efficiency

. However, as explained above, DOE believes this increased viscosity is offset by the cooler oper ating temperature, which could allow the transformer to be downsized and run hotter

. This would negate any impact on efficiency

. Chapter 2 provides additional discussion of less

- flammable liquid

- immersed transformers.

5.3.5 Design Line 1 Representative Unit Design line 1 (DL1) represents rectangular

- tank, liquid

- immersed, single

- phase distribution transformers, ranging from 10 kVA to 167 kVA

. The representative unit selected for this design line is a 50kVA pad

- mounted unit

. The following are the technical spe cifications that constitute input parameters to the OPS design software:
KVA: 50 (liquid

- immersed, rectangular

- tank) Primary: 14400 Volts at 60 Hz Secondary: 240/120V T Rise: 65 ̊C Ambient: 20 ̊C Winding Configuration: Lo

- Hi

- Lo (Shell

- Type) Core: Wound core

- distributed gap Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 1. 5

– 4 .5 percent
For DL1, DOE selected nine construction combinations (called ―design option combinations‖), based on input from manufacturers and other te chnical experts

. The core selected was shell

- type, because the application is for a pad

- mounted unit, and this shape is well suited to a rectangular tank

. With the exception of the max

- tech/high efficiency designs, DOE selected nine design option combinati ons to represent the most common construction practices for this representative unit

. Table 5.3

. 7 Design Option Combinations for the Representative Unit from Design Line 1
Core Material High

- Voltage Conducto r Low

- Voltage Conductor Core Design Type
M5 Cu

– wire Al

– strip Shell

– DG* Wound Core M3 Al

– wire Al

– strip Shell

– DG Wound Core M3 Cu

– wire Al

– strip Shell

– DG Wound Core M2 Al

– wire Al

– strip Shell

– DG Wound Core M2 Cu

– wire Al

– strip Shell

– DG Wound Core ZDMH Al

– wire Al

– strip Shell

– DG Wound Core ZDMH Cu

– wire Cu

– strip Shell

– DG Wound Core SA1 (Amorphous) Al

– wire Al

– strip Shell

– DG Wound Core SA1 (Amorphous) Cu

– wire Cu

– strip Shell

– DG Wound Core * DG

– Distributed gap wound core construction, where the core laminations are wound in such a way that the gap between the start and finish of a lamination is staggered in the cross

- section of the core. DOE analyzed each of the nine design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 1,924 designs.5

- 27

5.3.6 Design Line 2 Representative Unit Design line 2 (DL2) represents round

- tank, liquid

- immersed, single

- phase distribution transformers, ranging from 10 kVA to 167 kVA

. The representative unit selected for this design line is a 25kVA pole

- mounted unit

. The following are the technical specifications that constitute input parameters to the OPS design software:
KVA: 25 (liquid

- immersed, round

- tank) Primary: 14400 Volts at 60 Hz (125 kV BIL) Secondary: 120/240V T Rise: 65 ̊C Ambient: 20 ̊C Winding Configuration: Lo

- Hi

- Lo (Shell

- Type), Lo

- Hi (Core

- Type, for amorphous core) Core: Wound core

- distributed gap Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 1.0

– 4 .5 percent
For DL2, DO E selected eleven design option combinations, based on input from manufacturers and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practices for the representative unit.

Table 5.3

. 8 Design Option Combinations for the Representative Unit from Design Line 2
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M5 Cu

– wire Al

– strip Shell

– DG Wound Core M4 Al

– wire Al

– strip Shell

– DG Wound Core M 4 Cu

– wire Al

– strip Shell

– DG Wound Core M3 Al

– wire Al

– strip Shell

– DG Wound Core M3 Cu

– wire Al

– strip Shell

– DG Wound Core M2 Al

– wire Al

– strip Shell

– DG Wound Core M2 Cu

– wire Al

– strip Shell

– DG Wound Core ZDMH Al

– wire Al

– strip Shell

– DG Wound Core ZDMH Cu

– wire Cu

– strip Shell

– DG Wound Core SA1 (Amorphous) Al

– wire Al

– strip Core

– DG Wound Core SA1 (Amorphous) Cu

– wire Cu

– strip Core

– DG Wound Core DOE analyzed each of the eleven design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 2,301 designs.

5.3.7 Design Line 3 Representative Unit Design line 3 (DL3) represents round

- tank, liquid

- immersed, single

- phase distribution transformers, ranging from 250 kVA to 833 kVA

. The representative unit selected for this design line is a 500kVA round

- tank transformer

. The following are the technical specifications which constitute input parameters to the OPS design software:5

- 28

KVA: 500 (liquid

- immersed, round

- tank) Primary: 14400 Volts at 60 HZ (150kV BIL) Secondary: 277 Volts T Rise: 65  ̊ C Ambient: 20  ̊ C Winding Configuration: Lo

- Hi (Shell

- Type and Core

- Type) Core: Wound core

- distributed gap Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 1.5

– 7.0 pe rcent
For DL3, DOE selected twelve design option combinations of core steel and winding material, based on input from manufacturers and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE chose design option combinatio ns to represent the most common construction practice for this representative unit.

Table 5.3

. 9 Design Option Combinations for the Representative Unit from Design Line 3
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M5 Cu

– wire Al

– strip Shell

– DG Wound Core M4 Al

– wire Al

– strip Shell

– DG Wound Core M4 Cu

– wire Al

– strip Shell

– DG Wound Core M3 Al

– wire Al

– strip Shell

– DG Wound Core M3 Cu

– wire Al

– strip Shell

– DG Wound Core M2 Al

– wire Al

– strip Shell

– DG Wound Core M2 Cu

– wire Al

– strip Shell

– DG Wound Core ZDMH Al

– wire Al

– strip Shell

– DG Wound Core ZDMH Cu

– wire Cu

– strip Shell

– DG Wound Core SA1 (Amorphous) Al

– wire Al

– strip Core

– DG Wound Core SA1 (Amorphous) Cu

– wire Cu

– strip Shell

– DG Wound Core SA1 (Amorphous) Cu

– wire Cu

– strip Core

– DG Wound Core DOE analyzed each of the twelve design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 2,740 designs.

5.3.8 Design Line 4 Represent ative Unit Design line 4 (DL4) represents rectangular tank, liquid

- immersed, three

- phase distribution transformers, ranging from 15 kVA to 500 kVA

. The representative unit selected for this design line is a 150kVA transformer

. The following are the technical specifications that constitute input parameters to the OPS design software:
KVA: 150 (liquid

- immersed, pad mount) Primary: 12470Y/7200 Volts at 60 H z (95kV BIL) Secondary: 208Y/120 Volts T Rise: 65 ̊C Ambient: 20 ̊C Terminal Configuration: ANSI/ IEEE C57.12.26, Loop Feed5

- 29

Winding Configuration: Lo

- Hi Core: Wound core

- distributed gap, 5

- leg Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 1. 2

- 6.0 percent
For DL4, DOE selected nine design option combinations of core steel and winding types based on input from manufacturers and other technical experts

. With the exception of the max

tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practice for the repr esentative unit.

Table 5.3

. 10 Design Option Combinations for the Representative Unit from Design Line 4
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M5 Cu

– wire Al

– strip 5

- Leg DG Core M3 Al

– wire Al

– strip 5

- Leg DG Core M3 Cu

– wire Al

– strip 5

- Leg DG Core M2 Al

– wire Al

– strip 5

- Leg DG Core M2 Cu

– wire Al

– strip 5

- Leg DG Core ZDMH Al

– wire Al

– strip 5

- Leg DG Core ZDMH Cu

– wire Cu

– strip 5

- Leg DG Core SA1 (Amorphous) Al

– wire Al

– strip 5

- Leg DG Core SA1 (Amorphous) Cu

– wire Cu

– strip 5

- Leg DG Core DOE analyzed each of the nine design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 1,977 designs.

5.3.9 Design Line 5 Representative Unit Design line 5 (DL5) repre sents rectangular tank, liquid

- immersed, three

- phase distribution transformers, ranging from 750 kVA to 2500 kVA

. The representative unit selected for this design line is a 1500kVA transformer

. The following are the technical specifications that constitute input parameters to the OPS design software:
KVA: 1500 (liquid

- immersed, pad mount) Primary: 24940GrdY/14400 Volts (125kV BIL) Secondary: 480Y/277 Volts T Rise: 65 ̊C Ambient: 20 ̊C Terminal Configuration: ANSI/IEEE C57.12.26, Loop Feed Winding Configura tion: Lo

- Hi Core: Wound core

- distributed gap, 5

- leg Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 5

- 7. 5 percent
For DL5, DOE selected nine design option combinations of core steel and winding material, based on input from manufacturers and other technical experts

. With the exception of5

- 30

the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practices for the representative unit.

Table 5.3

. 11 Design Option Combinations for the Representative Unit from Design Line 5
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M4 Cu

– wire Al

– strip 5

- Leg DG Core M3 Al

– wire Al

– strip 5

- Leg DG Core M3 Cu

– wire Al

– strip 5

- Leg DG Core M2 Al

– wire Al

– strip 5

- Leg DG Core M2 Cu

– wire Al

– strip 5

- Leg DG Core ZDMH Al

– wire Al

– strip 5

- Leg DG Core ZDMH Cu

– wire Cu

– strip 5

- Leg DG Core SA1 ( Amorphous ) Al

– wire Al

– strip 5

- Leg DG Core SA1 ( Amorphous ) Cu

– wire Cu

– strip 5

- Leg DG Core DOE analyzed each of the nine design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 1,294 designs.

5.3.10 Design Line 6 Representative Unit Design line 6 (DL6) represents ventilated dry

- type, single

- phase, low

- voltage distribution transformers, ranging from 15 kVA to 333 kVA

. The representative unit selected for this design line is a 25 kVA transformer

. The following are the technical specific ations that constitute input parameters to the OPS design software:
KVA: 25 (dry

- type) Phases: Single Primary: 480 Volts at 60 Hz (10 kV BIL) Secondary: 120/240 Volts T Rise: 150 ̊C Ambient: 20 ̊C Winding Configuration: L o

- Hi (for Core

- Typ e and Shell

- Type) Core: Stacked, butt

- lap ; Wound core

- distributed gap Taps: Six 21⁄2 percent, two above and four below the nominal Impedance Range: 1.5

- 6.0 percent
For DL6, DOE selected fourteen design option combinations of core steel and winding material, based on inpu t from manufacturers and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practic e for the representative unit.5

- 31

Table 5.3

. 12 Design Option Combinations for the Representative Unit from Design Line 6
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M6 Al

– wire Al

– wire Stacked Core Butt

- lap M5 Al

– wire Al

– strip Stacked Core Butt

- lap M4 Al

– wire Al

– wire Stacked Core Butt

- lap M3 Al

– wire Al

– strip Stacked Core Butt

- lap M3 Al

– wire Al

– strip Core

– Step

- Lap Miter M3 Al

– wire Al

– strip Core

– DG Wound Core M3 Cu

– wire Al

– wire Stacked Core Butt

- lap M3 Cu

– wire Al

– wire Stacked Shell Butt

- lap H

- 0 DR* Al

– wire Al

– strip Stacked Core Butt

- lap H

- 0 DR Al

– wire Al

– strip Core

– Step

- Lap Miter H

- 0 DR Cu

– wire Cu

– wire Stacked Core Butt

- lap ZDMH Al

– wire Al

– strip Core

– DG Wound Core SA1 (Amorphous) Al

– wire Al

– strip Core

– DG Wound Core SA1 (Amorphous) Cu

– wire Cu

– wire Core

– DG Wound Core * H

- 0 DR is a domain

- refined, high permeability core steel. DOE analyzed each of the fourteen design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 4,298 designs.

5.3.11 Design Line 7 Representative Unit Design line 7 (DL7) represents ventilated dry

- type, three

- phase, low

- voltage distribution transformers, ranging from 15 kVA to 150 kVA

. The representative unit selected for this design line is a 75 kVA transformer

. The following are the technical specifications that constitute input parameters to the OPS design software:
KVA: 75 (dry

- type) Phases: Three Primary: 480 Volts at 60 Hz (10 kV BIL) Secondary: 208Y/120 Volts T Rise: 150 ̊C Ambient: 20 ̊C Winding Configuration: Lo

- Hi Core: Stacked, butt

- lap; Stacked, mitered ; Wound core

- distributed gap Taps: Six 21⁄2 percent, two above and four below the nominal Impedance Range: 1.5

– 6.0 percent
For DL7, DOE selected fourteen design option combinations of core steel and winding material, based on input from manufacturers and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most co mmon construction practice for the representative unit.5

- 32

Table 5.3

. 13 Design Option Combinations for the Representative Unit from Design Line 7
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M12 Al

– wire Al

– wire 3

- Leg Stacked Butt

- lap M12 Cu

– wire Al

– wire 3

- Leg Stacked Butt

- lap M6 Al

– wire Al

– wire 3

- Leg Stacked Butt

- lap M6 Al

– wire Al

– wire 3

- Leg Stacked Full Miter** M4 Cu

– wire Al

– wire 3

- Leg Stacked Full Miter M3 Al

– wire Al

– wire 3

- Leg Stacked Full Miter M3 Al

– wire Al

– wire 3

- Leg Step

- Lap Miter M3 Al

– wire Al

– wire 3

- Leg DG Core H

- 0 DR * Al

– wire Al

– strip 3

- Leg Stacked Full Miter H

- 0 DR Al

– wire Al

– strip 3

- Leg Step

- Lap Miter ZDMH Al

– wire Al

– strip 3

- Leg DG Core H

- 0 DR Cu

– wire Cu

– wire 3

- Leg Stacked Full Miter SA1 (Amorphous) Al

– wire Al

– strip 5

- Leg DG Core SA1 (Amorphous) Cu

– wire Cu

– wire 5

- Leg DG Core * H

- 0 DR is a domain

- refined, high permeability core steel. ** Full miters are not step

- miters, but are mitered joints for all three legs

. These cores are stacked three by three. DOE analyzed each of the fourteen design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 4,165 designs.

5.3.12 Design Line 8 Representative Unit Design line 8 (DL8) repre sents ventilated dry

- type, three

- phase, low

- voltage distribution transformers, ranging from 225 kVA to 1000 kVA

. The representative unit selected for this design line is a 300 kVA transformer

. The following are the technical specifications that constitute input parameters to the OPS design software:
KVA: 300 (dry

- type) Phases: Three Primary: 480V at 60 Hz (10 kV BIL) Delta Connected Secondary: 208Y/120 Volts T Rise: 150 ̊C Ambient: 20 ̊C Winding Configuration: Lo

- Hi Core: Stacked, butt

- lap; Stacked, mitered ; Wound core

- distributed gap Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 3.0

– 7

. 0 percent
For DL8, DOE selected fifteen design option combinations of core steel and winding material, based on input from manufacturer s and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practice for the representative unit.5

- 33

Table 5.3

. 14 Design Option Combinations for the Representative Unit from Design Line 8
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M6 Al

– wire Al

– strip 3

- Leg Stacked Butt

- lap M6 Cu

– wire Cu

– strip 3

- Leg Stacked Full Miter** M5 Al

– wire Al

– strip 3

- Leg Stacked Butt

- lap M5 Al

– wire Al

– strip 3

- Leg Stacked Full Miter M4 Cu

– wire Al

– strip 3

- Leg Stacked Full Miter M3 Al

– wire Al

– strip 3

- Leg Stacked Full Miter M3 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter M3 Al

– wire Al

– strip 3

- Leg DG Core M3 Cu

– wire Al

– strip 3

- Leg Stacked Full Miter H

- 0 DR * Al

– wire Al

– strip 3

- Leg Stacked Full Miter H

- 0 DR Al

– wire Al

– strip 5

- Leg Step

- Lap Miter ZDMH Al

– wire Al

– strip 5

- Leg DG Core H

- 0 DR Cu

– wire Cu

– strip 3

- Leg Stacked Full Miter SA1 (Amorphous) Al

– wire Al

– strip 5

- Leg DG Core SA1 (Amorphous) Cu

– wire Cu

– strip 5

- Leg DG Core * H

- 0 DR is a domain

- refined, high permeability core steel. ** Full miters are not step

- miters, but are mitered joints for all three legs

. These cores are stacked three by three. DOE analyzed each of the fifteen design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 4,557 designs.

5.3.13 Design Line 9 Representative Unit Design line 9 (DL9) represents ventilated dry

- type, three

- phase, medium

- voltage distribution transformers with a 20

- 45kV BIL, ranging from 15 kVA to 500 kVA

. The representative unit selected for this design line is a 300 kVA transformer

. The following are the technical specifications that constitute input parameters to the OPS design software:
KVA: 300 (dry

- type) Phases: Three Primary: 4160V at 60 Hz (45 kV BIL) Delta Connected Secondary: 480Y/277 Volts T Rise: 150 ̊C Ambient: 20 ̊C Winding Configuration: Lo

- Hi Core: Stacked, mitered ; Wound core

- distributed gap Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 3.0

– 7 .0 percent
For DL9, DOE selected thirteen design option combinations of core steel and winding material, based on input from manufacturers and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practice for the representative unit

.5

- 34

Table 5.3

. 15 Design Option Combinations for the Representative Unit from Design Line 9
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M6 Cu

– wire Cu

– wire 3

- Leg Stacked Full Miter** M5 Al

– wire Al

– wire 3

- Leg Stacked Full Miter M3 Al

– wire Al

– strip 3

- Leg Stacked Full Miter M3 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter M3 Al

– wire Al

– strip 5

- Leg DG Core M3 Cu

– wire Al

– strip 3

- Leg Stacked Full Miter H

- 0 DR* Al

– wire Al

– strip 3

- Leg Stacked Full Miter H

- 0 DR Al

– wire Al

– strip 3

- Leg Step

- Lap Miter ZDMH Al

– wire Al

– strip 5

- Leg DG Core H

- 0 DR Cu

– wire Cu

– strip 3

- Leg Stacked Full Miter SA1 (Amorphous) Al

– wire Al

– strip 5

- Leg DG Core SA1 (Amorphous) Cu

– wire Cu

– strip 3

- Leg DG Core SA1 (Amorphous) Cu

– wire Cu

– strip 5

- Leg DG Core * H

- 0 DR is a domain

- refined, high permeability core steel. ** Full miters are not step

- miters, but are mitered joints for all three legs

. These cores are stacked three by three. DOE analyzed each of the thirteen design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 5,948 designs.

5.3.14 Design Line 10 Representative Unit Design line 10 (DL10) re presents dry

- type, three

- phase, medium

- voltage distribution transformers with a 20

- 45kV BIL, ranging from 750 kVA to 2500 kVA

. The representative unit selected for this design line is a 1500 kVA transformer

. The following are the technical specifications t hat constitute input parameters to the OPS design software:
KVA: 1500 (dry

- type) Phases: Three Primary: 4160V at 60 Hz (45 kV BIL) Secondary: 480Y/277 Volts T Rise: 150 ̊C Ambient: 20 ̊C Winding Configuration: Lo

- Hi Core: Stacked, cruciform, mitered joint , 3

- leg ; Wound core

- distributed gap Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 5.0

- 8 .0 percent
For DL10, DOE selected ten design option combinations of core steel and winding material, based on input from manufacturers and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practice for the representative unit.5

- 35

Table 5.3

. 16 Design Option Combinations for the Representative Unit from Design Line 10
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M5 Cu

– wire Al

– strip 3

- Leg Mitered Cruciform M4 Cu

– wire Al

– strip 3

- Leg Mitered Cruciform M3 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M3 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter M3 Cu

– wire Cu

– strip 3

- Leg Mitered Cruciform H

- 0 DR* Al

– wire Al

– strip 3

- Leg Mitered Cruciform H

- 0 DR Al

– wire Al

– strip 3

- Leg Step

- Lap Miter H

- 0 DR Cu

– wire Cu

– strip 3

- Leg Mitered Cruciform SA1 (Amorphous) Al

– wire Al

– strip 5

- Leg DG Core SA1 (Amorphous) Cu

– wire Cu

– strip 3

- Leg DG Core * H

- 0 DR is a domain

- refined, high permeability core steel. DOE analyzed each of the ten design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 2,369 designs.

5.3.15 Design Line 11 Representative Unit Design line 11 (DL11) represents dry

- type, three

- phase, medium

- voltage distribution transformers with a 46

- 95kV BIL, ranging from 15 kVA to 500 kVA

. The representative unit selected for this design line is a 300 kVA transformer

. The following are the technical specifications that constitute input parameters to the OPS design software:
KVA: 300 (dry

- type) Phases: Three Primary: 12470 Volts at 60 Hz (95 kV BIL) Secondary: 480Y/277 Volts T Rise: 150 ̊C Ambient: 20 ̊C Winding Configuration: Lo

- Hi Core: Stacked, mitered joint , 3

- leg; Wound core

- distributed gap, 5

- leg Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 3.0

- 7.0 percent
For DL11, DOE selected eleven design option combinations of core steel and winding material, based on input from manufacturers and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE selected these desi gn option combinations to represent the most common construction practice for the representative unit

. Table 5.3

. 17 Design Option Combinations for the Representative Unit from Design Line 11
Core Material Hi gh

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M6 Cu

– wire Cu

– strip 3

- Leg Stacked Full Miter** M4 Cu

– wire Al

– strip 3

- Leg Stacked Full Miter M3 Al

– wire Al

– strip 3

- Leg Stacked Full Miter M3 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter5

- 36

M3 Cu

– wire Cu

– strip 3

- Leg Stacked Full Miter H

- 0 DR* Al

– wire Al

– strip 3

- Leg Stacked Full Miter H

- 0 DR Al

– wire Al

– strip 3

- Leg Step

- Lap Miter ZDMH Al

– wire Al

– strip 3

- Leg DG Core H

- 0 DR Cu

– wire Cu

– strip 3

- Leg Stacked Full Miter SA1 (Amorphous) Al

– wire Al

– strip 3

- Leg DG Core SA1 (Amorphous) Cu

– wire Cu

– strip 5

- Leg DG Core * H

- 0 DR is a domain

- refined, high permeability core steel. ** Full miters are not step

- miters, but are mitered joints for all three legs

. These cores are stacked three by three. DOE analyzed each of the eleven design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 2,035 designs.

5.3.16 Design Line 12 Representative Unit Design line 12 (DL12) represents dry

- type, three

- phase, medium

- voltage distribution transformers with a 46

- 95kV BIL, ranging from 750 kVA to 2500 kVA

. The representative unit selected for this design line is a 1500 kVA transformer

. The following are the technical specifications that constitute input parameters to the OPS design software:

KVA: 1500 (dry

- type) Phases: Three Primary: 12470 Volts at 60 Hz (95 kV BIL) Secondary: 480Y/277 Volts T Rise: 150 ̊C Ambient: 20 ̊C Winding Configuration: Lo

- Hi Core: Stacked, cruciform, mitered joint , 3

- leg ; Wound core

- distributed gap, 5

- leg Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 5.0

– 8.0 percent
For DL12, DOE selected eleven design option combinations of core steel and winding material, based on input from manufacturers and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practice for the representative unit

. Table 5.3

. 18 Design Option Combinations fo r the Representative Unit from Design Line 12
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M6 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M5 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M4 Cu

– wire Al

– strip 3

- Leg Mitered Cruciform M3 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M3 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter M3 Cu

– wire Cu

– strip 3

- Leg Mitered Cruciform H

- 0 DR* Al

– wire Al

– strip 3

- Leg Mitered Cruciform H

- 0 DR Al

– wire Al

– strip 3

- Leg Step

- Lap Miter H

- 0 DR Cu

– wire Cu

– strip 3

- Leg Mitered Cruciform SA1 (Amorphous) Al

– wire Al

– strip 5

- Leg DG Core5

- 37

SA1 (Amorphous) Cu

– wire Cu

– strip 5

- Leg DG Core * H

- 0 DR is a domain

- refined, high permeability core steel. DOE analyzed each of the eleven design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 3,243 designs.

5.3.17 Design Line 13 A Representative Unit Design line 13 A (DL13 A ) represents dry

- type, three

- phase, medium

- voltage distribution transformers with a ≥96kV BIL, ranging from 225 kVA to 2500 kVA

. The representative unit selected for this design line is a 300 kVA transformer

. The following are the technical specifications that constitute input parameters to the OPS design software:

KVA: 300 (dry

- type) Phases: Three Primary: 24940 Volts at 60 Hz (125 kV BIL) Secondary: 480Y/277 Volts T Rise: 150 ̊C Ambient: 20 ̊C Winding Configuration: Lo

- Hi Core: Stacked, cruciform, mitere d joint , 3

- leg ; Wound core

- distributed gap, 5

- leg Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 3 .0

– 7.0 percent

For DL13 A , DOE selected seven design option combinations of core steel and winding material, based on input from manufacturers and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practice for the representative unit

. Table 5.3

. 19 Design Option Combinations for the Representative Unit from Design Line

13 A
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M 5 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M 4 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M 3 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M 3 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter H

- 0 DR * Al

– wire Al

– strip 3

- Leg Mitered Cruciform ZDMH Al

– wire Al

– strip 3

- Leg DG Core SA1 (Amorphous) Al

– wire Al

– strip 5

- Leg DG Core * H

- 0 DR is a domain

- refined, high permeability core steel. DOE analyzed each of the seven design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 919 designs.5

- 38

5.3.18 Design Line 13B Representative Unit Design line 13B (DL13B) also represents dry

- type, three

- phase, medium

- voltage distribution transformers with a ≥96kV BIL, ranging from 225 kVA to 2500 kVA

. The representative unit selected for this design line is a 2000 kVA transformer

. The following are t he technical specifications that constitute input parameters to the OPS design software:
KVA: 2000 (dry

- type) Phases: Three Primary: 24940 Volts at 60 Hz (125 kV BIL) Secondary: 480Y/277 Volts T Rise: 150 ̊C Ambient: 20 ̊C Winding Configuration: Lo

- Hi Core : Stacked, cruciform, mitered joint, 3

- leg ; Wound core

- distributed gap, 5

- leg Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 5.0

– 8 .0 percent

For DL13 B , DOE selected seven design option combinations of core steel and winding material, based on input from manufacturers and other technical experts

. With the exception of the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practice for the representative un it

. Table 5.3

. 20 Design Option Combinations for the Represen tative Unit from Design Line

13 B
Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type
M 5 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M 4 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M 3 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M 3 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter H

- 0 DR* Al

– wire Al

– strip 3

- Leg Mitered Cruciform H

- 0 DR Al

– wire Al

– strip 3

- Leg Step

- Lap Miter SA1 (Amorphous) Al

– wire Al

– strip 5

- Leg DG Core * H

- 0 DR is a domain

- refined, high permeability core steel. DOE analyzed each of the seven design option combinations using the matrix of A and B values described in Table 5.3

. 1 and Tabl e 5.3

. 2 , creating 1,848 designs.

5.3.19 Newly Optimized Designs and Previously Optimized Designs DOE utilized a combination of newly optimized design runs and designs that were optimized during the prelim inary analysis for distribution transformers

. For each design option combination chosen, DOE generates designs based on 518 A and B factor combinations

. These A and B factor combinations cover the spectrum of typical load loss and no

- load loss valuations, generating a unique design across a range of efficiencies.5

- 39

DOE understands that typically a design would be optimized based on the current material prices

. Optimizing a design based on historical material prices may result in a differently optimized design, such as a design that utilizes relatively more conductor than core

. However, DOE believes that it adequately covered the spectrum of possible designs for each design option combination used in the preliminary analysis based on the large sample of A and B factor combinations considered for each design option combination

. As such, DOE believes that these designs are still valid when updated material prices are applied to them.
DOE updated the cost of these previous design runs by applying updated pri ces to the design‘s bill of materials

. Effectively, DOE calculated the present cost of developing the same design that was used in the previous rulemaking

. DOE also updated labor prices and applied the markups consistently with any newly optimized designs generated for the analysis.
While DOE believes that its approach of reusing previously optimized designs with updated material prices is reasonable, it plans to create newly optimized designs for the analysis as well

. Currently, DOE has added in several new design option combinations, which are modeled with a newly optimized design

. Additionally, DOE may choose to re

- optimize the designs from the preliminary analysis rather than simply updating their material pric es as the analysis progresses

.

5.4 MATERIAL A ND LABOR INPUTS DOE uses a standard method of cost accounting with minor changes to determine the costs associated with manufacturing

. This methodology is illustrated in Figure 5.4

. 1 , where production costs and non

- production costs are combined to determine the manufacturer‘s selling price of the equipment

.5

- 40

Figure 5.4

. 1 Method of Cost Accounting for Distribution Trans formers Rulemaking
The full production cost and the non

- production cost equal the manufacturer‘s selling price of the equipment

. Full production cost is a combination of direct labor, direct materials, and overhead

. The overhead contributing to full production cost includes indirect labor, indirect material, maintenance, depreciation, taxes, and insurance related to company assets

. Non

production cost includes the cost of selling , general and administrative items (market research, advertising, sales r epresentatives, logistics), research and development (R&D), interest payments, warranty and risk provisions, shipping, and profit factor

. Because profit factor is included in the non

- production cost, the sum of production and non

- production costs is an est imate of the manufacturer‘s selling price.

DOE used several estimates of the costs listed in Figure 5.4

. 1 from DOE‘s previous rulemaking on distribution transformers , published in October 2007

. The estimates from this rulemaking relied on U.S. Industry Census Data Reports, manufacturer interviews, and Securities and Exchange Commission (SEC) 10

- K reports for several manufacturers

. It then refined these estimates throu gh meetings and dialogue with transformer manufacturers in 2010

. The following markups resulted:
Scrap and handling factor: 2.5 percent markup

. This markup applies to variable materials (e.g., core steel, windings, i n sulation)

. It accounts for the handli ng of material (loading into assembly or winding equipment) and the scrap material that cannot be used in the production of a finished transformer (e.g., lengths of wire too short to wind, trimmed core steel).
Amorphous scrap factor: 1.5 percent markup

. This markup a ccounts for breakage of prefabricated amorphous cores and any scrap associated with assembling the windings on the core

. Since amorphous cores are considered to be prefabricated, the regular scrap and handling factor is reduced

. Full Cost of Product

Full Production Cost

Direct Labor Direct

Material Overhead

Indirect Labor
Indirect Material
Maintenance Depreciation

Taxes

Insurance related to assets Non

- Production Cost

Selling, General & Admin.

Mkt. research Advertising
Point of Sale promotion
Cust. service Sales person salary + travel + commission Logistics R & D

Costs associated with efforts to find
new or improved products or production processes
Code Compliance
Modernization Interest

Costs of borrowing funds Warranty

& Risk Shipping

Costs of freight for final delivery Profit5

- 41

Mitered scrap factor: 4.0 percent markup

. An additional scrap markup applies to steel used in full

- mitered cores

. This markup represents material cut from the notch in the yoke.
Factory overhead: 12.5 percent markup

. Factory overhead includes all the indirect costs associated with production, indirect materials and energy use (e.g., annealing furnace), taxes, and insurance

. DOE only applied factory overhead to the direct material production costs. Shipping: $0.2 8 per pound for each transformer

. The shipping costs include the freight from a manufacturer‘s facility to the customer

. This shipping cost does not include any freight charges for the customer to subsequently move the transformer to its end

- use location

. DOE applied the shipping charge prior to applying the profit markup based on feedback from manufacturer interviews in 201 1

.
Non

- production: 25 percent markup

. This markup reflects costs including selling, general and administrative, R&D, interest payments, warranty and risk provisions, and profit factor

. D OE applied the non

- production markup to the sum of direct material, direct labor, and factory overhead.
The following example shows how DOE applied the markups to the materials, and how it determined the manufacturer selling price

. Consider a 300kVA 45kV BIL three

- phase, dry

- type transformer designed with a $1.50 A and a $0.30 B

. This design has $ 4,795 of materials, including M6 core steel, copper primary and secondary windings, and all the transformer hardware

. There are approximately 27 hours of labor in volved in manufacturing this design, resulting in a labor cost of $ 1,3 67

. The factory overhead on this design is $ 599 , as it is only applied to the material cost (i.e., 12.5 percent of $ 4, 795 )

. The shipping cost is $ 50 4 , based on a weight of 1,792 pounds

. The non

- production cost is $ 1, 706 , since the 25 percent is applied to the material, labor, factory overhead , and shipping costs (i.e., 25 percent of $ 4, 795 + $ 1,3 91 + $ 599 + $ 504 )

. Thus, in total, DOE estimates this 300kVA three

- phase transformer to have a manufacturer selling price of $ 9, 033

.

5.4.1 Material Prices DOE used prices of core steel, conductor, mineral oil, insulation, and other materials as an input to the transformer design software used for the engineering analysis

. As the price of one material increases or decreases relative to the other materials, the software will modify its design and increase or decrease the amount of that material while balancing other design parameters, creating a cost

- optimized transformer

. Material pricing is also critic al because the manufacturer‘s selling prices calculated in the engineering analysis are based on a bill of materials that includes specifications for pounds of steel, pounds of conductor, gallons of mineral oil, tank dimensions, and so on

. Therefore, as ma terial prices increase, so will the manufacturer‘s selling price

. Furthermore, as discussed in Chapter 3, energy

- efficient transformers tend to incorporate more5

- 42

materials (e.g., pounds of core steel, pounds of conductor), making the impact of more expensiv e materials even more significant at higher efficiencies.
DOE contracted OPS to develop material price estimates for the engineering analysis

. OPS used data from their own records as well as data provided by transformer manufacturers and material supplier s and wholesalers

. Although not all transformer manufacturers pay the same amount per pound for electrical

- grade steels, due to varied contract negotiations, these prices are intended to be representative of a standard quantity order for a medium

- to large

- scale U.S. transformer manufacturer

. DOE supplemented that price data by aggregating information obtained during interviews with manufacturers of distribution transformers. After the preliminary analysis, DOE received feedback that volatility in the cond uctor commodities markets made it difficult to consider any price accurate for any length of time because the rate of price movement was high relative to typical purchase contract terms.
DOE received feedback that a more accurate way to develop conductor prices would be to establish a processing ―adder,‖ or cost required to form the finished good from underlying commodity. The adder would change much more slowly in time than the price of the processed commodity, and would allow derivation of conductor pric es by summing the processing adder and the price of the underlying commodity in exchanges such as COMEX and London Metal Exchange. DOE intends to continue deriving conductor prices in this manner in future updates to the analysis.
DOE conducted the engine ering analysis using material prices over a five

- year time period from 2006

- 2010, all in constant 2010$

. Using the material prices from this time period, DOE considered a current (2010) material price, a minimum price (based on 2006 prices), and a maximum price (based on 2008 prices) for its analysis

. This was done to account for variation in pricing for the different materials, which could have a significant impact on the total cost of the distribution transformer

. All transformer designs that were newly o ptimized used the current 20 10 material price, which DOE used as its reference case

. The maximum and minimum prices were then applied to these same designs to generate a manufacturer selling price for each of those scenarios

. The results of the current 201 0 material prices are presented here in Chapter 5, while the results of the minimum and maximum material prices are presented in Appendix 5C.
DOE noted that the price of the most critical material input to a distribution transformer, electrical core steel , had varied significantly for some M

- grades over the five

- year time horizon (see Table 5.4

. 1 )

. For this reason, DOE researched the grain

- oriented electrical steel mar ket to gain a better understanding of the main players and some of the factors influencing these price fluctuations (see Appendix 3A)

. In the LCC analysis (Chapter 8), DOE presents results on its sensitivity analyses conducted on various LCC inputs, whic h included material prices

. In Chapter 8, the 2008 material price scenario is referred to as the ―high‖ price scenario , the 2010 price scenario is called the ―medium‖ price scenario , and the 2006 material price scenario is referred to as the ―low‖ price scenario

. DOE chose to utilize the current 2010 material price in the reference case5

- 43

after receiving feedback from transformer manufacturers and suppliers of core steel indicating that current prices would be a better price indicator than a five

- year avera ge price

. These material prices can be found in the material price tables presented in this section

. The resulting manufacturer selling prices are provided in the LCC spreadsheets.

5.4.2 Material Inputs to the Design Software

– Liquid

- Immersed

Table 5.4

. 1 presents the material prices for a typical manufacturer of liquid

- immersed transformers over the five

- year 2006

- 2010 time horizon , indicating the current , minimum, and maximum prices (all in constant 20 10 $)

. The highlighted columns are the prices that DOE used in the engineering analysis.5

- 44

Table 5.4

. 1 Typical Manufacturer’s Material Prices for Liqu id

- Immersed Design Lines

Material Units 2010 Price 2010$ Min.

Price (2006

– 25%) 2010$ Max.

Price (2008
+ 25%) 2010$ 2010 2010$ 2009 2010$ 2008 2010$ 2007 2010$ 2006 2010$

M6 core steel $/lb $ 1.46 $ 0.94 $

2.19 $ 1.46 $ 1.64 $ 1.75 $ 1.58 $ 1.26 M5 core steel $/lb $ 1.51 $ 0.99 $

2.24 $ 1.51 $ 1.67 $ 1.79 $ 1.61 $ 1.32 M4 core steel $/lb $ 1.59 $

1.03 $ 2.30 $ 1.59 $ 1.70 $ 1.84 $ 1.64 $ 1.38 M3 core steel $/lb $ 1.88 $

1.06 $ 2.60 $ 1.88 $ 1.96 $ 2.08 $ 1.70 $ 1.41 M3 core steel (Lite Carlite) $/lb $ 1.95 $

1.47 $ 2.44 $ 1.95 $

- $

- $

- $

- M2 core steel $/lb $ 2.00 $

1.32 $ 2.79 $ 2.00 $ 2.01 $ 2.23 $ 2.18 $ 1.76 M2 core steel (Lite Carlite) $/lb $ 2.10 $

1.58 $ 2.63 $ 2.10 $

- $

- $

- $

- ZDMH (mechanically

scribed core steel) $/lb $ 2.05 $

1.41 $ 3.22 $ 2.05 $ 2.02 $ 2.57 $ 2.29 $ 1.88 SA1 (amorphous) finished core, volume production $/lb $ 2.38 $

1.72 $ 3.64 $ 2.38 $ 2.29 $ 2.91 $

- $

- Copper wire, formvar, round #10

- 20 $/lb $ 4.87 $

3.33 $

5.97 $ 4.87 $ 3.81 $ 4.77 $ 4.78 $ 4.44 Copper wire, enameled, round #7

- 10 $/lb $ 4.84 $

3.31 $

5.93 $ 4.84 $ 3.78 $ 4.74 $ 4.75 $ 4.41 Copper wire, enameled, rectangular sizes $/lb $ 4.97 $

3.41 $

6.09 $ 4.97 $ 3.91 $ 4.87 $ 4.88 $ 4.54 Aluminum wire, formvar, round #9

- 17 $/lb $ 3.07 $

2.30 $

3.91 $ 3.07 $ 3.00 $ 3.13 $ 3.08 $ 3.07 Aluminum wire, formvar, round #7

- 10 $/lb $ 2.57 $

1.93 $ 3.28 $ 2.57 $ 2.50 $ 2.63 $ 2.58 $ 2.57 Copper strip, thickness range 0.02

- 0.045 $/lb $ 4.97 $

3.41 $

6.09 $ 4.97 $ 3.91 $ 4.87 $ 4.88 $ 4.54 Copper strip, thickness range 0.030

- 0.060 $/lb $ 4.97 $

3.41 $

6.09 $ 4.97 $ 3.91 $ 4.87 $ 4.88 $ 4.54 Aluminum strip, thickness range 0.02

- 0.045 $/lb $ 2.08 $

1.56 $ 2.67 $ 2.08 $ 2.01 $ 2.14 $ 2.09 $ 2.08 Aluminum strip, thickness range 0.045

- 0.080 $/lb $ 2.08 $

1.56 $ 2.67 $ 2.08 $ 2.01 $ 2.14 $ 2.09 $ 2.08 Kraft insulating paper with diamond adhesive $/lb $ 1.52 $

1.17 $

1.93 $ 1.52 $ 1.54 $ 1.54 $ 1.56 $ 1.56 Mineral oil $/gal $ 3.35 $

1.94 $ 3.84 $ 3.35 $ 2.89 $ 3.07 $ 2.51 $ 2.59 Tank Steel $/lb $ 0.38 $

0.32 $

0.60 $ 0.38 $ 0.39 $ 0.48 $ 0.43 $ 0.43 DOE then marked up the raw material prices presented in Table 5.4

. 1 using the manufacturer‘s internal markups discussed in section 5.4.1

. DOE used the marked

- up material prices as inputs to the transformer design software for optimization, even though the material prices do not receive the markup during DOE‘s cost calculation

. The cost calculation applies the5

- 45

markups to the total material cost

. During its manufacturer site visits in 2010 , DOE found this approach to be consistent with that of several manufacturers who operate their own, proprietary transformer design software

. F or example, a raw material price of $1.00/lb. would be marked up to $1.44/lb., reflecting the handling and scrap factor (2.5 percent), the factory overhead (12.5 percent), and the non

- production markup (25 percent)

. DOE did not include shipping costs as a markup of the raw material because these costs were based on the weight of the design, not a percentage markup

. Table 5.4

. 2 shows the markup steps bein g applied to the current 2010 material price scenario.5

- 46

Table 5.4

. 2 Marked

- up Material Prices for Liquid

- Immersed Units, Current Year (2010)

Price Scenario
Item and Description Units Current 2010 Price 2010$ Scrap & Handling Factory

Overhead Non

Product ion Software

Input

M6 core steel $/lb $ 1.46 1.025 1.125 1.25 $ 2.10
M5 core steel $/lb $ 1.51 1.025 1.125 1.25 $ 2.18
M4 core steel $/lb $ 1.59 1.025 1.125 1.25 $ 2.28
M3 core steel $/lb $ 1.88 1.025 1.125 1.25 $ 2.70 M3 core steel (Lite Carlite) $/lb $ 1.95 1.025 1.125 1.25 $ 2.82
M2 core steel $/lb $ 2.00 1.025 1.125 1.25 $ 2.88 M2 core steel (Lite Carlite) $/lb $ 2.10 1.025 1.125 1.25 $ 3.03 ZDMH (mechanically

- scribed core steel) $/lb $ 2.05 1.025 1.125 1.25 $ 2.95 SA1 (amorphous) finished core, volume production $/lb $ 2.38 1.015 1.125 1.25 $ 3.40 Copper wire, formvar, round #10

- 20 $/lb $ 4.87 1.025 1.125 1.25 $ 7.02 Copper wire, enameled, round #7

- 10 $/lb $ 4.84 1.025 1.125 1.25 $ 6.98 Copper wire, enameled, rectangular sizes $/lb $ 4.97 1.025 1.125 1.25 $ 7.17 Aluminum wire, formvar, round #9

- 17 $/lb $ 3.07 1.025 1.125 1.25 $ 4.43 Aluminum wire, formvar, round #7

- 10 $/lb $ 2.57 1.025 1.125 1.25 $ 3.71 Copper strip, thickness range 0.02

- 0.045 $/lb $ 4.97 1.025 1.125 1.25 $ 7.17 Copper strip, thickness range 0.030

- 0.060 $/lb $ 4.97 1.025 1.125 1.25 $ 7.17 Aluminum strip, thickness range 0.02

- 0.045 $/lb $ 2.08 1.025 1.125 1.25 $ 3.00 Aluminum strip, thickness range 0.045

- 0.080 $/lb $ 2.08 1.025 1.125 1.25 $ 3.00 Kraft insulating paper with diamond adhesive $/lb $ 1.52 1.025 1.125 1.25 $ 2.18
Mineral oil $/gal $ 3.35 1.000 1.125 1.25 $ 4.71
Tank Steel $/lb $ 0.38 1.025 1.125 1.25 $ 0.555

- 47

The price used for a prefabricated amorphous core is based on prices of finished cores from North American manufacturers

. In the previous rulemaking for distribution transformers, DOE analyzed the cost importing finished cores from overseas

. Since that time, several North American core manufacturers have begun producing amorphous cores

. For the preliminary analysis, DOE considered the price of a prefabricated amorphous core bought from a North American core manufacturer.
In addition to the aforementioned materials that vary during the design optimization process (e.g., core steel, windings, insulation), there are other direct materials inputs that are fixed costs and generally do not influence the design or vary with efficiency rating

. These include direct materials, such as the high

- and low

- voltage bushings and the core clamps

. DOE also prepared estimates of the tank fabrication cost, based on the optimized transformer design (the software con siders this variable) and the labor necessary to build the tank

. Table 5.4

. 3 summarizes all the estimated fixed material costs and estimates of the ta nk costs for each of the five liquid

- immersed design lines.
For DL1, a 50kVA single

- phase pad

- mounted unit, the high

- voltage bushings are two universal bushing wells, 15 kV, 95 BIL, 14400V, costing $ 14 each

. The low

- voltage bushings are three threaded cop per studs, 240/120V, 50 kVA, costing $ 3 0 for the set

. Internal hardware costs include a core clamp, nameplate, and other miscellaneous hardware costing $ 41 .65

. The finished tank size (and associated cost) varies by design, but the average cost is approxima tely $ 143

. For DL2, a 25kVA single

- phase pole

- mounted unit, the high

- voltage terminal is a single, wet

- process porcelain bushing assembly, 15 kV, 125 BIL, costing $6

. The low

- voltage terminals are three molded polymer bushings, 120/240V, 25 kVA, costing $ 8 for the set

. Internal hardware costs include a core clamp, nameplate, and other miscellaneous hardware, costing $19.15

. The finished tank sizes (height and diameter) vary by design, but the average cost is approximately $ 7 3

. For DL3, a 500kVA single

- pha se unit, the high

- voltage connector is a single, wet

- process porcelain bushing, 25 kV, 125 BIL, costing $6

. The low

- voltage bushings are two four

- hole ―J‖ Spade 500kVA, 277V, costing $60 for the set

. The internal hardware includes a core clamp ($30), namep late ($0.65), and miscellaneous hardware ($20), totaling $50.65

. The design software optimized the tank cost with each design, including radiators (external cooling) for this kVA rating

. The resultant finished round tank has a diameter of 33" to 52", with an average cost of approximately $ 62 9 (including radiators).
For DL4, a 150kVA three

- phase, pad

- mounted unit, the high

- voltage bushings are three externally clamped, universal high

- voltage bushing wells, 8.3/14.4 kV, 95 BIL, costing $7 each

. The low

- volta ge bushings are three copper studs at $8 each

. The internal hardware includes core clamps ($30), nameplate ($0.65), and miscellaneous hardware ($45), totaling $75.65

. The optimized finished tank sizes measure 50 inches high and vary in width and depth

. The finished rectangular, welded tank has an average cost of approximately $ 38 9

.5

- 48

For DL5, a 1500kVA three

- phase, pad

- mounted unit, the high

- voltage bushings are three externally clamped, universal high

- voltage bushing wells, 15.2/26.3 kV, 125kV BIL, costing $20 each

. The low

- voltage bushings are four externally clamped bushings, each having six

- hole spade, costing $160 for the set

. The internal hardware includes core clamps ($60), nameplate ($0.65), and miscellaneous hardware ($45), totaling $105.65

. The optimized finished tank sizes measure 70 inches high and vary in width and depth

. The finished rectangular, welded tank, including radiators as specified by the design software, has an average cost of approximately $ 1,01 6

. Table 5.4

. 3 Summary Table of Fixed Material Costs for Liquid

- Immersed Units Item DL1 DL2 DL3 DL4 DL5 High voltage bushings $ 28 $6 $6 $21 $60 Low voltage bushings $ 3 0 $8 $60 $24 $160 Core clamp, nameplate, and misc. hardware $ 41 .65 $19.15 $50.65 $75.65 $105.65 Transformer tank average cost* ~$ 143 ~$ 73 ~$ 62 9 ~$ 38 9 ~$ 1,01 6 * Transformer tank steel is used in the design optimization software and varies with the efficiency (and size) of each design

. DL3 and DL5 include calculated costs of radiators, which are scaled for each design based on the required cooling surface area.

5.4.3 Material Inputs to the Design Software

– Dry

- Type

Table 5.4

. 4 presents the material prices for a typical dry

- type transformer manufacturer over the five

- year 2006

- 2010 time horizon, indicating the current (2010) , minimum (2006) , and maximum (2008) price s (all in constant 2010$) The highlighted columns are the prices DOE used in the engineering analysis.5

- 49

Table 5.4

. 4 Manufacturer’s Material Prices for Dry

- Type Design Lines

Material Units 2010 Price 2010$ Min.

Price (2006

– 25%) 2010$ Max.

price (2008
+ 25%) 2010$ 20 10 2010$ 200 9 2010$ 200 8 2010$ 200 7 2010$ 200 6 2010$

M36 core steel (26 gauge) $/lb $ 0.66 $

0.46 $

0.84 $ 0.66 $ 0.67 $ 0.67 $ 0.84 $ 0.62 M19 core steel (26 gauge) $/lb $ 0.91 $

0.56 $

1.19 $ 0.91 $ 0.82 $ 0.96 $ 0.95 $ 0.75 M12 core steel $/lb $ 1.03 $ 0.85 $

1.60 $ 1.03 $ 1.09 $ 1.28 $ 1.24 $ 1.13 M6 core steel $/lb $ 1.46 $ 0.94 $

2.19 $ 1.46 $ 1.64 $ 1.75 $ 1.58 $ 1.26 M5 core steel $/lb $ 1.51 $ 0.99 $

2.24 $ 1.51 $ 1.67 $ 1.79 $ 1.61 $ 1.32 M4 core steel $/lb $ 1.59 $

1.03 $ 2.30 $ 1.59 $ 1.70 $ 1.84 $ 1.64 $ 1.38 M3 core steel $/lb $ 1.88 $

1.06 $ 2.60 $ 1.88 $ 1.96 $ 2.08 $ 1.70 $ 1.41 M2 core steel $/lb $ 2.00 $

1.32 $ 2.79 $ 2.00 $ 2.01 $ 2.23 $ 2.18 $ 1.76 H

- 0 DR core steel (laser scribed) $/lb $ 2.06 $

1.41 $ 3.23 $ 2.06 $ 2.38 $ 2.58 $ 2.27 $ 1.89 SA1 (amorphous) finished core, volume production $/lb $ 2.38 $

1.72 $ 3.64 $ 2.38 $ 2.29 $ 2.91 $

- $

- Copper wire, rectangular 0.1 x 0.2, Nomex wrapped $/lb $ 4.52 $

3.07 $

5.53 $ 4.52 $ 3.46 $ 4.42 $ 4.43 $ 4.09 Aluminum wire, rectangular 0.1 x 0.2, Nomex wrapped $/lb $ 2.97 $

2.23 $

3.78 $ 2.97 $ 2.90 $ 3.03 $ 2.98 $ 2.97 Copper strip, thickness range 0.02

- 0.045 $/lb $ 4.97 $

3.41 $

6.09 $ 4.97 $ 3.91 $ 4.87 $ 4.88 $ 4.54 Aluminum strip, thickness range 0.02

- 0.045 $/lb $ 2.08 $

1.56 $ 2.67 $ 2.08 $ 2.01 $ 2.14 $ 2.09 $ 2.08 Nomex insulation $/lb $ 24.50 $

13.72 $ 29.03 $ 24.50 $ 24.73 $ 23.23 $ 20.71 $ 18.29 Cequin insulation $/lb $ 5.53 $

3.84 $

6.09 $ 5.53 $ 5.12 $ 4.87 $ 5.13 $ 5.12 Impregnation $/gal $ 22.55 $

17.16 $ 27.31 $ 22.55 $ 22.71 $ 21.85 $ 22.23 $ 22.88 Winding combs $/lb $ 12.34 $

6.08 $ 15.41 $ 12.34 $ 12.70 $ 12.33 $ 11.99 $

8.10 Enclosure Steel $/lb $ 0.38 $

0.32 $

0.60 $ 0.38 $ 0.39 $ 0.48 $ 0.43 $ 0.43 On the following pages, all the material prices entered into the design software for dry

type distribution transformers are given

. As shown in these tables, DOE marked up the material prices before being entering them into the design software.5

- 50

Table 5.4

. 5 Marked

- up Material Prices for Dry

- Type Units, Current Year (2010) Price

Scenario
Item and Description Units Current 2010 Price 2010$ Scrap & Handling Factory

Overhead Non

Production Software

Input

M36 core steel (26 gauge) $/lb $ 0.66 1.025 1.125 1.25 $ 0.95
M19 core steel (26 gauge) $/lb $ 0.91 1.025 1.125 1.25 $ 1.31
M12 core steel $/lb $ 1.03 1.025 1.125 1.25 $ 1.49
M6 core steel $/lb $ 1.46 1.025 1.125 1.25 $ 2.10
M5 core steel $/lb $ 1.51 1.025 1.125 1.25 $ 2.18
M4 core steel $/lb $ 1.59 1.025 1.125 1.25 $ 2.28
M3 core steel $/lb $ 1.88 1.025 1.125 1.25 $ 2.70
M2 core steel $/lb $ 2.00 1.025 1.125 1.25 $ 2.88
H

- 0 DR core steel (laser scribed) $/lb $ 2.06 1.025 1.125 1.25 $ 2.97 SA1 (amorphous) finished core, volume production $/lb $ 2.38 1.015 1.125 1.25 $ 3.40 Copper wire, rectangular 0.1 x 0.2, Nomex wrapped $/lb $ 4.52 1.025 1.125 1.25 $ 6.52 Aluminum wire, rectangular 0.1 x 0.2, Nomex wrapped $/lb $ 2.97 1.025 1.125 1.25 $ 4.29 Copper strip, thickness range 0.02

- 0.045 $/lb $ 4.97 1.025 1.125 1.25 $ 7.17 Aluminum strip, thickness range 0.02

- 0.045 $/lb $ 2.08 1.025 1.125 1.25 $ 3.00
Nomex insulation $/lb $ 24.50 1.025 1.125 1.25 $ 35.31 Cequin insulation $/lb $ 5.53 1.025 1.125 1.25 $ 7.97 Impregnation $/gal $ 22.55 1.000 1.125 1.25 $ 31.71 Winding combs $/lb $ 12.34 1.025 1.125 1.25 $ 17.79
Enclosure Steel $/lb $ 0.38 1.025 1.125 1.25 $ 0.55

As stated in section 5.3 , the OPS software does not take into account retooling costs associated with changing production designs

. Therefore, to partially capture these differential costs in the design lines that had both buttlap and mitered designs, DOE used adders in DL7 and DL8

. The adders specified an extra 10 cents per pound of core steel for full

- mitered designs

.5

- 51

More detailed costing of the retooling costs for mitering equipment will be covered in the manuf acturer impact analysis (MIA)

. ( S ee Chapter 12

. )
Similar to the liquid

- immersed designs, there are fixed (and some partially variable) hardware costs associated with dry

- type distribution transformers

. These are discussed individually and then summarized in Table 5.4

. 6

. For DL6, a 25 kVA single

- phase, low

- voltage, dry

- type transformer, the low

- voltage and high

- voltage terminal set costs $4

. The mounting frame that attaches the core/coil assembly to the transformer enclosure costs approximately $9.25

. The fiberglass dog

- bone duct

- spacers used for this design line cost $0.24 per foot

. DOE estimated the miscellaneous hardware costs at $4.50

. The ven tilated enclosure

– a 1 6

- gauge steel enclosure, base, and mounting feet

– varies with the size of the core

- coil assembly for the 25kVA unit, and costs approximately $ 50

.
For DL 7 , a 7 5 kVA three

- phase, low

- voltage, dry

- type transformer, the fixed hardware costs are $9 per phase for the high

- voltage terminal board with connection points

. DOE estimated the secondary (low

- voltage) bus

- bar to be seven feet at $1.50 per foot, or $10.50

. The mounting frame that attaches the core/coil assembly to the transformer e nclosure costs approximately $ 19

. The fiberglass dog

- bone duct

- spacers used for this design line cost $0. 32 per foot

. DOE estimated the miscellaneous hardware costs at $ 7

. The ventilated enclosure

– a 14

- gauge steel enclosure, base, and mounting feet

– var ies with the size of the core

- coil assembly for the 7 5kVA unit, and costs approximately $ 90

.
For DL 8 , a 300 kVA three

- phase, low

- voltage, dry

- type transformer, the high

- voltage terminal board costs $27

. DOE estimated the secondary (low

- voltage) bus

- bar to be nine feet at $ 2 .50 per foot, or $ 22 .50

. The mounting frame that attaches the core/coil assembly to the transformer enclosure costs approximately $ 36

. The fiberglass dog

- bone duct

- spacers used for this design line cost $0. 4 2 per foot

. DOE estimated the miscellaneous hardware costs at $ 12

. The ventilated enclosure

– a 14

- gauge steel enclosure, base, and mounting feet

– varies with the size of the core

- coil assembly for the 300 kVA unit, and costs approximately $ 1 00

. For DL9, a 300 kVA three

- phase, medium

- voltage, dry

- type transformer at 45 kV BIL, the low

- voltage and high

- voltage terminal set costs $75

. DOE estimated the secondary (low

voltage) bus

- bar to be eight feet at $10 per foot, or $80

. The mounting frame that attaches the core/coil assembly to the transformer enclosure costs approximately $36

. The fiberglass dog

bone duct

- spacers used for this design line cost $0.42 per foot. DOE estimated the miscellaneous hardware costs at $25

. The ventilated enclosure

– a 14

- gauge steel enclosure, base, and mounting feet

– varies with the size of the core

- coil assembly for the 300 kVA unit, and costs approximately $ 135

. For DL10, a 1500 kVA three

- phase, medium

- voltage, dry

- type transformer at 45 kV BIL, the low

- voltage and high

- voltage terminal set costs $1 20

. DOE estimated the low

- voltage bus

bar to be 14 feet at $10 per foot, or $140

. The mounting frame that attaches the core/coil assembly to the transformer enclosure costs approximately $120

. DOE accounted for the cost of additional bracing in the amorpho us design since the amorphous design uses a wound core rather than a round, cruciform core like the other designs

. This extra bracing is needed for the5

- 52

amorphous design due to the size of DL10 (1500 kVA)

. The weight of the added bracing was calculated as 7 percent of the core and coil weight, and was multiplied by the price for enclosure steel to derive a cost

. The bracing weighs 600 pounds on average and costs approximately $230

. The fiberglass dog

- bone duct

- spacers used for this design line cost $0.52 per foot. DOE estimated the miscellaneous hardware costs at $42

. The ventilated enclosure

– a 1 4

- gauge steel enclosure, base, and mounting feet

– varies with the size of the core

- coil assembly for the 1500 kVA unit, and costs approximately $ 400

. For DL11, a 300 kVA three

- phase, medium

- voltage, dry

- type at 95 kV BIL, the low

voltage and high

- voltage terminal set costs $100

. The high

- voltage terminal boards cost $27

. DOE estimated the low

- voltage bus

- bar is estimated to be 10 feet at $8 per foot, or $80

. The
mo unting frame that attaches the core/coil assembly to the transformer enclosure costs $42

. The fiberglass dog

- bone duct

- spacers used for this design line cost $0.42 per foot. DOE estimated the miscellaneous hardware costs at $32

. The ventilated enclosure

– a 14

- gauge steel enclosure, base, and mounting feet

– varies with the size of the core

- coil assembly for the 300 kVA unit, and costs approximately $ 2 00.
For DL12, a 1500 kVA three

- phase, medium

- voltage, dry

- type at 95 kV BIL, the low

voltage and high

- vol tage terminal set costs $135

. The high

- voltage terminal boards cost $27. DOE estimated the low

- voltage bus

- bar is estimated to be 16 feet at $12 per foot, or $192

. The mounting frame that attaches the core/coil assembly to the transformer enclosure costs $ 125

. DOE accounted for the cost of additional bracing in the amorphous design since the amorphous design uses a wound core rather than a round, cruciform core like the other designs

. This extra bracing is needed for the amorphous design due to the size of DL1 2 (1500 kVA)

. The weight of the added bracing was calculated as 7 percent of the core and coil weight, and was multiplied by the price for enclosure steel to derive a cost

. The added bracing weighs 7 00 pounds on average and costs approximately $2 7 0

. The fiberglass dog

- bone duct

- spacers used for this design line cost $0.56 per foot

. DOE estimated the miscellaneous hardware costs at $54

. The ventilated enclosure

– a 1 4

- gauge steel enclosure, base, and mounting feet

– varies with the size of the
core

- coil a ssembly for the 1500 kVA unit, and costs approximately $ 450

. For DL13 A , a 300 kVA three

- phase, medium

- voltage, dry

- type at 125 kV BIL, the low

voltage and high

- voltage terminal set costs $1 15

. The high

- voltage terminal boards cost $27

. DOE estimated the l ow

- voltage bus

- bar is estimated to be 1 0 feet at $1 0 per foot, or $ 100

. The mounting frame that attaches the core/coil assembly to the transformer enclosure costs $ 50

. The fiberglass dog

- bone duct

- spacers used for this design line cost $0. 42 per foot

. DO E estimated the miscellaneous hardware costs at $ 36

. The ventilated enclosure

– a 1 4

- gauge steel enclosure, base, and mounting feet

– varies with the size of the core

- coil assembly for the 3 00 kVA unit, and costs approximately $ 2 00

. For DL13 B , a 2000 kVA three

- phase, medium

- voltage, dry

- type at 125 kV BIL, the low

voltage and high

- voltage terminal set costs $150

. The high

- voltage terminal boards cost $27

. DOE estimated the low

- voltage bus

- bar is estimated to be 18 feet at $15 per foot, or $270

. The mountin g frame that attaches the core/coil assembly to the transformer enclosure costs $175

. DOE accounted for the cost of additional bracing in the amorphous design since the amorphous design uses a wound core rather than a round, cruciform core like the other d esigns

. This extra5

- 53

bracing is needed for the amorph ous design due to the size of DL 1 3B ( 20 00 kVA). The weight of the added bracing was calculated as 7 percent of the core and coil weight, and was multiplied by the price for enclosure steel to derive a cost

. The added bracing weighs 850 pounds on average and costs approximately $ 330

. The fiberglass dog

- bone duct

- spacers used for this design line cost $0.60 per foot

. DOE estimated the mis cellaneous hardware costs at $60

. The ventilated enclosure

– a 14

- gauge steel enclosure, base, and mounting feet

– varies with the size of the
core

- coil assembly for the 300 kVA un it, and costs approximately $450

.

Table 5.4

. 6 Summary Table of Fixed Material Costs for Dry

- Type Un its Item DL 6 DL 7 DL 8 DL9 DL10 DL11 DL12 DL13 A DL13B LV and HV terminals (set) $4 n/a n/a $75 $120 $100 $135 $1 15 $150 HV terminal board(s) n/a $27 $27 $27 $27 $27 $27 $27 $27 LV bus

- bar n/a $10.50 $22.50 $80 $140 $80 $192 $ 100 $270 Core/coil mounting frame $9.25 $19 $36 $36 $120 $42 $125 $ 50 $175 Additional Bracing n/a n/a n/a n/a ~$ 230 n/a ~$ 270 n/a ~$ 330 Nameplate $0.65 $0.65 $0.65 $0.65 $0.65 $0.65 $0.65 $0.65 $0.65 Dog

- bone duct spacer (ft.) $0.24 $0.32 $0.42 $0.42 $0.52 $0.42 $0.56 $0. 42 $0.60 Winding combs (lb.) n/a n/a n/a n/a n/a $10. 00 $10. 00 $10. 00 $10. 00 Misc. hardware $4.50 $7 $12 $25 $42 $32 $54 $ 36 $60 Enclosure (12, 14 gauge) ~$ 50 ~$ 90 ~$ 100 ~$ 135 ~$ 400 ~$ 200 ~$ 450 ~$ 200 ~$ 450 LV = low voltage HV = high voltage

5.4.4 Labor Costs

Labor costs are a critical aspect of the cost of manufacturing a distribution transformer

. DOE used the same hourly labor cost for both liquid and dry

- type distribution transformers

. It developed the hourly cost of labor using a similar approach to the developme nt of the cost of materials; however, it used different markups

. DOE developed the markups shown in Table 5.4

. 7 after reviewing publicly available information , speaking with transformer manufacturers during 201 1 , and consulting with industry experts familiar with transformer manufacturing in the U.S.5

- 54

Table 5.4

. 7 Labor Markups for Liquid

- Immersed and Dry

- Type Manu facturers Item description Markup percentage Rate per hour Labor cost per hour * $ 16.80 Indirect Production ** 33% $ 22.35 Overhead *** 30% $ 29.05 Fringe † 24% $ 36.03 Assembly Labor Up

- time †† 43% $ 51.52 Fully

- Burdened Cost of Labor 25% $ 64.40 * Cost per hour is from U.S. Census Bureau, 2007 Economic Census

- Detailed Statistics , published October 2009

. Data for NAICS code 3353111 "Power and distribution transformers, except parts" Production workers hours and wages. ** Indirect production labor (e.g., production managers, quality control) as a percent of direct labor on a cost basis

. Navigant Consulting, Inc. (NCI) estimate. *** Overhead includes commissions, dismissal pay, bonuses, vacation, sick leave, and social security contributions

. NCI estimate. † Fringe includes pension contributions, group insurance premiums, workers compensation

. Source: U.S. Census Bureau, 2007 Economic Census

- Detailed Statistics , published October 2009

. Data for NAICS code 3353111 "Power and distribution transformers, except parts" Total fringe benefits as a percent of total compensation for all employees (not just production workers). †† Assembly labor up

- time is a fa ctor applied to account for the time that workers are not assembling units and/or reworking unsatisfactory units

. The markup of 43 percent represents a 70 percent utilization (multiplying by 100/70). NCI estimate.

There are several labor steps involved in manufacturing a liquid

- immersed transformer

. DOE prepared estimates of the amount of labor involved, some varying with the transformer design and others fixed on a per

- unit basis

. These steps are described below, and the amount of time dedicated to each i s given in Table 5.4

. 8

. Cutting, Forming, and Annealing

– This task involves cutting the core steel to lengths on a distributed

- gap core cutting machine, forming the resulting ―donut‖ of core steel into a rectangular shape in a hydraulic press, and then annealing the core in a high temperature annealing furnace

. DOE calculated the labor involved in these activities based on the weight of core (pounds) multiplied by a constant, which varies with the lamination thickness of the core steel

. For DL1, DL2, and DL4, on M6 designs the constant is 0.08, M5 is 0.09, M4 is 0.10, M3 (with or without Lite Carlite) and ZDMH are 0.125, and M2 (with or without Lite Carlite) is 0.16

. For DL3 and DL5, on M6 designs the constant is 0.05, M5 is 0.06, M4 is 0.07, M3 (with or without Lite Carlite) and ZDMH are 0.09, and M2 (with or without Lite Carlite) is 0.11. For the prefabricated core

— SA1 (amorphous material)

— DOE set the labor for cut ting, forming, and annealing to zero.
Primary Winding

– This task entails winding the primary conductor of the transformer

. It includes set

- up time as well as winding time

. The labor hours vary with the number of turns (per phase) for the primary winding

. For DL1, DL2, and DL4, the winding time is 0.0001 hours per turn

. For these smaller kVA ratings (and smaller cores), this rate is very low because some of the larger, liquid

- immersed manufacturers wind multiple coils simultaneously on the same winding mac hine

. This manufacturing approach improves5

- 55

throughput and productivity at the facility

. The rate of 0.0001 hours per turn equates to approximately one

- third of a second per turn

. On DL3 and DL5, due to the larger coil size associated with these units, the winding time is 0.002 hours per turn (approximately 7.2 seconds per turn).
Secondary Winding

– This t ask involves winding the secondary conductor of the transformer

. It includes set

- up time as well as winding time

. On a distribution (step

down) transforme r, the number of secondary turns is always less than the primary

. For the liquid

- immersed units, which are taking a relatively high primary voltage and dropping to below 600V, the turns ratio can be as large as 100:1

. For this reason, the hours per turn of the secondary are considerably higher than the primary, because there are fewer turns over which to amortize the set

- up time as well as a slower winding rate for the secondary, which has larger cross

- sectional area than the primary

. For DL1, DL2, and DL4, the hours per turn of the secondary are 0.015 (54 seconds per turn); for DL3 and DL5, the hours per turn are 0.02 (72 seconds per turn).
Lead Dressing

– Once a wound coil is taken off the winding machine, work must be performed on the leads to prepare th em for the next manufacturing step

. Enamel is removed to enable good electrical connection and insulating tubing is slipped over the cable

. This is a fixed amount of labor, and does not vary with efficiency or design

. Lead dressing time ranges from 0.1 to 1 hour.
Coil Varnishing and Baking

– Once they are complete, the coils are vacuum

- dipped in varnish and baked in an oven to cure the varnish and enhance the integrity of the coil

. This task varies slightly with kVA rating, but does not vary with efficienc y

. The estimated times range from 0.07 to 0.25 hours. Core Assembly (―Lacing‖)

– This task involves assembling and banding the annealed wound core laminations around varnished windings

. The annealed bundle of core steel is disassembled from the inside out by grabbing approximately 1/4 inch bundles, then reassembling the core steel around the coils

. Once all the laminations are reassembled, the core material is clamped to maintain the structure

. The activity involves feeding a banding strip around the core material and using a locking clamp to compress and contain the core material

. The labor rate varies with stack height and lamination thickness for each design

. The average time for core assembly ranges from approximately 0.2 hours (for DL2) to 4.9 hours (f

or DL5).
Tanking and Impregnating

– This task involves inserting and fastening the core/coil assembly into the tank

. Then, a vacuum is pulled and oil is introduced to the tank

. On round tanks, the vacuum and oil step is done through a lid attached to the top of the unit

. On the rectangular and pad

- mounted tanks, the vacuum is pulled in a chamber, which takes a little longer per unit

. Finally, tap changers and bushings are mounted, and bolted connections made

. The time for this activity does not vary with d esign or efficiency, but it does vary by kVA rating and tank shape

. The estimates of labor time for the five liquid

immersed design lines range from 0.1 to 1.8 hours.5

- 56

Inspect ion

– This activity involves verifying that the transformer is assembled properly and is up to a manufacturer's quality specification

. This task includes inspecting the lead dressing, lead tie

- up, and other quality certification specifications

. The time for this activity does not vary with design or efficiency, but it does vary by kVA rating , from 0.05 hours for the smallest units to 0.20 hours for the largest units.
Preliminary Test

– This step involves conducting a test to ensure that the core/coil meets the specified turns ratio, polarity, core loss, etc

. The time for this activity does not vary with design or efficiency, but it does vary by kVA rating from 0.05 to 0.15 hours.

Final Test

– This activity involves testing of the final, assembled unit, with the core/coil assembly immersed in oil

. This test verifies that the unit meets the guaranteed values, including core and coil losses, impedance, and dielectric tests

. The time for this activity does not vary with design or efficiency, but it does vary by kVA rating from 0.1 to 0.25 hours.
Pallet Loading

– This activity involves preparing the transformer for shipping to the customer

. This includes loading the finished transformer onto a pallet, banding the transformer to the pallet, wrapping, and all other necessary steps for shipping

. The time for this activity does not vary with design or efficiency, but it does vary by kVA rating from 0.15 hours for the smallest units to 3 hours for the largest units.
Marking and Miscellaneous

– This task involves preparing any extra markings around the bushings or on the surface of the transfo rmer and other miscellaneous labor associated with preparing the finished transformer for the customer

. The time for this activity does not vary with design or efficiency, but it does vary by kVA rating from 0.08 to 0.35 hours

. Table 5.4

. 8 summarizes the estimates of labor time that DOE used for the five liquid

immersed units.5

- 57

Table 5.4

. 8 Summary of Labor Times for Liquid

- Immersed Units Labor Activity DL1 hrs. DL2

hrs. DL3

hrs. DL4

hrs. DL5

hrs. Cutting, Forming, & Annealing ~1.00 ~0.75 ~4.00 ~3.00 ~8.50 Primary Winding (hrs/turn) 0.0001 0.0001 0.002 0.0001 0.002 Secondary Winding (hrs/turn) 0.015 0.015 0.020 0.015 0.020 Lead Dressing 0.50 0. 1 0.35 0. 75 1.00 Baking Coils 0.10 0.07 0.15 0.17 0.25 Core Assembly ~0. 4 0 ~0. 2 0 ~1. 2 0 ~1.00 ~ 4.9 0 Tanking and Impregnating 0. 30 0.11 0. 65 0. 50 1. 8 0 Inspection 0.10 0.05 0.10 0.15 0.20 Preliminary Test 0.10 0.0 5 0.10 0.10 0.15 Final Test 0.15 0. 1 0.15 0.20 0.25 Pallet Loading 0. 5 0. 15 0.75 0.50 3.00 Marking and Misc. 0. 35 0.0 8 0.35 0.3 5 0.75

Likewise, there are several labor steps involved in manufacturing a dry

- type transformer

. DOE prepared estimates of the amount of labor involved, some varying with the transformer design and others fixed on a per

- unit basis

. These steps are described below, and the amounts o f time dedicated to each are summarized in Table 5.4

. 9

. Core Stacking

– This task involves stacking (assembling) the cut steel laminations into a distribution transformer core

. The amount of labor for this task varies by kVA rating, stack height, and whether the core is grain

- oriented or non

- oriented

. Thus, the labor for core stacking varies with the efficiency of the transformer

. Approximate labor hours for
cor e stacking vary from as little as 0. 25 hours/inch for a 25 kVA single

- phase, low

voltage unit to 0.9 hours/inch for a 2000 kVA, 125kV BIL three

- phase, medium

- voltage unit

. For the prefabricated core

– SA1 (Amorphous material)

– the labor for core stacking (i.e., cutting, forming, and annealing) is set to zero.
Primary Winding

– This task encompasses winding the primary conductor of the transformer

. It includes set

- up time as well as winding time

. The labor hours vary with the number of turns (per phase) for the primary winding , ranging from 0.001 to 0.023 hours/turn.
Secondary Winding

– This task involves winding the secondary conductor of the transformer

. It includes set

- up time as well as winding time

. The winding time of the secondary is considerabl y higher than that of the primary, because there are fewer turns over which to amortize the set

- up time as well as a slower winding rate for the secondary, which has larger cross sectional area

. The hours per turn vary from 0.0 1 to 0.125, depending on the kVA rating (design line).
Lead Dressing

– Once a wound coil is taken off the winding machine, work must be performed on the leads to prepare them for the next manufacturing step

. Enamel is5

- 58

removed to enable good electrical connection and insulating tubing is slipped over the cable

. For a given kVA rating, this is a fixed amount of labor, and does not vary with efficiency or design

. The range is from 0. 15 to 1.0 hours per unit.
Assembly

– This task involves installing the wound co ils onto the partially assembled core, and then lacing the top (yoke) laminations to complete the core

. It also includes setting all the core clamps and completing the core/coil assembly

. DOE assumed the assembly time varies by kVA rating, but does not vary by design within a kV A rating

. For example, DOE estimated the assembly time for a 1500kVA three

- phase unit at six hours, while DOE estimated the assembly time for a 75 kVA three

- phase unit at one hour

. The only exception is for amorphous designs in dry

- type design lines that ar e 1500 kVA or greater

. For DL 10, DL 12, and DL 13 B , DOE used an estimate of sixteen hours for assembly time to account for the added complexity of using an amorphous core in these large designs

. This time estimate is based on time estimates for unpacking (2 hours), unlacing joints (1.5 hours), mounting cores in place (2 hours), re

- lacing core joints (4 hours), setting cores in place (1.5 hours), and attaching the framing and bolting (5 hours).
Inspection

– This activity involves verifying that the transfo rmer is assembled properly and is up to a manufacturer's quality specification

. It includes inspecting the lead dressing, lead tie up, and other quality certification specifications

. The time for this activity does not vary with design or efficiency, but i t does vary by kVA rating. The time estimates vary from 0. 05 hours ( three minutes) for the smaller kVA ratings to 0.25 hours (15 minutes) for the larger units.
Preliminary Test

– This step involves conducting a test to ensure that the core/coil meets the specified turns ratio, polarity, core loss, etc

. The time for this activity does not vary with design or efficiency, but it does vary by kVA rating

. The estimates of labor time range from 0. 05 hours ( three minutes) for the smaller kVA ratings to 0.5 hours (30 minutes) for the larger units.

Final Test

– This activity involves testing the final, assembled unit, with the core/coil assembly immersed in oil

. This test verifies that the unit meets the guaranteed values, including core and coil losses, impedance , and dielectric tests

. The time for this activity does not vary with design or efficiency, but it does vary by kVA rating

. Similar to the preliminary test, the labor time estimates range from 0.1 hours ( six minutes) for the smaller kVA ratings to 0.75 hou rs (45 minutes) for the larger units.
Enclosure Manufacturing

– The labor estimate for this task encompasses all activity associated with the cutting, forming, assembly, priming, painting, and preparation of the enclosure

. This labor estimate varies with the kVA rating, spanning from 0.75 hours for the 25 kVA single

- phase unit up to eight hours for the 1500 and 2000kVA cabinets.
Packing

– This activity involves preparing the transformer for shipping to the customer

. This includes loading the finished trans former onto a pallet, banding the transformer to the pallet, wrapping, and all other necessary steps for shipping

. The time for this activity5

- 59

does not vary with design or efficiency, but it does vary by kVA rating

. The time estimate ranges from 0.20 hours at the low end to 2.0 hours at the higher kVA ratings.
Marking and Miscellaneous

– This task involves preparing any extra markings on the terminal board or on the surface of the transformer, and other miscellaneous labor associated with preparing the finished transformer for the customer

. The time for this activity does not vary with design or efficiency, but it does vary by kVA rating

. The labor estimate ranges from 0. 2 0 hours at the low end to 2.2 hours at the higher kVA ratings.

Table 5.4

. 9 presents the hours of labor needed to complete each step in the manufacturing process for all design lines containing dry

- type transformers.

Table 5.4

. 9 Summary of Labor Times for Dry

- Type Units Labor Activity DL6 hrs. DL7

hrs. DL8

hrs. DL9

hrs. DL10

hrs. DL11

hrs. DL12

hrs. DL13 A

hrs. DL13B

hrs. Core Stacking (hrs/inch) 0.25 0.25

– 0.35 0.38 0.55 0.70 0.70 0.80 0. 7 0 0.90
Primary Winding (hrs/turn) 0.001 0.0015 0.01 0.0 08 0.0 225 0.0 05 0.0125 0.0 05 0.0125 Secondary Winding (hrs/turn) 0.01 0.011 0.040 0.035 0.125 0.035 0. 075 0. 035 0.1 00 Lead Dressing 0.15 0.25 0.50 0.60 1.00 0.60 1.00 0.60 1.00 Assembly , [Amorphous designs] 0.35 1.00 2.50 3.00 6.00 , [16.00] 4.00 6.00 ,

[16.00] 4 .00 6.00 ,

[16.00] Inspection 0.05 0.05 0.10 0.10 0.25 0.10 0.25 0 .1 0.25 Preliminary Test 0.05 0.05 0.10 0.10 0.50 0.15 0.50 0. 15 0.50 Final Test 0.10 0.10 0.15 0.15 0.75 0.25 0.75 0. 25 0.75 Enclosure Manufacturing 0.75 1.50 3.00 5.00 8.00 5.00 8.00 5 .00 8.00 Packing 0.20 0.20 1.00 1.00 2.00 1.00 2.00 1 .00 2.00 Marking and Miscellaneous 0.20 0.20 0.60 0.70 2.20 0.85 2.20 0.85 2.20

5.5 EFFICIENCY LEVELS DOE analyzed designs over a range of efficiency values for each representative unit

. Within the efficiency range, DOE developed designs that approximate a continuous function of efficiency. However, DOE analyzes the incremental impacts of increased efficiency by comparing discrete efficiency benchmarks to a constant baseline efficiency. The baseline efficiency evaluated for each representative unit is the existing standard level efficiency for distribution transformers established in DOE‘s previous rulemaking. The incrementally higher efficien cy levels are meant to characterize the cost

- efficiency relationship above the baseline. These efficiency levels are ultimately used by DOE if it decides to amend the existing energy conservation standards.5

- 60

5.5.1 Criteria for Selecting Efficiency Levels

After t he preliminary analysis, DOE considered several criteria when setting efficiency levels . First, DOE harmonized the efficiency values across single

- phase transformers and the per

- phase kVA equivalent three

- phase transformers. For example, a 50 kVA single

- ph ase transformer would have the same efficiency as a 150 kVA three

- phase transformer. This approach is consistent with DOE‘s methodology from the previous rulemaking. As such, DOE selected equivalent efficiency levels for several of the representative units that have equivalent per

- phase kVA ratings.
Second, DOE selected equally spaced efficiency levels by dividing the entire efficiency range into 5

– 7 evenly spaced increments. The number of increments depended on the size of the efficiency range. This allow ed DOE to examine impacts based on an appropriate resolution of efficiency for each representative unit.
Finally, DOE adjusted the position of some of the equally spaced efficiency levels and examined additional efficiency levels . These minor adjustments to the equally spaced efficiency levels allowed DOE to consider important efficiency values based on the results of the software designs. For example, DOE adjusted some efficiency levels slightly up or down in efficiency to consid er the maximum efficiency potential of non

- amorphous design options. Other efficiency levels were added to consider important benchmark efficiencies, such as the NEMA Premium efficiency for low

- voltage dry

- type distribution transformers. Lastly, DOE consid ered additional efficiency levels to characterize the maximum

- technologically feasible design for representative units where the harmonized per

- phase efficiency value would have been unachievable for one of the representative units

. DOE characterized a max imum

- technologically feasible efficiency level for both standard core technology and symmetric core technology.

5.5.2 Efficiency Levels Selected

Table 5.5

. 1 presents the ef ficiency identified for each efficiency level (EL) in the engineering analysis. Table 5.5

. 2 presents the incremental MSP for each of the least

- costly design options at each efficiency level

.5

- 61

Table 5.5

. 1 Summary of Baselines and Efficiency Levels for Distribution Transformer

Representative Units Des ign Line Representative Unit Base

line E L1 E L2 E L3 E L 4 E L 5 E L 6 E L 7 Eff. [%] Eff. [%] Eff. [%] Eff. [%] Eff. [%] Eff. [%] Eff. [%] Eff. [%]

1 50 kVA, 65 C, single

- phase, 60Hz, 14400V primary, 240/120V secondary, rectangular tank 99.08 99.16 99.22 99.25 99.31 99.42 99.50 99.50

2 25 kVA, 65 C, single

- phase, 60Hz, 14400V primary, 120/240V secondary, round tank 98.91 99.00 99.07 99.11 99.18 99.31 99.41 99.46

3 500 kVA, 65 C, single

- phase, 60Hz, 14400V primary, 277V secondary 99.42 99.48 99.51 99.54 99.57 99.61 99.69 99.73

4 150 kVA, 65 C, three

- phase, 60Hz, 12470Y/7200V primary, 208Y/120V secondary 99.08 99.16 99.22 99.25 99.31 99.42 99.50 99.60

5 1500 kVA, 65 C, three

- phase, 60Hz, 24940GrdY/14400V primary, 480Y/277V secondary 99.42 99.48 99.51 99.54 99.57 99.61 99.69 99.69

6 25 kVA, 150 C, single

- phase, 60Hz, 480V primary, 120/240V secondary, 10kV BIL 98.00 98.23 98.47 98.60 98.80 98.93 99.17 99.44

7 75 kVA, 150 C, three

- phase, 60Hz, 480V primary, 208Y/120V secondary, 10kV BIL 98.00 98.23 98.47 98.60 98.80 98.93 99.17 99.44

8 300 kVA, 150 C, three

- phase, 60Hz, 480V Delta primary, 208Y/120V secondary, 10kV BIL 98.60 98.80 99.02 99.14 99.25 99.32 99.44 99.58

9 300 kVA, 150 C, three

- phase, 60Hz, 4160V Delta primary, 480Y/277V secondary, 45kV BIL 98.82 98.99 99.12 99.28 99.38 99.50 99.59 99.59

10 1500 kVA, 150 C, three

- phase, 60Hz, 4160V primary, 480Y/277V secondary, 45kV BIL 99.22 99.31 99.40 99.50 99.53 99.60 99.67 99.67

11 300 kVA, 150 C, three

- phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL 98.67 98.81 98.94 99.06 99.13 99.32 99.50 99.50

12 1500 kVA, 150 C, three

- phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL 99.12 99.21 99.30 99.39 99.46 99.53 99.59 99.65

13 A 300kVA, 150 ̊C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL 98.63 98.76 98.85 98.92 99.10 99.29 99.48 99.48

13 B 2000kVA, 150 ̊C, three

- phase,

60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL 99.15 99.23 99.31 99.38 99.43 99.49 99.58 99.585

- 62

Table 5.5

. 2 Summary of Incremental Manufacturer Selling Prices Over the Baseline for

Distribution Transformer Representative Units Design Line Representative Unit Base

line E L1 E L2 E L3 E L 4 E L 5 E L 6 E L 7 E L 8
$ $ $ $ $ $ $ $ $

1 50 kVA , 65 C, single

- phase, 60Hz, 14400V primary, 240/120V secondary, rectangular tank - 199 666 811 339 823 1168 N/A N/A

2 25 kVA, 65 C, single

- phase, 60Hz, 14400V primary, 120/240V secondary, round tank - 216 397 215 247 487 708 1185 N/A

3 500 kVA, 65 C, single

- phase, 60Hz, 14400V primary, 277V secondary - 849 935 2481 1606 2131 4139 7002 N/A

4 150 kVA, 65 C, three

- phase, 60Hz, 12470Y/7200V primary, 208Y/120V secondary - 574 1328 2211 1413 1164 1893 4681 N/A

5 1500 kVA, 65 C, three

- phase, 60Hz, 24940GrdY/14400V primary, 480Y/277V secondary - 3472 3881 5886 6585 9350 25704 25704 N/A

6 25 kVA, 150 C, single

- phase, 60Hz, 480V primary, 120/240V secondary, 10kV BIL - 21

- 11

- 8 147 182 321 812 N/A

7 75 kVA, 150 C, three

- phase, 60Hz, 480V primary, 208Y/120V secondary, 10kV BIL - 145 73 241 158 447 641 1704 1704

8 300 kVA, 150 C, three

- phase, 60Hz, 480V Delta primary, 208Y/120V secondary, 10kV BIL - 519 742 904 2113 3862 2325 6734 N/A

9 300 kVA, 150 C, three

- phase, 60Hz, 4160V Delta primary, 480Y/277V secondary, 45kV BIL - 445 656 2,201 2,897 4,238 7,457 N/A N/A

10 1500 kVA, 150 C, three

phase, 60Hz, 4160V primary, 480Y/277V secondary, 45kV BIL - 124 2,840 8,167 10,053 13,554 22,900 N/A N/A

11 300 kVA, 150 C, three

- phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL - 606 2,065 3,001 3,072 4,720 8,307 N/A N/A

12 1500 kVA, 150 C, three

phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL - 2,000 3,587 6,815 12,107 15,458 19,020 28,951 N/A5

- 63

13A 300kVA, 150 ̊C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL - 825 1,329 2,157 4,602 5,898 11,907 N/A N/A

13B 2000kVA, 150 ̊C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL - 1,136 4,553 7,776 11,830 19,143 27,991 N/A N/A

Note: Does not include symmetric core designs

. Based on reference case traditional core designs only.

5.6 RESULTS OF THE ANALY SIS ON EACH DESIGN L INE This section provides a visual representation of the results of the engineering analysis

. The scatter plots in this section show the relationship between the manufacturer‘s selling price and efficiency for each of the 1 4 design lines

. Each dot on the plots represents one unique design created by the software at a given manufacturer‘s selling price and efficiency level

. The placement of each dot (and the uniqueness of each design) is dictated by the design option combinations (core steel and windings), core shape, A/B combination, and the variable design param eters generated by the design software

.

5.6.1 Traditional Core Designs for the Reference Case The designs in this section represent the traditional core designs that DOE analyzed in the life

- cycle cost and national impact analyses

. I n addition to the results p rovided in this section, DOE prepared scatter plots depicting the engineering analysis results for the 14 representative units, including watts of core and coil loss and the weight by efficiency (see Appendix 5A ).
Figure 5.6

. 1 presents a plot of the manufacturer selling prices and efficiency levels for the full database of designs for the representative unit from DL1, a 50kVA single

- phase, liquid

immersed, pad

- mounte d distribution transformer

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:

The current standard efficiency level of 99.08 percent is met by designs using M3 core steel or better. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 99.25 percent , and can reach efficiencies of 99. 5 0 percent.5

- 64 Figure 5.6

. 1 Engineering Analysis Results, Design Line 1
Figure 5.6

. 2 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL2, a 25kVA single

- phase, liquid

immersed, pole

- mount ed distribution transformer

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:
The current standard efficiency level of 98.91 percent is met by designs using M3 core steel or better, though it can be met with M4 or even M5 core steel designs

. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 99.10 percent, and can reac h efficiencies up to 99. 5 percent.5

- 65 Figure 5.6

. 2 Engineering Analysis Results, Design Line 2
Figure 5.6

. 3 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL3, a 500kVA single

- phase, liquid

immersed distribution transformer with radiators

. The efficiency levels shown in this plot
re present transformers at 50 percent of nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:
The current standard efficiency level of 9 9.42 percent is met by designs using M3 core steel or better, though it can be met with some M4 core steel designs

. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 99. 55 percent, and can reach efficiencies above 99. 6 5 percent.5

- 66 Figure 5.6

. 3 Engineering Analysis Results, Design Line 3
Figure 5.6

. 4 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL4, a 150kVA three

- phase, liquid

immersed distribution transformer

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for tempera ture

. The following observations can be made about this scatter plot:
The current standard efficiency level of 99.08 percent is met by designs using M3 core steel or better. The amorphous metal (SA1) core is the most cost

- effective design for any efficien cy level above 99. 25 percent, but amorphous designs have a minimum efficiency of 99.27 percent. The amorphous designs can reach efficiencies up to 99.60 percent.5

- 67 Figure 5.6

. 4 Engineering Analysis Results, Design Line 4
Figure 5.6

. 5 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL5, a 1500kVA three

- phase, liquid

immersed distributi on transformer

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:
The current standard efficiency level of 99.42 percent is met by designs using M3 core steel or better, though it can be met with some M4 core steel designs. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 99

. 5 0 percent, and can reach efficiencies up to 99. 7 percent.5

- 68 Figure 5.6

. 5 Engineering Analysis Results, Design Line 5
Figure 5.6

. 6 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL 6 , a 25 kVA single

- phase, low

voltage , dry

- type distribution transformer

. The efficiency levels shown in this plot represent transformers at 35 percent of nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:
The current standard efficiency level of 9 8.00 percent is met by designs using M 6 core steel or better. The NEMA Premium efficiency level of 98.60 percent is met by designs using M4 core steel or better. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 9 8

. 8 0 percent, and can reach efficiencies up to 99. 40 percent.5

- 69 Figure 5.6

. 6 Engineering Analysis Results, Design Line 6
Figure 5.6

. 7 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL 7 , a 7 5kVA three

- phase, low

- voltage , dry

- type distribution transformer

. The efficiency levels shown in this plot represent transformers at 3 5 percent of nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:
The current standard efficiency level of 98.00 percent is met by designs using M12 core steel or better. The NEMA Premium effici ency level of 98.60 percent is met by designs using M6 core steel or better. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 98.9 3 percent, and can reach efficiencies up to 99.40 percent.5

- 70 Figure 5.6

. 7 Engineering Analysis Results, Design Line 7
Figure 5.6

. 8 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL 8 , a 300 kVA three

- phase, low

voltage , dry

- type distribution transformer

. The efficiency levels shown in this plot re present transformers at 35 percent of nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:
The current standard efficiency level of 98.60 percent is met by designs using M6 core steel or better. The NEMA Premium efficiency level of 99.02 percent is met by designs using M3 core steel or better. The amorphous metal (SA1) core is the only design that can achieve an efficiency of 99.40 percent or greater, and can reach efficiencies up to 99.60 percen t.5

- 71 Figure 5.6

. 8 Engineering Analysis Results, Design Line 8
Figure 5.6

. 9 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL9, a 300kVA three

- phase, medium

voltage, dry

- type transformer with a 45kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent o f nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:
The current standard efficiency level of 98.82 percent is met by designs using M6 core steel or better. The five

- legged amorphous metal (SA 1) core is the most cost

- effective design for any efficiency level above 9 9

. 20 percent, and can reach efficiencies up to 99. 59 percent.5

- 72 Figure 5.6

. 9 Engineering Analysis Results, Design Line 9
Figure 5.6

. 10 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL10, a 1500kVA three

- phase, medium

voltage, dry

- type transformer with a 45kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:
The current standard efficiency level of 99.22 percent is met by designs using M5 core steel or better. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 99.40 percent, and can reach efficiencies up to 9 9. 67 percent.5

- 73 Figure 5.6

. 10 Engineering Analysis Results, Design Line 10
Figure 5.6

. 11 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL11, a 300kVA three

- phase, medium

voltage, dry

- type t ransformer with a 95kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load

. The following observations can be made about this scatter plot:
The current standard efficiency level of 98.67 percent is met by d esigns using M4 core steel or better. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 99. 00 percent, and can reach efficiencies up to 99. 5 0 percent.5

- 74 Figure 5.6

. 11 Engineering Analysis Results, Design Line 11
Figure 5.6

. 12 presents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL12, a 1500kVA three

- phase, medium

voltage, dry

- type transformer with a 95kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load

. The following observations can be made about this scatter plot:
The current standard efficiency level of 99.12 percent is met by designs using M5 core steel or better. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 99.40 percent, and can reach efficiencies above 99.65 percent.5

- 75 Figure 5.6

. 12 Engineering Analysis Results, Design Line 12
Figure 5.6

. 13 presents a plot of the manufacturer sales prices and efficiency levels for the full database of des igns for the representative unit from DL13 A , a 300kVA three

- phase, medium

- voltage, dry

- type transformer with a 125kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:
The current standard efficiency level of 9 8.63 percent is met by designs using M 4 core steel or better. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 99. 10 percent, and can reach efficiencies up to 99. 48 percent.5

- 76 Figure 5.6

. 13 Engineering Analysis Results, Design Line 13 A
Figure 5.6

. 14 resents a plot of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL13 B , a 20 00kVA three

- phase, medium

- voltage, dry

- type transformer with a 125kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The following observations can be made about this scatter plot:

The current standard efficienc y level of 99.15 pe rcent is met by designs using M5 core steel or better. The amorphous metal (SA1) core is the most cost

- effective design for any efficiency level above 99.43 percent, and c an reach efficiencies up to 99.5 8 percent.5

- 77 Figure 5.6

. 14 Engineering Analy sis Results, Design Line 13B

5.6.2 Symmetric Core Designs for the Reference Case The designs in this section represent the symmetric core designs that DOE analyzed in the life

- cycle cost and national impact analyses during the preliminary analysis

. As mentioned in section 5.3.3.2 , DOE simulated symmetric core designs by adjusting design parameters from each of its traditional core designs in the reference case

. This section presents graphs showing the traditional core designs and the symmetric core designs

. Since the symmetric core designs yielded greater efficiencies than the original, traditional core designs , DOE considered an additional efficiency level fo r the max

- tech efficiency level.
Figure 5.6

. 15 presents a plot of the manufacturer sales prices and efficiency levels for the simulated symmetric core designs compared to the traditional core designs for the representative uni t from DL 4 , a 150 kVA three

- phase, liquid

- immersed transformer

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. These symmetric core designs do not account for a tertiary win ding, but rather analyze the cost

- efficiency relationship of symmetric cores for the subgroup of distribution5

- 78

transformers that would not require a tertiary winding

. The maximum efficiency achievable using a symmetric core design is 99.65 percent, represen ted by efficiency level 7.

Figure 5.6

. 15 Symmetric Core Engineering Analysis Results, Design Line 4
Figure 5.6

. 16 presents a plot of the manufacturer sales prices and efficiency levels for the simulated symmetric core designs compared to the traditional core designs for the representative unit from DL 5 , a 150 0 kVA three

- phase, liquid

- immersed transformer

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. These symmetric core designs do not account for a tertiary winding, but r ather analyze the cost

- efficiency relationship of symmetric cores for the subgroup of distribution transformers that would not require a tertiary winding

. The maximum efficiency achievable using a symmetric core design is 99. 7 5 percent, represented by effi ciency level 7.5

- 79

Figure 5.6

. 16 Symmetric Core Engineering Analysis Results, Design Line 5
Figure 5.6

. 17 presents a plot of the manufacturer sales prices and efficiency levels for the simulated symmetric core designs compared to the traditional core designs for the representative unit from DL 7 , a 75 kVA three

- phase, low

- voltage, dry

- type distribution transformer

. The efficiency levels shown in this plot represent transformers at 35 percent of nameplate load and are corrected for temperature

. The maximum efficiency achievable using a symmetric core design is 99. 4 8 percent, represented by efficiency level 8

.5

- 80

Figure 5.6

. 17 Symmetric Core Engineering Analysis Results, Design Line 7
Figure 5.6

. 18 presents a plot of the manufacturer sal es prices and efficiency levels for the simulated symmetric core designs compared to the traditional core designs for the representative unit from DL 8 , a 300 kVA three

- phase, low

- voltage, dry

- type distribution transformer

. The efficiency levels shown in thi s plot represent transformers at 35 percent of nameplate load and are corrected for temperature

. The maximum efficiency achievable using a symmetric core design is 99. 63 percent, represented by efficiency level 6

.5

- 81

Figure 5.6

. 18 Symmetric Core Engineering Analysis Results, Design Line 8
Figure 5.6

. 19 presents a plot of the manufacturer sales prices and efficiency levels for the simulated symmetric core designs compared to the traditional core designs for the representative unit from DL 9 , a 300kVA three

- phase, medium

- voltage, dry

- type distribution transformer with a 45kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The maximum efficiency achievable us ing a symmetric core design is 99.6 2 percent, represented by efficiency level 6.5

- 82

Figure 5.6

. 19 Symmetric Core Engineering Analysis Results, Design Line 9
Figure 5.6

. 20 presents a plot of the manufacturer sales prices and efficiency levels for the simulated symmetric core designs compared to the traditional core designs for the representative unit from DL 10 , a 15 00kVA three

- phase, medium

- voltage, dry

- type distribution transformer with a 45kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The maximum efficiency achievable using a sy mmetric core design is 99. 71 percent, represented by efficiency level 6.5

- 83

Figure 5.6

. 20 Symmetric Core Engineering Analysis Results, Design Line 10
Figure 5.6

. 21 presents a plot of the manufacturer sales prices and efficiency levels for the simulated symmetric core designs compared to the traditional core designs for the representative unit from DL1 1 , a 3 00kVA three

- phase, medium

- voltage, dry

- type distribution transformer with
a 9 5kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The maximum efficiency achievable u sing a symmetric core design is 99. 55 percent, represented by efficiency level 6.5

- 84

Figure 5.6

. 21 Symmetric Core Engineering Analysis Results, Design Line 11
Figure 5.6

. 22 presents a plot of the manufacturer sales prices and efficiency levels for the simulated symmetric core designs compared to the traditional core designs for the representative unit from DL1 2 , a 15 00k VA three

- phase, medium

- voltage, dry

- type distribution transformer with a 95kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The maximum efficiency achievable using a symmetric core design is 99. 69 percent, represented by efficiency level 7

.5

- 85

Figure 5.6

. 22 Symmetric Core Engineering Analysis Results, Design Line 12
Figure 5.6

. 23 presents a plot of the manufacturer sales prices and efficiency levels for the simulated symmetric core designs compared to the traditional core designs for the representative unit from DL1 3 B , a 20 00kVA thre e

- phase, medium

- voltage, dry

- type distribution transformer with a 12 5kV BIL

. The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature

. The maximum efficiency achievable using a symmet ric core design is 99.69 percent, represented by efficiency level 6

.5

- 86

Figure 5.6

. 23 Symmetric Core Engineering Analysis Results, Design Line 13 B

5.7 THREE EXAMPLE TRANSF ORMER DESIGNS AND CO ST BREAKDOWNS

This section presents some of the OPS transformer designs from DOE‘s Engineering Analysis database

. As discussed earlier, to prepare a cost

- efficiency relationship on selected representative units, DOE contracted Optimized Program Service (OPS), a software comp any specializing in transformer design since 1969

. Using a range of input parameters and material prices, more than 39, 000 transformer designs were created by OPS for DOE‘s analysis

. For each design, the software generates specific information about the co re and coil, including physical characteristics, dimensions, material requirements and mechanical clearances, as well as a complete electrical analysis of the final design

. For information on OPS and their software, visit their website: http://www.opsprograms.com/home.html

. To illustrate the typical output from the OPS software, a design from each of the three superclasses ( i.e. , liquid

- immersed, low

- voltage dry

- type and medium

- voltage dry

- type) are presen ted in this section

. As these practical designs illustrate, the software output is used to create a bill of materials, which is marked

- up to arrive at the manufacturer‘s selling price

. The OPS software provides an electrical analysis including efficiency, which, when plotted with the manufacturer‘s selling price, constitutes the primary output of the engineering analysis.
The three distribution transformers presented are from three design lines : 1, 7, and 12

. Across all the design lines, the complete datab ase of designs contains 39,618 distribution transformer specification and winding sheets, bills of materials, and performance reports

. Any5

- 87

infeasible designs or designs below the minimum efficiency standard are removed and then t his design database is u sed by the LCC analysis (see Chapter 8) as it simulates purchases of distribution transformers in the marketplace.

Design Line 1 : 50 kVA single

- phase, liquid

- immersed

. M 2 core steel with copper primary and aluminum secondary windings (M 2Cu Al) at a $ 3 .00 A an d a $ 1

. 2 0 B evaluation formula.
Design Line 7 : 75 kVA three

- phase, low

- voltage dry

- type

. M6 full

- mitered core steel with aluminum primary and secondary windings (M6AlAl) at a $0. 5 0 A and a $0. 1 0 B evaluation formula.
Design Line 12 : 1500 kVA three

- phase, medium

- voltage dry

- type

. M 3 step

- lap core steel with aluminum primary and secondary windings (M 3Al Al) at a $ 1

. 5 0 A and a $0. 3 0 B evaluation formula.
For the three designs presented, the design detail report is followed by a bill of materials showing the cost calculation, and a pie chart providing a breakdown of the final selling price.

5.7.1 Design Details Report for Transformer from Design Line 1 A design specification report for a 50kVA single

- phase liquid

- immersed transformer appears below

. Thi s design incorporates M 2 core steel, with a copper primary and an aluminum secondary

. The evaluation factors for this design are $ 3 .00 A and $ 1

. 2 0 B

. The bill of materials and associated breakdown of costs for this design are also reported, after the desig n and electrical analysis reports.5

- 885

- 89

Table 5.7

. 1 provides the bill of materials which was calculated from the OPS design details report

. This bill of materials uses the raw material prices given in this chapter for fixed and variable materi als used in building the transformer

. These materials are then marked

- up at5

- 90

the bottom of the table to arrive at the manufacturer‘s selling price

. This table provides the bill of materials for a transformer from design line 1, a 50kVA single

- phase, liquid

- immersed, pad

mount M 2 design, with a copper primary and an aluminum secondary

. This design was generated using a $ 3 .00A and $ 1

. 2 0B.

Table 5.7

. 1 Bill of Materials for Transformer from Design Line 15

- 91

* Indica tes those items to which the scrap factor (1.0%) and the handling and slitting factor (1.5% are applied. ** Price based on rounded estimations

. The non

- rounded price may vary slightly. Figure 5.7

. 1 provides a summary of the costs contributing to the total selling price of the transformer from design line 1

. For this design, approximately 5 7 percent of the final manufacturer selling pric e is direct material and scrap

. Labor accounts for 9 percent of the price, factory overhe ad accounts for 7 percent, and together, shipping and non

- production costs account for 2 7 percent.

Figure 5.7

. 1 Manufacturer Selling Price Breakdown, Transformer from Design Line 1

5.7.2 Design Details Report for Transformer from Design Line 7 The following design report provides information on one of the several designs prepared to study the representative unit from d esign line 7

. This is a 75kVA, three

- phase, low

- voltage, dry

- type unit

. The design shown here (out of the 39,618 designs in the database) is for M6 full

mitered core steel with aluminum primary and secondary windings, and a $0. 50 A and $0. 1 0B. Core/Coils 44%

Non

- Production 18% Shipping 9% Factory Overhead 7% Labor

9% Other Material

13%5

- 925

- 93

Table 5.7

. 2 provides the bill of materials which was calculated from the OPS design details report

. This bill of materials uses the raw material prices given in this chapt er for fixed and variable materials used in building the transformer

. These materials are then marked

- up at the bottom of the table to arrive at the manufacturer‘s selling price

. This table provides the bill of materials for a transformer from design line 7, a 75kVA three

- phase, low

- voltage, dry

- type M6 design, with an aluminum primary and an aluminum secondary

. This design uses a butt

- lap core configuration, and was generated using a $0. 5 0A and $0. 1 0B.5

- 94

Table 5.7

. 2 Bill of Materials for Transformer from Design Line 75

- 95

* Indicates those items to which the scrap factor (1.0%) and the handling and slitting factor (1.5% are applied. ** Price based on rounded estimations

. The non

- rounded price may vary slightly. Figure 5.7

. 2 provides a summary of the costs contributing to the total selling price of the transformer from design line 7

. For this design, approximately 50 percent of the final manufacturer selling price is direct material and scrap

. Labor accounts for 18 percent of the price, factory overhead accounts for 6 percent, and together, shipping and non

- production costs account for 26 percent.

Figure 5.7

. 2 Manufacturer Selling Price Breakdown, Transformer from Design Line 7

5.7.3 Design Details Report for Transformer from Design Line 12 The following design report provides information on one of several designs prepared to study the representative unit from design line 12

. This is a 1500kVA, three

- phase, medium

voltage, dry

- type unit at 95kV BIL

. The design shown here (out of the 39,618 designs in the database) is for M3 step

- lap mitered core steel with aluminum primary and secon dary windings, and a $1.50A and $0.30B

. This is a different design option combination than the original design selected for the preliminary analysis, which was for M 4 core steel with copper primary and aluminum secondary windings, and a $ 1

. 5 0A and $0. 3 0B. Core/Coils 36%

Non

- Production 19% Shipping 7% Factory Overhead 6% Labor 18% Other Material

14%5

- 965

- 975

- 98

Table 5.7

. 3 provides the bill of materials which was calculated from the OPS design details report

. This bill of materials uses the raw material prices given in this chapter for fixed and variable materials used in building the transformer

. These materials are then marked

- up at the bottom of the table to arrive at the manufacturer‘s selling price

. This table provides the bill of materials for a transform er from design line 12, a 1500kVA three

- phase, medium

- voltage, dry

type design with M 3 step

- lap mitered core steel and aluminum primary and secondary windings

. This design was generated using a $ 1

. 5 0A and $0. 3 0B.5

- 99

Table 5.7

. 3 Bill of Materials for Transformer from Design Line 12

* Indicates those items to which the scrap factor (1.0%) and the handling and slitting factor (1.5% are applied.
** Additional sc r ap on core due to mitering process.
*** Price based on rounded estimations

. The non

- rounded price may vary slightly. Figure 5.7

. 3 provides a summary of the costs contributing to the total selling price o f the transformer from design line 12

. For this design, approximately 59 percent of the final5

- 100

manufacturer selling price is direct material and scrap

. Labor accounts for 9 percent of the price, factory overhead accounts for 7 percent, and together, shippin g and non

- production costs account for 25 percent.

Figure 5.7

. 3 Manufacturer Selling Price Breakdown, Transformer from Design Line 12 Core/Coils 35%

Non

- Production 19% Shipping 6% Factory Overhead 7% Labor 9% Other Material 24%