5-i CHAPTER 5. ENGINEERING ANALYSIS

TABLE OF CONTENTS

5.1 INTRODUCTION ............................................................................................... 5-1 5.2 STRUCTURING THE ENGINEERING 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 INPUTS FOR SOFTWARE MOD EL ........................ 5-14 5.3.1 A and B Loss Valuation Inputs .............................................................. 5-15 5.3.2 Core Material Options ............................................................................ 5-17 5.3.3 Core Configurations ............................................................................... 5-18 5.3.3.1 Standard Core Configurations .................................................... 5-19 5.3.3.2 Symmetric Core Configurations ................................................ 5-21 5.3.4 Less

- Flammable Liquid

- Immersed Transformers ................................. 5-22 5.3.5 Design Line 1 Representative Unit ........................................................ 5-22 5.3.6 Design Line 2 Representative Unit ........................................................ 5-23 5.3.7 Design Line 3 Representative Unit ........................................................ 5-24 5.3.8 Design Line 4 Representative Unit ........................................................ 5-25 5.3.9 Design Line 5 Representative Unit ........................................................ 5-26 5.3.10 Design Line 6 Representative Unit ........................................................ 5-27 5.3.11 Design Line 7 Representative Unit ........................................................ 5-28 5.3.12 Design Line 8 Representative Unit ........................................................ 5-30 5.3.13 Design Line 9 Representative Unit ........................................................ 5-31 5.3.14 Design Line 10 Representative Unit ...................................................... 5-32 5.3.15 Design Line 11 Representative Unit ...................................................... 5-33 5.3.16 Design Line 12 Representative Unit ...................................................... 5-34 5.3.17 Design Line 13A Representative Unit ................................................... 5-35 5.3.18 Design Line 13B Representative Unit ................................................... 5-36 5.3.19 Newly Optimized Designs and Previously Optimized Designs ............ 5-37 5.4 MATERIAL AND LABOR I NPUTS ................................................................ 5-37 5.4.1 Material Prices ....................................................................................... 5-39 5.4.2 Material Price Inputs to the Design Software – Liquid- Immersed ........ 5-41 5.4.3 Material Price Inputs to the Design Software – Dry

- Type .................... 5-44 5.4.4 Labor Costs ............................................................................................ 5-48 5.4.4.1 Liquid- Immersed Labor Hours .................................................. 5-49 5.4.4.2 Dry -Type Labor Hours .............................................................. 5-52 5.5 EFFICIENCY LEVELS ..................................................................................... 5-54 5.5.1 Criteria for Developing Efficiency Levels ............................................. 5-54 5.5.2 Efficiency Levels Selected ..................................................................... 5-54 5.5.3 BusLead and Bus Loss Correction ......................................................... 5-58 5.6 RESULTS OF THE ANALYSIS ON EACH DESIGN L INE .......................... 5-58 5.6.1 Traditional Core Designs for the Reference Case .................................. 5-58 5.6.2 Symmetric Core Designs ....................................................................... 5-86 5.7 THREE EXAMPLE DESIGNS AND COST BREAKDOWN S ....................... 5-865- ii 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 ................. 5-91 5.7.3 Design Details Report for Transformer from Design Line 12 ............... 5-95

LIST OF TABLES

Table 5.1 Equipment Classes and Number of kVA Ratings ........................................... 5-2 Table 5.2 Engineering Design Lines (DLs) and Representative Units for Analysis ...... 5-3 Table 5.3 Liquid- Immersed Design Lines and Representative Units ............................. 5-8 Table 5.4 Dry- Type, Low

- Voltage Design Lines and Representative Units .................. 5-9 Table 5.5 Dry-Type, Medium- Voltage, Three

- Phase Design Lines ............................. 5-10 Table 5.6 Common Scaling Relationships in Transformers ......................................... 5-11 Table 5.7 Scaling Exponents By Equipment Class ....................................................... 5-13 Table 5.8 A and B Grid Combinations Used by Software to Generate Design Database 5- 16 Table 5.9 A and B Fan Com binations Used by Software to Generate Design Database . 5- 16 Table 5.10 Core Steel Grades, Thicknesses and Associated Losses ............................. 5-18 Table 5.11 Core Configurations Used in Each Design Line ......................................... 5-19 Table 5.12 Design Option Combinations for the Design Line 1 Representative Unit . 5-23 Table 5.13 Design Option Combinations for the Design Line 2 Representative Unit . 5-24 Table 5.14 Design Option Combinations for the Design Line 3 Representative Unit . 5-25 Table 5.15 Design Option Combinations for the Design Line 4 Representative Unit . 5-26 Table 5.16 Design Option Combinations for the Design Line 5 Representative Unit . 5-27 Table 5.17 Design Option Combinations for the Design Line 6 Representative Unit . 5-28 Table 5.18 Design Option Combinations for the Design Line 7 Representative Unit . 5-29 Table 5.19 Limits on Flux Density for Design Line 7 Representative Unit ................. 5-30 Table 5.20 Design Option Combinations for the Design Line 8 Representative Unit . 5-31 Table 5.21 Design Option Combinations for the Design Line 9 Representative Unit . 5-32 Table 5.22 Design Option Combinations for the Design Line 10 Representative Unit 5-33 Table 5.23 Design Option Combinations for the Design Line 11 Representative Unit 5-34 Table 5.24 Design Option Combinations f or the Design Line 12 Representative Unit 5-35 Table 5.25 Design Option Combinations for the Design Line 13A Representative Unit . 5- 36 Table 5.26 Typical Manufacturer’s Material Prices for Liquid

- Immersed Design Lines 5- 42 Table 5.27 Summary Table of Fixed Material Costs for Liquid- Immersed Units ........ 5-43 Table 5.28 Manufacturer’s Material Prices for Dry

- Type Design Lines ...................... 5-44 Table 5.29 Summary Table of Fixed Material Costs for Dry- Type Units .................... 5-48 Table 5.30 Labor Markups for Liquid- Immersed and Dry

- Type Manufacturers ......... 5-49 Table 5.31 Summary of Labor Times for Liquid- Immersed Units ............................... 5-52 Table 5.32 Summary of Baselines and Efficiency Levels for Distribution Transformer Representative Units ................................................................................... 5-55 Table 5.33 Summary of 2010 Incremental Manufacturer Selling Prices Over the Baseline for Distribution Transformer Representative Units .................................... 5-565- iii Table 5.34 Summary of 2011 Incremental Manufacturer Selling Prices Over the Baseline for Distribution Transformer Representative Units .................................... 5-57 Table 5.35 Bill of Materials for Transformer from Design Line 1 ............................... 5-90 Table 5.36 Bill of Materials fo r Transformer from Design Line 7 ............................... 5-94 Table 5.37 Bill of Materials for Transformer from Design Line 12 ............................. 5-99

LIST OF FIGURES

Figure 5.2.1 Efficiency Levels within an Equipment Class (Logarithmic) ................... 5-12 Figure 5.3.1 A and B Combination Software Inputs Used in the Engineering Analysis .. 5- 17 Figure 5.3.2 Graphic of Single-Phase Core Configurations ......................................... 5-20 Figure 5.3.3 Gr aphic of Three -phase Core Configurations .......................................... 5-20 Figure 5.3.4 Cruciform Core Cross- Section ................................................................. 5-21 Figure 5.4.1 Method of Cost Account for Distribution Transformers Rulemaking ...... 5-38 Figure 5.6.1 Engineering Analysis Results, Design Line 1, 2011 ................................ 5-59 Figure 5.6.2 Engineering Analysis Results, Design Line 1, 2010 ................................. 5-60 Figure 5.6.3 Engineering Analysis Results, Design Line 2, 2011 ................................ 5-61 Figure 5.6.4 Engineering Analysis Results, Design Line 2, 2010 ................................. 5-62 Figure 5.6.5 Engineering Analysis Results, Design Line 3, 2011 ................................ 5-63 Figure 5.6.6 Engineering Analysis Results, Design Line 3, 2010 ................................. 5-64 Figure 5.6.7 Engineering Analysis Results, Design Line 4, 2011 ................................ 5-65 Figure 5.6.8 Engineering Analysis Results, Design Line 4, 2010 ................................. 5-66 Figure 5.6.9 Engineering Analysis Results, Design Line 5, 2011 ................................ 5-67 Figure 5.6.10 Engineering Analysis Results, Design Line 5, 2010 ............................... 5-68 Figure 5.6.11 Engineering Analysis Results, Design Line 6, 2011 .............................. 5-69 Figure 5.6.12 Engineering Analysis Results, Design Line 6, 2010 ............................... 5-70 Figure 5.6.13 Engineering Analysis Results, Design Line 7, 2011 .............................. 5-71 Figure 5.6.14 Engineering Analysis Results, Design Line 7, 2010 ............................... 5-72 Figure 5.6.15 Engineering Analysis Results, Design Line 8, 2011 .............................. 5-73 Figure 5.6.16 Engineering Analysis Results, Design Line 8, 2010 ............................... 5-74 Figure 5.6.17 Engineering Analysis Results, Design Line 9, 2011 .............................. 5-75 Figure 5.6.18 Engineering Analysis Results, Design Line 9, 2010 ............................... 5-76 Figure 5.6.19 Engineering Analysis Results, Design Line 10, 2011 ............................ 5-77 Figure 5.6.20 Engineering Analysis Results, Design Line 10, 2010 ............................. 5-78 Figure 5.6.21 Engineering Analysis Results, Design Line 11, 2011 ............................ 5-79 Figure 5.6.22 Engineering Analysis Results, Design Line 11, 2010 ............................. 5-80 Figure 5.6.23 Engineering Analysis Results, Design Line 12, 2011 ............................ 5-81 Figure 5.6.24 Engineering Analysis Results, Design Line 12, 2010 ............................. 5-82 Figure 5.6.25 Engineering Analysis Results, Design Line 13A, 2011 ......................... 5-83 Figure 5.6.26 Engineering Analysis Results, Design Line 13A, 2010 .......................... 5-84 Figure 5.6.27 Engineering Analysis Results, Design Line 13B, 2011 ......................... 5-85 Figure 5.6.28 Engineering Analysis Results, Design Line 13B, 2010 .......................... 5-86 Figure 5.7.1 Manufacturer Selling Price Breakdown, Transformer from Design Line 1 . 5- 915- iv 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 for 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 (MSP) of a transformer and its corresponding efficiency rating. This relationship serves as the basis for the subsequent cost-benefit calculations for individual customer s, manufacturers, and the nation (see chapter 8, Life- Cyc le Cost and Payback Period Analyses).

5.2 STRUCTURING THE ENGI NEERING ANALYSIS

As discussed in the market and technology assessment ( chapter 3), distribution transformers are classified by their insulation type (liquid -immersed or dry-type), the number of phas es (single or three), the primary voltage (low-voltage or medium-voltage for dry- types) and the basic impulse insulation level (BIL) rating (for medium- voltage dry

- type)

. Following this convention, the U.S. Department of Energy (DOE) developed ten equipmen t classes, shown in Table 5.1

. These equipment classes were adapted from the National Electrical Manufacturers Association (NEMA)’s TP 1 classification system, althoug h they do not follow the classification system precisely

. 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 increa se the differentiation of medium-voltage, dry- type transformers, 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 di stribution 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 -2002, 1

Table 5.1 there are 99 kVA ratings across all the equipment classes . For DOE’s rulemaking,because of the greater degree of differentiation around the BIL rating in medium-voltage, drytype transformers, there are 115 kVA ratings across all the equipment classes, as shown in

.

1 NEMA’s TP 1

- 2002 can be found online at: http://www.nema.org/Products/Pages/Transformers.aspx

.5-2 Table 5.1 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 on all 115 kVA ratings, so it sought to develop an approach that simplified the analysis while retaining reasonable 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 construction methods. Thus, DOE simplified the analysis by creating 1 4 engineering design lines, which group kVA ratings based on similar principles of design and construction. The 1 4 design lines subdivide the equipment classes, to improve the accuracy 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 different BIL ratings ).

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 14. 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). DOE used kVA scaling to extrapolate findings from a representative unit to the other kVA ratings within its design line. . An example of how DOE applied this scaling appear s in section 5.2.1 of this chapter. A technical discussion of the derivation of kVA scaling appears in appendix 5B.

Table 5.2 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 selection of the representative units follow Table 5.2

.5-3 Table 5.2 Engineering Design Lines (DLs) and Representative Units for Analysis

DL Type of Distribution Transformer kVA Range Representative Unit for this Engineering Design Line

1 Liquid- immersed, single

phase, rectangular tank 10–833 50 kVA, 65 **°** C, single

- phase, 60Hz, 14400V primary, 240/120V secondary, rectangular tank, 95kV BIL

2 Liquid- immersed, single

phase, round tank 10–833 25 kVA, 65 **°** C, single-phase, 60Hz, 14400V primary, 120/240V secondary, round tank, 125 kV BIL

3 Liquid

- immersed, single

phase 10–833 500 kVA, 65 **°** C, single-phase, 60Hz, 14400V primary, 277V secondary, 150kV BIL

4 Liquid- immersed, three

phase 15–2500 150 kVA, 65 **°** C, three

- phase, 60Hz, 12470Y/7200V primary, 208Y/120V secondary, 95kV BIL

5 Liquid- immersed, three

phase 15–2500 1500 kVA, 65 **°** C, three-phase, 60Hz, 24940GrdY/14400V primary, 480Y/277V secondary, 125 kV BIL

6 Dry -type, low-voltage, single

- phase 15–333 25 kVA, 150 **°** C, single-phase, 60Hz, 480V primary, 120/240V secondary, 10kV BIL

7 Dry

- type, low

- v oltage, three

- phase 15–1000 75 kVA, 150 **°** C, three-phase, 60Hz, 480V primary, 208Y/120V secondary, 10kV BIL

8 Dry -type, low-voltage, three

- phase 15–1000 300 kVA, 150 **°** C, three-phase, 60Hz, 480V Delta primary, 208Y/120V secondary, 10kV BIL

9 Dry

- type , medium

voltage, three-phase, 20- 45kV BIL 15–2500 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 15–2500 1500 kVA, 150 **°** C, three-phase, 60Hz, 4160V primary, 480Y/277V secondary, 45kV BIL

11 Dry

- type, medium

voltage, three-phase, 46- 95kV BIL 15–2500 300 kVA, 150 **°** C, three-phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL

12 Dry

- type, medium

voltage, three-phase, 46- 95kV BIL 15–2500 1500 kVA, 150 **°** C, three

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

13A 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

13B Dry -type, mediumvoltage, three-phase, 96- 150kV BIL 225– 2500 2000 kVA, 150 **°** C, three -phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL5-4 * EC means equipment class (see c hapter 3 of the TSD) . DOE did not select any representative units from the single- phase, medium

- voltage equipment classes ( E C5 , EC7 and E C9 ), but calculated the analytical results for E C5 , E C7 , and EC9 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. DO E believes that this breakdown enables the analysis to identify and capture a more accurate representation of the manufacturer’s selling price and efficiency relationship . DOE broke dry- type distribution transformers into eight engineering design lines, pr imarily according to their BIL ratings

. DOE believes this level of disaggregation is necessary to capture important differences in the price-efficiency relationship, particularly as the BIL rating varies . For example, a 300 kVA, three- phase, dry -type unit could be classified in design lines 8, 9, or 11, or 13A, 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 13B, the representative units selected for some of the dry- type design lines may not be the standard BILs associated with a given primary voltage

. DOE selected a slightly higher BIL for the representative units from these design lines to ensure that any minimum efficiency standard would not excessively penalize customers purchasing transformers at higher BIL ratings within the range . For example, a 300 kVA transformer with a 4160V primary is called 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 achieve that same efficiency rating for customers ordering 60kV BIL . Thus, DOE evaluated the middle BIL rating (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 remainder of this section discusses each of the 14 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 833 kVA. Transformers in this design line typically have BILs ranging from 30 kV to 150 kV (this unit is 95 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 i n the primary in anticipation of an input voltage slightly above or below the rated nominal. This design line has a primary voltage less than 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.

Design Line 2 . This is the basic, high-volume line for round- tank (pole -mounted), singlephase, liquid-immersed distribution transformers, ranging from 10 kVA to 833 kVA. Altho ugh some manufacturers tend to employ the same basic core/coil design for design line 1 and design line 2, others may have design differences between pad -mounted and pole-mounted5-5 transformers . DOE decided to analyze these two types of distribution transfor mers separately for the engineering and LCC analyses . Transformers in design line 2 typically have BILs ranging from 30 kV to 150 kV (this unit is 125 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 line 2 is a 25 kVA pole-mounted unit, as this is a high

- volume rating for pole -mounted transformers.

Design Line 3 . This design line groups together single -phase, round-tank, liquidimmersed distribution transformers, ranging from 10 kVA to 833 kVA. Together, design lines 1 through 3 cover all the single-phase, liquid- immersed units . Transformers in this design line typically have BIL s rangin g from 30 kV to 150 kV (this unit is 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 des ign line 3 is a 500 kVA round- tank . 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 these transformers. Together, results from DL 1

- 3 are used to set standards for equipment class 1, single-phase liquid- immersed units.

Design Line 4 . Design line 4 represents rectangular tank, three-phase, liquid- immersed distribution transformers, ranging from 15 kVA to 2500 kVA. Transformers in this design line typic ally have BIL s ranging from 30 kV to 150 kV (this unit is 95 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 u nit selected for design line 4 is a 150 kVA transformer, as this is a common rating in this design line

. Design Line 5 . Design line 5 represents rectangular tank, three-phase, liquid- immersed distribution transformers, ranging from 750 kVA to 2500 kVA. Together, design lines 4 and 5 are scaled to cover all the three -phase, liquid- immersed units . Transformers in this design line typically have BIL s ranging from 95 kV to 150 kV (this unit is 125 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 . Together, design line 4 and design line 5 are used to determine standards for the whole kVA range in equipment class 2.

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 four below the nominal. DOE selected this tap arrange ment based on5-6 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 6 is used to generate results for equipment class 3.

Design Line 7

. Design line 7 represents three -phase, low-voltage, ventilated dry- type distribution transformers, ranging from 15 kVA to 1000 kVA. Transformers in this design line typically have BIL ratings of 10 kV and a “universal” tap arrangement, meaning six 21⁄2 percen t 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

. Design Line 8

. Design li ne 8 represents three -phase, low-voltage, ventilated dry- type distribution transformers, ran ging from 15 kVA to 2500 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 . DL8 and DL7 are used together to produce results for the entire kVA range of equipment class 4.

Design Line 9 . Design line 9 represents three-phase, medium-voltage, ventilated dry- type distribution transformers, ranging from 15 kVA to 2500 kVA. Transfor mers in design line 9 typically have primary voltages less than or 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 line 9 is 300 kVA, as this is a common rating in this size range.

Design Line 10 . Design line 10 represents three-phase, medium-voltage, ventilated drytype 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 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 this design line is a 1500 kVA transformer, as this is a common rating. Results from DL9 and DL10 are used together to scale to all of the kVA ratings in equipment class 6. Results from these two design lines are scaled to all of the kVA ratings in equipment class 5.5-7 Design Line 11 . Design line 11 represents three-phase, medium-voltage, ventilated drytype 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 considered the se higher BIL ratings separately

. 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 equal to 600 V.

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

Design Line 12 . Design line 12 represents three-phase, medium-voltage, ventilated drytype 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 equal to 600 V.

The representative unit selected for this design line is a 1500 kVA transformer, as it is a common rating in this s ize range and BIL rating . DL11 and DL12 are used to produce results for the entire kVA range of equipment class 8 and are scaled to equipment class 7.

Design Line s 13A and 13B . As a further extension on the dry-type, three-phase, mediumvoltage BIL ranges , DOE originally analyzed 96 kV to 150 kV BIL in two design lines ranging from 225 kVA to 2500 kVA. The 225 kVA rating 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
arrangemen t 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.

. 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 high end of the r ange covered by this design line. DL13A and DL13B are used to develop results for the full kVA range of equipment class 10, and scaled to set standards for equipment class 9.

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 5.1 , there are three equipment classes for single -phase, dry- ty pe, medium-voltage units. As discussed in chapter 3, the shipment volume for single-phase, dry-type, medium- voltage transformers 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 to5-8 the single -phase units. During the negotiations, DOE worked with various manufacturers and committee members to develop a new approach . In the end, D OE decided to scale the losses from each three -phase transformer to calculate losses and efficiency for the equivalently sized single

- phase transformer . Additional details and rationale appear in section 5.2.2 . In this way, DOE was able to concentrate resources and improve the accuracy in other, higher volume and more important distribution transformer equipment classes

.

5.2.1 Summary of Design Line Co verage
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 the table where the phrase “ DL X ” 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-ph ase

. The label “ DL 1 ” 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

- immersed transformer design lines, three single -phase and two three

phase, as shown in Table 5.3

. To capture any design differences between a single -phase pole and a pad -mounted transformer, DOE analyzed units in both DL1 and DL2, spanning the same kVA ratings (10 kVA to 833 kVA)

.

Table 5.3 Liquid

- Immersed Design Lines and Representative Units

Table 5.4 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 11 kVA ratings in th at equipment class

. kVA Design Line kVA Design Line

10 15 15 30 25 45 37.5 75 50 112.5 75 150 100 225 167 300 250 500 333 750 500 1000 667 1500 833 2000 2500 Equipment Class 1, Liquid-Immersed,

Single-Phase Equipment Class 2, Liquid-Immersed, Three-Phase

DL 1 DL 2

DL3 DL 5 DL 45-9 Table 5.4 Dry -Type, Low- Voltage Design Lines and Representative Units

As discussed in chapter 3, section 3.4 (National Shipment Estimate), medium-voltage, single -phase, dry- type units have a low shipment volume and low total MVA capacity

. All three medium-voltage, single phase, dry type equipment classes 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 a detailed analys is of any units from these three equipment classes.

Table 5.5 presents the equipment classes (abbreviated “ EC ” in this table) for the mediumvoltage, three-phase, dry-type distribution transformers and each of the design lines and respective representative units

. Because those equipment cla sses have high volume s and large
range s of kVA ratings, DOE used two separate design lines for each, to maintain accuracy. For DL13 A and DL13B, DOE did not extrapolate the results of th ese units to ratings of 150kVA and below because there were no shipment s at these ratings in the shipments analysis and it is very unlikely that they would be built. kVA Design Line kVA Design Line

15 15
25 30
37.5 45
50 75
75 112.5
100 150
167 225
250 300
333 500
750
1000 Equipment Class 3 Dry-Type, Low Voltage, Single-Phase Equipment Class 4 Dry-Type, Low Voltage, Three-Phase

DL 6

DL 7

DL 85- 10 Table 5.5 Dry

- Type, Medium

- Voltage, Three

- Phase Design Lines

5.2.2 Scaling Relationships 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 scaling factors is provided in Appendix 5B.

The scaling formulae are ma thematical 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 voltage and kVA rating

. For exam ple, when the kVA rating, voltage, and frequency are fixed, the product of theconductor current density, core flux density, core cross-sectional area, and total conductor crosssectional area is constant

. To illustrate this point, 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 windin gs 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 linear dimensions varies as the r atio 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 5.6 depicts the most common scaling relationships i n transformers. kVA EC 6 Low BIL EC 8 Med BIL EC 10 High BIL 20-45kV 46-95kV > 96kV
15

- 30

- 45

- 75

- 112.5

- 150

- 225
300
500
750
1000
1500
2000
2500 Dry-Type, Medium Voltage, Three-Phase

DL 9

DL 10 DL 11

DL 12 DL 13B DL 13A5- 11 Table 5.6 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 of conductor cross-section) in both the primary and secondary windings are all h eld 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 rules shown in Table 5.6 can be used 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

. Although these laws dictate that an ideal transformer will yield a scaling exponent of 0.75, DOE recognizes that a different exponent may produce better behaved results based on real

world engineering. For the NOPR, DOE used unique scaling exponents for each equipment class. For ea ch equipment class DOE derived an exponent to scale relative kVA rating by examining the proposals discussed during the negotiations. Because the proposals discussed during the negotiations included efficiency levels across multiple designs lines, a scalin g relationship was implied by the proposal. The exponents used for each equipment class are shown below in Table 5.7

. If one imagines the standard for a particular equipment class as a function on a plot of efficiency (y

- axis) versus kVA (x

- axis), then the efficiency levels in each design line are a series of points along an imaginary vertical line that intersects the x

- axis at the desi gn line’s kVA. If there is more than one design line in a given equipment class, there will be more than one series of points. Because exponential scaling is performed on losses and because exponential function will appear as straight lines on logarithmic plots, the concept is more tractable if illustrated that way, as is done in 5.2.1 below. Note that efficiency and loss values have a one

- to -one correspondence with eac h other, so one can use whichever coordinate is easier to illustrate identical information. Although standards are ultimately given in terms of efficiency, DOE5- 12 performs the scaling in loss coordinates. Also note that the following figures are given to illu strate the scaling concept, and have no relation to actual transformer data.

If one is to select efficiency levels for each design line, as was done by the negotiating committee for MVDT transformers, the task remains to scale those chosen efficiencies at certain kVA ratings to all of the other kVA ratings that DOE covers. Drawing a straight line 2 through the chosen points accomplishes that goal, but may produce a slope different from .75.

Deriving the .75 rule requires a number of assumptions to be made, among them that the overall form and proportions of the transformer remain intact as it changes in size. This assumption may break down in a number of ways. For example, MVDT BIL ratings require fixed spacings between the edge of a winding and the window of a core. Proportionally, these fixed values will be much larger for smaller transformers than for larger units. Thus, while the rest of the transformer may behave closer to what the .75 rule would predict, the “fixed” portion will cause losses to fall mo re slowly with decreasing kVA. Stated alternatively, losses will grow more slowly with increasing kVA and imply a scaling behavior of less than .75.

Figure 5.2.1 Efficiency Levels within an Equipment Class (Logarithmic)

2 A straight line in logarithmic space is an exponential in the original dimensions, which is the logical scaling behavior for transforme rs to exhibit.5- 13 Table 5.7 Scaling Exponents By Equipment Class Distribution Transformer Equipment Class Scaling Exponent 1. Liquid

- immersed, medium

- voltage, singl e

- phase .76 2. Liquid

- immersed, medium

- voltage, three

- phase .79 3. Dry

- type, low

- voltage, single

- phase .75 4. Dry

- type, low

- voltage, three

- phase

. 74 5. Dry

- type, medium

- voltage, single

- phase, 20

- 45 kV BIL .67 6. Dry

- type, medium

- voltage, three

- phase, 20

- 45 kV BIL .67 7. Dry

- type, medium

- voltage, single

- phase, 46

- 95 kV BIL .67 8. Dry

- type, medium

- voltage, three

- phase, 46

- 95 kV BIL .67 9. Dry

- type, medium

- voltage, single

- phase, > 96 kV BIL .68 10. Dry

- type, medium

- voltage, three

- phase, > 96 kV BIL .68

To illustrate how DOE used the scaling exponents, 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 ) E

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.” E = Scaling Exponent

and

Equation 5.2.2 TL 1 = TL 0 **×** (S 1 / S 0 ) E

where:

TL 1 = total losses of transformer “1,” and TL 0 = total losses of transformer “0.” E = Scaling Exponent

Equation 5.2.1 and Equation 5.2.2 can be manipulated algebraically to show that the load loss also varies to the “E” 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 “E” power. Specifically:5- 14 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:

Equation 5.2.4 LL 1 = (TL 0 **×** (S 1 / S 0 ) E ) - (NL 0 **×** (S 1 / S 0 ) E )

Equation 5.2.5 LL 1 = (TL 0 - NL 0 ) **×** (S 1 / S 0 ) E

Equation 5.2.6 LL 1 = (LL 0 ) **×** (S 1 / S 0 ) E

where:

LL 0 = load losses of transformer “0.”

Thus, kVA scaling 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, and 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 kVA scaling 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 scaling factors.

DOE used the kVA scaling to scale the analysis findings on each of the representative units within the 1 4 design lines to the 115 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 115 kVA ratings not analyzed.

5.3 TECHNICAL DESIGN INPUTS FOR SOFTWARE MODEL

For all 1 4 representative units, the engi neering 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 d esign since 1969. Using a range of input parameters and material prices, the OPS software produces a design . This design has specific information about the core5- 15 and coil, including physical characteristics, dimensions, 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 information 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 MSP 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 relationship between cost and efficiency because it provides detailed data on d esign 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 specific manufacturer . 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 known 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 customer's present value of future losses in the transformer core (no-load l osses)

. 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, respectively, and so the customer chooses a more
energy

- efficient transformer.

DOE used broad ranging combinations of A and B evaluation formulae (presented in Table 5.8 and Table 5.9 ) to create a complete set of efficiency levels for each design option combination analyzed. The efficiency levels spanned from a low

- first

- cost unit to a maximum technologically feasible (“ma x- 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 financial value to future losses in the core or coil of the transformer. For the maximum technologically feasi ble design, the A and B evaluation values were very high, pushing the software to design at the highest efficiencies achievable.

DOE created its combinations 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 value of A5- 16 by a step value, and then increasing the B value from zero to that value of A, using a different
st ep 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 5.8 presents the ranges and incremental steps for the A and B combinations used in the three grids.

Table 5.8 A and B Grid Comb inations 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 which 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 times (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 we re calculated as fractions of A so that the ratio of A to B encompassed 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 percent, 35 percent, 40 percent, 45 percent, 50 percent, 55 percent, and 60 percent. Table 5.9 presents the range of the two fan combinations used in the analysis

.

Table 5.9 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 unit studied.5- 17 Figure 5.3.1 A and B Combination Software Inputs Used in the Engineering Analysis

Occasionally, the design software generated the same transformer design for 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 anal ysis

. 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 . Depending 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 winding materials . To capture this variation in design, DOE analyzed the 14 representative units using 8 – 14 different design option combinations of core type, core steel, and winding material. As discussed in the technology assessment (see c hapter 3), core steel 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. M12 core steel is5- 18 non-oriented grain sil icon steel and is rolled in thicker laminations, thus contributing to higher core losses

. Table 5.10 lists all the steel types used in the analy sis, 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 5.10 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

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

- oriented silicon steel

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 5.11 provides a list of all the core configurations used for each of the 14 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- 19 Table 5.11 Core Configurations Used in Each Design Line

Design Line # Phases Core Configurations Used in the Engineerin g Analysis

DL1 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; 5

- leg

DL5 3 Wound core

- distributed ga p ; 5

- leg

DL6 1 Wound core

– distributed gap; or s tacked butt

- lap ; S hell

- type or core

- type

DL7 3 Wound core

- distributed gap; or s tacked butt

- lap

, step

- lap or full mitered ; 3

- leg or 5

- leg

DL8 3 Wound core

- distributed gap; or stacked butt

- lap

, step

- lap or full mitered; 3

- leg or 5

- leg

DL9 3 Wound core

- distributed gap; or stacked full mitered ; 3

- leg or 5

- leg

DL10 3 Wound core

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

- leg

DL11 3 Wound core

– distributed gap; or s tacked

, step

- lap or full mitered; 3- leg or 5

- leg

DL12 3 Wound core

– distributed gap; or s tacked, cruciform or step

- lap mitered joint ; 3

- leg or 5

- leg DL13 (A & B) 3 Wound core

– distributed gap; 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 performance impact of the lamination joint gaps (reducing the exciting current) and, by locating inside the coil window, reduce the transformer’s operating sound lev el

. Figure 5.3.2 illustrates the two types of single

- phase core construction.5- 20 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 co nstruction for the three-phase liquidimmersed transformers . Some of the dry-type designs using an amorphous core also use a fivelegged construction technique. Figure 5.3.3 below illustrates the difference between the three

legged and 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 more 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

- miterin g,” “full

- mitering,” and “step

- mitering.” DOE modeled full

- mitered 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 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, depending on the design. By using a

core con figuration 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 the5- 21 primary winding being delta

- connected . If the primary winding is wye-c onnected, 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

Transformers with symmetric core configurations use continuously wound cores with 120 degree radia l symmetry, where no one leg is magnetically distinguishable from the other two

. . Following the preliminary analysis, DOE was unable to identify a company with commercial modeling software that c ould model symmetric core designs. DOE did sp eak with transfo rmer 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 industry expe rts

. . However, because the data was so limited and DOE did not receive any additional information from manufacturers, DOE did not consider symmetric core designs in this stage of the rulemaking

. .5- 22 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. DOE 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 with 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 certain degree of fire protection or LNAN for users who prefer an extra measure of safety, DOE will continue to refer to bot h KNAN and LNAN using the phrase ‘less

- flammable,’ or LFLI.

DOE understands that the viscosity of the insulating liquid can have a slight 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 contributing to a slightly higher load loss. Howeve r, as efficiency increases, the transformer will run cooler, which negates part of the need for larger cooling ducts. As such, LFLI transformers 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 higher efficiencies than mineral oil units since their higher temperature tolerance may allow the unit to be downsized and r un hotter than mineral oil units.

For the KNAN transformers (i.e., those with a fire point of 300 degrees or greater), DOE is not aware 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 no fire point), DOE understands that the viscosity under usual operating conditions 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 operating temperature, which could allow the transformer to be downsized and run hotter. This would negate any impact on effici ency

. 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 833 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  ̊C5- 23 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 BIL: 95 kV

For DL1, DOE selected nine design option combinations, based on input from manufacturers and other technical 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 combinations to represent the most common construction practices for this representative unit.

Table 5.12 Design Option Combinations for the Design Line 1 Representative Unit

Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Des ign 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 woundin such a way that the gap between the start and finish of a lamination is staggered in the crosssection of the core.

DOE analyzed each of the nine design option combinations using the matrix of A and B values descri bed in Table 5.8 and Table 5.9 , creating 1,924 designs.

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 833 kVA

. The representative unit selected for this design line is a 25kVA pole-mounted unit. The following are the tec hnical 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- Typ e), Lo

- Hi (Core -Type, for amorphous core)5- 24 Core: Wound core - distributed gap Taps: Four 21⁄2 percent, two above and two below the nominal Impedance Range: 1.0 –4 .5 percent BIL: 125 kV

For DL2, DOE 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 5.13 Design Option Combinations for the Design Line 2 Representative Unit

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 5.8 and Table 5.9 , creating 2,301designs.

5.3.7 Design Line 3 Representative Unit

Design line 3 (DL3) represents round-tank, liquid- immersed, single

- phase distribution transformers, ranging from 10 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:

KVA: 500 (liquid-immersed, round-tank) Primary: 14400 Volts at 60 HZ (150kV BIL) Secondary: 277 Vo lts 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 percent BIL: 1 50 kV5- 25 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 combinations to represent the
most common construction practice for this representative unit.

Table 5.14 Design Option Combinations for the Design Line 3 Representative Unit

Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Desi gn 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 5.8 and Table 5.9 , creating 2,740 designs.

5.3.8 Design Line 4 Representative Unit

Design line 4 (DL4) represents rectangular tank, liquid- immersed, three -phase distribution transformers, ranging from 15 kVA to 2500 kVA. The representative unit selected for this design line is a 150kVA transformer. The following are the technical specifications that constitute inp ut parameters to the OPS design software:

KVA: 150 (liquid-immersed, pad mount) Primary: 12470Y/7200 Volts at 60 Hz (95kV BIL) Secondary: 208Y/120 Volts T Rise: 65  ̊C Ambient: 20  ̊C Terminal Configuration: ANSI/IEEE C57.12.26, Loop Feed Winding Configurat ion: 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 BIL: 9 5 kV5- 26 For DL4, DOE selected nine design option combinations of core steel and winding typesbased on input from manufacturers and other technical experts. With the exception of the maxtech/high -efficiency designs, DOE selected these design option combinations to represent the most common construction practice for the representative unit.

Table 5.15 Design Option Combinations for the Design Line 4 Representative Unit

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 5.8 and Table 5.9 , creating 1,977 designs.

5.3.9 Design Line 5 Representative Unit

Design line 5 (DL5) represents rectangular tank, liquid- immersed, three -phase distribution transformers, ranging from 15 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 Configuration: 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 BIL: 125 kV

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 of the max

- tech/high

- efficiency designs, DOE selected these design option combinations to represent the most common construction practices for the representative unit.5- 27 Table 5.16 Design Option Combinations for the Design Line 5 Representat ive Unit

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 5.8 and Table 5.9 , 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 specifications 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: Lo- 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 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 practic e for the representative unit.5- 28 Table 5.17 Design Option Combinations for the Design Line 6 Representative Uni t

Core Material High

- Voltage Conductor Low

- Volt age 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 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 Cu

– wire Cu

– wire Stacked Core Butt

- lap 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 ten design option combinations using the matrix of A and B values described in Table 5.8 and Table 5.9 , creating 3,091 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 1000 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 fifteen design option combinations of core steel and winding material, based on input from manufacturers and other technical experts. With the exception o f the max

- tech/high -efficiency designs, DOE selected these design option combinations to represent the most common construction practice for the representative unit.5- 29 Table 5.18 Design Option Combinations fo r the Design Line 7 Representative Unit

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 Al

– wire Al

– wire 3

- Leg Stacked Butt

- lap M4 Al

– wire Al

– wire 3

- Leg Step

- Lap 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 Cu

– wire Cu

– wire 3

- Leg Stacked Butt

- lap H

- 0 DR * Al

– wire Al

– strip 3

- Leg Stacked Full Miter H

- 0 DR Al

– wire Al

– strip 3

- Leg Step

- Lap Miter 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 fifteen design option combinations using the matrix of A and B values described in Table 5.8 and Table 5.9 , creating 1990 designs.

For the NOPR, DOE filtered out a number of transformer designs with high flux density from DL7

. Based on comments in negotiations, DOE removed designs over a certain flux density to maintain consistency with designs submitted by manufacturers. There is a variety of reasons that manufacturers would choose to limit flux density (e.g. vibration and noise). Designs using conventional steels begin to experience these issues at flux densities over 1.3 T esla ; while those with domain

- refined high permeability core steels see issues starting at 1.5 T esla

. Designs that use amorphous metal have naturally lower flux densities, and therefore do not often experience
t hese issues

. DOE set the flux density limitations described in Table 5.19

.5- 30 Table 5.19 Limits on Flux Den si ty for Design Line 7 Representative Unit Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type Flux Density Limit M12 Al

– wire Al

– wire 3

- Leg Stacked Butt

- lap 1.3 M12 Cu

– wire Al

– wire 3

- Leg Stacked Butt

- lap 1.3 M6 Al

– wire Al

– wire 3

- Leg Stacked Butt

- lap 1.3

M6 Al – wire Al – wire 3

- Leg Stacked Full Miter** 1.3

M4 Al

– wire Al

– wire 3

- Leg Stacked Butt

- lap 1.3 M4 Al

– wire Al

– wire 3

- Leg Step

- Lap Miter 1.3 M4 Cu

– wire Al

– wire 3

- Leg Stacked Full Miter 1.3 M3 Al

– wire Al

– wire 3

- Leg Stacked Full Miter 1.3 M3 Al

– wire Al

– wire 3

- Leg Step

- Lap Miter 1.3 M3 Cu

– wire Cu

– wire 3

- Leg Stacked Butt

- lap 1.3 H

- 0 DR * Al

– wire Al

– strip 3

- Leg Stacked Full Miter 1.5 H

- 0 DR Al

– wire Al

– strip 3

- Leg Step

- Lap Miter 1.5 H

- 0 DR Cu

– wire Cu

– wire 3

- Leg Stacked Full Miter 1.5 SA1 (Amorphous) Al – wire Al – strip 5- Leg DG Core No limit set

SA1 (Amorphous) Cu – wire Cu – wire 5- Leg DG Core No limit set

5.3.12 Design Line 8 Representative Unit

Design line 8 (DL8) represents ventilated dry- type, three -phase, low-voltage distribution transformers, ranging from 15 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) De lta 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 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 common construction practice for the representative unit.5- 31 Table 5.20 Design Option Combinations for the Design Line 8 Representative Unit

Core Material High

- Voltage Cond uctor Low

- Voltage Conductor Core Design Type

M6 Al

– wire Al

– strip 3

- Leg Stacked Butt

- lap M6 Al

– wire Al

– strip 3

- leg Stacked Full Miter 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 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 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 fourteen design option combinations using the matrix of A and B values described in Table 5.8 and Table 5.9 , creating 4,443 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 2500 kVA. The representa tive 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 sel ected thirteen design option combinations of core steel and winding material, based on input from manufacturers and other technical experts. With the exception of5- 32 the max

- tech/high -efficiency designs, DOE selected these design option combinations to
repres ent the most common construction practice for the representative unit

.

Table 5.21 Design Option Combinations for the Design Line 9 Representative Unit

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 M4 Al

– wire Al

– wire 3

- Leg Step

- Lap 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 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 5.8 and Table 5.9 , creating 5,600 designs.

5.3.14 Design Line 10 Representative Unit

Design line 10 (DL10) represents dry- type, three -phase, medium- voltage distribution transformers with a 20

- 45kV BIL, ranging from 15 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 inpu t 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 percent5- 33 For DL10, DOE selected eleven design option combinations of core steel and winding material, based on input from manufacturers and other technica l 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 5.22 Design Option Combinations for the Design Line 10 Representative Unit

Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type

M5 Cu

– wire Al

– strip 3

- Leg Mitered Cruciform M4 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter 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 eleven design option combinations using the matrix of A and B values described in Table 5.8 and Table 5.9 , creating 2,501 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 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: 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 Impeda nce 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 of5- 34 the max

- tech/high

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

.

Table 5.23 Design Option Combinations for the Design Line 11 Representative Unit

Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type

M6 Cu

– wire Cu

– strip 3

- Leg Stacked Full Miter** M4 Al

– wire Al

– strip 3

- Leg Step

- Lap 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 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 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 5.8 and Table 5.9 , creating 1,896 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 15 kVA to 2500 kVA. The representative unit selected for this design line is a 1500 kVA transformer. The following are the tec hnical 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: Stac ked, 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 materi al, based on input from manufacturers and other technical experts. With the exception of5- 35 the max

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

.

Table 5.24 Design Option Combinations for the Design Line 12 Representative Unit

Core Material High

- Voltage Conductor Low

- Voltage Conductor Core Design Type

M5 Al

– wire Al

– strip 3

- Leg Mitered Cruciform M4 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter 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 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 5.8 and Table 5.9 , creating 3,393 designs.

5.3.17 Design Line 13 A Representative Unit

Design line 13A (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:

K VA: 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, 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 DL13A , 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

.5- 36 Table 5.25 Design Option Combinations f or the Design Line 13A Representative Unit

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 M4 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter 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 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 5.8 and Table 5.9 , creating 831 designs.

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 the 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 DL13B , DOE selected eight 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- 37 Table 5.3.20 Design Option Combinations for the Design Line 13B Represen tative Unit

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 M4 Al

– wire Al

– strip 3

- Leg Step

- Lap Miter 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 eight design option combinations using the matrix of A and B values described in Table 5.8 and Table 5.9 , creating 1,881 designs.

5.3.19 Newly Optimized Designs and Previously Optimized Designs

For the NOPR, DOE utilized a combination of newly optimized design runs and designs that were optimized during the preliminary 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.

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 p rices are applied to them.

DOE updated the cost of these previous design runs by applying updated prices to the design’s bill of materials

. Effectively, DOE calculated the present cost of developing the same design that was used in the preliminary analysi s. DOE also updated labor prices and applied the markups consistently with any newly optimized designs generated for the NOPR analysis. DOE carried over the NOPR analysis to the Final Rule unchanged.

5.4 MATERIAL AND 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 5.4 , where production costs and non- pro duction costs are combined to determine the manufacturer’s selling price of the equipment.5- 38 Figure 5.4.1 Method of Cost Account for Distribution Transformers Rulemaking

Together, 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 representatives, logistics), research and developme nt (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 estimate of the manufacturer’s selling price.

DOE us ed 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 th is 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 through meetings and dialogue with transformer manufact urers 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, insulation). It accounts for the handling 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 accounts for breakage of prefabricated amorphous cores and any scrap associated with assembling the windings on the core. Since amorphous cores are assumed 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- 39 **•** 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 en ergy use (e.g., annealing furnace), taxes, and insurance. DOE only applied factory overhead to the direct material production
costs.

**•** Shipping: $0.28 per pound for each transformer. The shipping costs include the freight from a manufacturer’s facility to t he 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 2011.

**•** 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 . DOE applied the non-production markup to the sum of dire ct 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 ma terials, including M6 core steel, copper primary and secondary windings, and all the transformer hardware. There are approximately 27 hours of labor involved in manufacturing this design, resulting in a labor cost of $1,361. 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 $504, 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 overhe ad, and shipping costs (i.e., 25 percent of $4,795 + $1,391 + $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 critical because the manufacturer’s selling prices calculated in the engineering analysis are based on a bill o f materials that includes, for example, specifications for pounds of steel, pounds of conductor, gallons of mineral oil, and tank dimensions. Therefore, as material prices increase, so will the manufacturer’s selling price.5- 40 Furthermore, as discussed in cha pter 3, energy -efficient transformers tend to incorporate more materials (e.g., pounds of core steel, pounds of conductor), making the impact of more expensive 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 suppliers and wholesalers. Although not all transformer manufacturers pay the same amount per pound for el ectrical -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 conductor 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 it could develop conductor prices by establishing a processing “adder,” or a cost required to form the finished good from the underlying commodity. The adder would change much more slowly than the price of the processed commodity and would allow DOE to derive conductor prices by summing the processing adder and the price of the underlying commodity obtained from exchanges such as COMEX and London Metal Exchange (LME) . DOE intends to continue deriving conductor prices in this manner in future updates to the analysis. For the NOPR and Final Rule, DOE used this approach.

Prior to the NOPR, DOE conducted the engineering 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 signifi cant impact on the total cost of the distribution transformer. All transformer designs that were newly optimized used the current 20 10 material price, which DOE used as one of its reference cases. The maximum and minimum prices were then applied to these s ame designs to generate a manufacturer selling price for each of those scenarios. The results of the current 2010 material prices are presented here in chapter 5, while the results of the minimum and maximum material prices are presented in Appendix 5C.

For the NOPR, based on discussions in negotiations, DOE decided to implement a second reference case, using 2011 material prices . The 2011 steel prices were developed using manufacturer feedback gathered in interviews and during the negotiation process. Rel ative to the 2010 prices, 2011 steel prices were lower, particularly for M2 grade steel and worse. Results from the 2011 price trend are also presented here in chapter 5.

DOE noted that the price of the most critical material input to a distribution trans former, electrical core steel, had varied significantly for some M -grades over the five-year time horizon. For this reason, DOE researched the grain

- oriented electrical steel market to gain a better5- 41 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, which included material prices. In chapter 8, the 2008 + 25% material price scenar io is referred to as the “high” price scenario, the 2010 and 2011 price scenario s are called “medium” price scenario s, and the 2006 – 25% material price scenario is referred to as the “low” price scenario. DOE originally chose to utilize the current 2010 m aterial price in the reference case 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 average price. In the NOPR analysis, DOE added 2011 pr ices as a second reference case based on negotiator feedback. 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 and engineering spreadsheets.

5.4.2 Material Price Inputs to the Design Software – Liquid

- Immersed

Table 5.26 presents the material prices for a typical manufacturer of liquid

- immersed transformers

. All design s were opti mized on a set of 2010 prices. After optimization, slight adjustments were made to 2010 prices, and a 2011 price scenario was developed. Both of these reference scenarios are presented along with a minimum and maximum price scenario.5- 42 Table 5.26 Typical Manufacturer’s Material Prices for Liquid

- Immersed Design Lines

Item and Description 2010 Price 2011 Price Min Price (2006 - 25%) Max Price (2008 + 25%) M6 core steel 1.33 1.04 0.94 2.19 M5 core steel 1.38 1.10 0.99 2.24 M4 core steel 1.45 1.20 1.03 2.30 M3 core steel 1.88 1.30 1.06 2.60 M3 Lite Carlite core steel 1.95 1.95 1.47 2.44 M2 core steel 2.00 1.40 1.32 2.79 M2 Lite Carlite core steel 2.10 2.10 1.58 2.63 ZDMH (mechanically

- scribed core steel) 2.05 1.90 1.41 3.22 SA1 (amorphous)

- finished core, volume production 2.38 2.20 1.72 3.64 Copper wire, formvar, round #10

- 20 4.87 4.87 3.33 5.97 Copper wire, enameled, round #7

- 10 4.84 4.84 3.31 5.93 Copper wire, enameled, rectangular sizes 4.97 4.97 3.41 6.09 Aluminum wire, formvar, round #9

- 17 3.07 3.07 2.30 3.91 Aluminum wire, formvar, round #7

- 10 2.57 2.57 1.93 3.28 Copper strip, thickness range 0.02

- 0.045 4.97 4.97 3.41 6.09 Copper strip, thickness range 0.030

- 0.060 4.97 4.97 3.41 6.09 Aluminum strip, thickness range 0.02

- 0.045 2.08 2.08 1.56 2.67 Aluminum strip, thickness range 0.045

- 0.080 2.08 2.08 1.56 2.67 Kraft insulating paper with diamond adhesive 1.52 1.52 1.17 1.93 Mineral oil 3.35 3.35 1.94 3.84 Tank Steel 0.38 0.38 0.32 0.60

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 of importing finished cores from overseas. Since that time, several North American core manufacturers have begun producing amorphous cores. For the preliminary analysis and NOPR, 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 inp uts 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, bas ed on the optimized transformer design (the software considers this variable) and the labor necessary to build the tank

. Table 5.27

s ummarizes all the estimated fixed material costs and estimates of the tank costs for each of the five liquid

- immersed design lines.5- 43 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 copper studs, 240/120V, 50 kVA, costing $30 for the set. Interna l 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 approximately $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 $73.

For DL3, a 500kVA single-phase 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), nameplate ($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 $629 (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-voltage bushings are three copper studs at $8 each. The internal h ardware 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 app roximately $389.

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 $1,016.

Table 5.27 Summary Table of Fixed Material Costs f or Liquid

- Immersed Units Item DL1 DL2 DL3 DL4 DL5 High voltage bushings $28 $6 $6 $21 $60 Low voltage bushings $30 $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 ~$629 ~$389 ~$1,0165- 44 * 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 co oling surface area.

5.4.3 Material Price Inputs to the Design Software – Dry -Type

Table 5.28 presents the material prices for a typical dry

- type transformer manufacturer in dicating the reference cases (2010 and 2011 prices), minimum (2006), and maximum (2008) prices (all in constant 2010$).

Table 5.28 Manufacturer’s Material Prices for Dry

- Type Design Lines

Item and Description 2010 Price 2011 Price Min Price (2006 - 25%) Max Price (2008 + 25%) M36 core steel (26 gauge) 0.60 0.66 0.46 0.84 M19 core steel (26 gauge) 0.83 0.91 0.56 1.19 M12 core steel 0.95 0.78 0.85 1.60 M6 core steel 1.33 1.04 0.94 2.19 M5 core steel 1.38 1.10 0.99 2.24 M4 core steel 1.45 1.20 1.03 2.30 M3 core steel 1.88 1.30 1.06 2.60 M2 core steel 2.00 1.40 1.32 2.79 H

- 0 DR core steel (laser

- scribed) 2.06 1.70 1.41 3.23 SA1 (amorphous)

- finished core, volume production 2.38 2.20 1.72 3.64 Copper wire, rectangular 0.1 x 0.2, Nomex wrapped 4.52 4.52 3.07 5.53 Aluminum wire, rectangular 0.1 x 0.2, Nomex wrapped 2.97 2.97 2.23 3.78 Copper strip, thickness range 0.02

- 0.045 4.97 4.97 3.41 6.09 Aluminum strip, thickness range 0.02

- 0.045 2.08 2.08 1.56 2.67 Nomex insulation (per pound) 24.50 24.50 13.72 29.03 Cequin insulation (per pound) 5.53 5.53 3.84 6.09 Impregnation (per gallon) 22.55 22.55 17.16 27.31 Winding Combs (per pound) 12.34 12.34 6.08 15.41 Enclosure Steel (per pound) 0.38 0.38 0.32 0.60

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 DL 8. The adders specified an extra 10 cents per pound of core steel for full-mitered designs. More detailed costing of the retooling costs for mitering equipment will be covered in the manufacturer impact analysis (MIA). (See chapter 12.)5- 45 Similar to the li quid- 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 5.29

. 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 ventilated enclosure – a 16

- 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 t he transformer enclosure 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 mou nting feet – varies with the size of the core

- coil assembly for the 75kVA 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 $0.42 per foot. DO E 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 300kVA unit, and costs approximately $100.

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 (lowvoltage) 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 dogbone 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 s et costs $120. DOE estimated the low-voltage busbar 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 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 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 $230.5- 46 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 14

- 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 lowvoltage 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 mounting 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 $200.

For DL12, a 1500 kVA three-phase, medium-voltage, dry-type at 95 kV BIL, the lowvoltage a nd high-voltage 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 enclos ure 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 t he 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 700 pounds on average and costs approximatel y $2 70. 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 14 -gauge steel enclosure, base, and mounting feet – varies with the size of the

core -coil assembly for the 1500 kVA unit, and costs approximately $450.

For DL13A, a 300 kVA three-phase, medium-voltage, dry-type at 125 kV BIL, the lowvoltage and high-voltage terminal set costs $115. The high-voltage terminal boards cost $27. DOE esti mated the low -voltage bus-bar is estimated to be 10 feet at $10 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. DOE estimated the miscellaneous hardware costs at $36. The ventilated enclosure – a 14

- gauge steel enclosure, base, and mounting feet – varies with the size of the core

- co il assembly for the 300 kVA unit, and costs approximately $200.

For DL13B, a 2000 kVA three-phase, medium- voltage, dry -type at 125 kV BIL, the lowvoltage and high-voltage terminal set costs $150. The high-voltage terminal boards cost $27. DOE estimated t he low-voltage bus-bar is estimated to be 18 feet at $15 per foot, or $270. The mounting 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 designs. This extra bracing is needed for the amorph ous design due to the size of DL1 3B (2000 kVA). The weight of the added bracing was calculated as 7 percent of the cor e and coil weight, and was multiplied by the price for enclosure steel to derive a cost. The added bracing weighs 850 pounds on average5- 47 and costs approximately $330. The fiberglass dog-bone duct-spacers used for this design line cost $0.60 per foot. DOE estimated the miscellaneous 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 unit, and costs approximately $450.5- 48 Table 5.29 Summary Table of Fixed Material Costs for Dry

- Type Units

Item DL 6 DL 7 DL 8 DL9 DL10 DL11 DL12 DL13 A DL13 B LV and HV terminals (set) $4 n/a n/a $75 $120 $100 $135 $115 $150

HV terminal board(s) n/a $27 $27 $27 $27 $27 $27 $27 $27

LV bus- bar n/a $10. 50 $22.5 0 $80 $140 $80 $192 $100 $270
Core/coil mounting frame $9.2 5 $19 $36 $36 $120 $42 $125 $50 $175

Additional Bracing n/a n/a n/a n/a ~$ 23 0 n/a ~$ 27 0 n/a ~$ 330

Nameplate $0.6 5 $0.6 5 $0.65 $0.65 $0.65 $0.65 $0.65 $0.65 $0.65
Dog

- bone duct spacer (ft.) $0.2 4 $0.3 2 $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. 0 0 $10. 0 0 $10.00 $10.00

Misc. hardware $4.5 0 $7 $12 $25 $42 $32 $54 $36 $60
Enclosure (12, 14 gauge) ~$ 5 0 ~$ 9 0 ~$ 10 0 ~$ 13 5 ~$ 40 0 ~$ 20 0 ~$ 45 0 ~$ 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 trans formers

. It developed the hourly cost of labor using a similar approach to the development of the cost of materials; however, it used different markups. DOE developed the markups shown in Table 5.30 after reviewing publicly available information , speaking with transformer manufacturers during 2011, and consulting with industry experts familiar with transformer manufacturing in the U.S.5- 49 Table 5.30 Labor Markups for Liquid

- Immersed and Dry

- Type Manufacturers

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 - Det ailed 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 factor 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.

5.4.4.1 Liquid

- Immersed Labor Hours

There ar e 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 a mount of time dedicated to each is given in Table 5.31

.

**•** 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 cutting, forming, and annealing to zero.5- 50 **•** 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 simul taneously on the same winding machine. This manufacturing approach improves 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 di stribution (step

down) transformer, 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 t his 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 them 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. Le ad 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 rati ng, but does not vary with efficiency. 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 approxima tely 0.2 hours (for DL2) to 4.9 hours (for 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. On5- 51 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 tim e for this activity does not vary with design 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.

**•** Inspect ion – This activity involves verifying th at 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, cor e 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 oi l. 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.

**•** Pa llet 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 tim e 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 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 from 0.08 to 0.35 hours.

Table 5.31 summarizes the estimates of labor time that DOE used for the five liquidimmersed units.5- 52 Table 5.31 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

5.4.4.2 Dry -Type Labor Hours

Likewise, there are several labor steps involved in manufacturing a dry- type transformer

. For the preliminary analysis, DOE prepared estimates of the amount of labor involved, some varying with the transformer design and others fixed on a per-unit basis. . For the NOPR analy sis DOE modified its approach based on comments in negotiations, and calculated a core labor estimate based on the weight of the transformer. . In addition, DOE prepared a constant labor hour value for all other labor steps involved. . This value was held constant for all designs within a design line and was prepared based on data and feedback from manufacturers in negotiations. These steps are described below

.

**•** Core Stacking – This task involves stacking (assembling) the cut steel laminations into a distri bution 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

.

**•** Primary Winding – This task encompasses winding the primary conductor of the transformer

. It includes set

- up time as well as winding time

.

**•** Secondary Winding – This task involves winding the secondary conductor of the transformer

. It includes set

- up time as well as winding tim e. The winding time of the secondary is considerably 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

.

**•** Lead Dr essing – 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- 53 removed to enable good electrical connection and insulating tubing is slipped over the cable

.

**•** Asse mbly – 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 kVA rating.

**•** Inspection – This activity involves verifying that the transformer 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.

**•** Preliminary Test – This step involves conducting a test to ensure that the core/coil meets the specified turns ratio, polarity, core loss, etc. .

**•** 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.

**•** Enclosure Manufacturing – The labor estim ate for this task encompasses all activity associated with the cutting, forming, assembly, priming, painting, and preparation of the enclosure.

**•** Packing – 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.

**•** 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.

During negotiations, DOE learned that mitering, particularly step

- lap mitering, results in a higher cost per pound of core steel than butt-lapping. . In response, DOE incorporated a
process ing adder for mitered designs for both low- and medium-voltage dry- type designs . . In the medium- voltage case, DOE incorporated a proce ssing adder of 10 cents per pound for step- lap mitering . . In the low- voltage case, DOE incorporated a proc essing cost of 10 cents per pound for ordinary mitering and 20 cents per pound for step- lap mitering

. . Different processing adders were used for low-voltage and medium-voltage to account for the fact that the base case design option is different. . In low -voltage units, DOE modeled butt-lapped designs at the baseline efficiency level whereas ordinary mitering was modeled at the baseline for medium -voltage. . These changes were applied to all dry

- type design lines

. .5- 54 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 efficiency 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 stand ards.

5.5.1 Criteria for Developing Efficiency Levels

After the preliminary analysis, DOE developed efficiency levels for each design line

. . To accomplish this, DOE first found the range of efficiencies possible for each design line, ranging from the baseline to max

- tech, and selected ELs as evenly spaced as possible for each design line

. While selecting the ELs, Doe also considered the efficiency potential of non -amorphous core steels and other benchmarks such as NEMA premium levels . As much as possible, DOE i ncorporated these benchmarks into their selections

.

5.5.2 Efficiency Levels Selected

Table 5.32 presents the efficiency levels (ELs) identified for each design line in the engineering analysis.

Table 5.33 and Table 5. 34 present the incremental MSP for each of the least -costly design options at each efficiency level using 2010 prices and 2011 prices respectively.5- 55 Table 5.32 Summary of Baselines and Efficiency Levels for Distribution Transformer Representative UnitsDL Representative Unit Baseline EL1 EL2 EL3 EL4 EL5 EL6 EL7
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 99.47

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 98.93 99.04 99.15 99.22 99.39 99.55 99.55

10 1500 kVA, 150 **°** C, three

- phase, 60Hz, 4160V primary, 480Y/277V secondary, 45kV BIL 99.22 99.29 99.37 99.45 99.51 99.58 99.63 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 99.63

13A 300kVA, 150  ̊C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL 98.63 98.69 98.84 98.97 99.04 99.25 99.45 99.45

13B 2000kVA, 150  ̊C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL 99.15 99.19 99.28 99.38 99.45 99.52 99.58 99.625- 56 Table 5.33 Summary of 2010 Incremental Manufacturer Selling Prices Over the Baseline for Distribution Transformer Representative UnitsDL Representative Unit Baseline EL1 EL2 EL3 EL4 EL5 EL6 EL7

$ $ $ $ $ $ $ $

1 50 kVA, 65 **°** C, single

- phase, 60Hz, 14400V primary, 240/120V secondary, rectangular tank - 199 666 811 339 823 1168 N/A

2 25 kVA, 65 **°** C, single

- phase, 60Hz, 14400V primary, 120/240V secondary, round tank - 216 397 215 247 487 708 1185

3 500 kVA, 65 **°** C, single

- phase, 60Hz, 14400V primary, 277V secondary - 849 935 2481 1606 2131 4139 7002

4 150 kVA, 65 **°** C, three

- phase, 60Hz, 12470Y/7200V primary, 208Y/120V secondary - 574 1328 2211 1413 1164 1893 4681

5 1500 kVA, 65 **°** C, three

- phase, 60Hz, 24940GrdY/14400V primary, 480Y/277V secondary - 3472 3881 5886 6585 9350 25704 N/A

6 25 kVA, 150 **°** C, single

- phase, 60Hz, 480V primary, 120/240V secondary, 10kV BIL - 20 153 235 361 404 582 1144

7 75 kVA, 150 **°** C, three

- phase, 60Hz, 480V primary, 208Y/120V secondary, 10kV BIL - 1503 701 929 565 745 950 2157

8 300 kVA, 150 **°** C, three

- phase, 60Hz, 480V Delta primary, 208Y/120V secondary, 10kV BIL - ( 844 ) ( 107 ) 1030 1937 3282 2371 7372

9 300 kVA, 150 **°** C, three

- phase, 60Hz, 4160V Delta primary, 480Y/277V secondary, 45kV BIL - ( 422 ) ( 406 ) 577 1392 1933 4508 N/A

10 1500 kVA, 150 **°** C, three

- phase, 60Hz, 4160V primary, 480Y/277V secondary, 45kV BIL - 290 2565 7501 13638 17260 22868 N/A

11 300 kVA, 150 **°** C, three

- phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL - ( 322 ) 1245 2149 2142 4003 7952 N/A

12 1500 kVA, 150 **°** C, three

- phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL - 1426 2878 7726 9313 12199 18482 2634 6

13A 300kVA, 150  ̊C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL - 381 1409 4592 4780 7090 13256 N/A

13B 2000kVA, 150  ̊C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV - ( 162 ) 5848 12562 19966 27890 N/A N/A5- 57 BIL

Table 5.34 Summary of 2011 Incremental Manufacturer Selling Prices Over the Baseline for Distribution Transformer Representative UnitsDL Representative Unit Baseline EL1 EL2 EL3 EL4 EL5 EL6 EL7

$ $ $ $ $ $ $ $

1 50 kVA, 65 **°** C, single

- phase, 60Hz, 14400V primary, 240/120V secondary, rectangular tank - 170 651 794 472 923 1253 N/A

2 25 kVA, 65 **°** C, single

- phase, 60Hz, 14400V primary, 120/240V secondary, round tank - 209 378 272 302 531 749 1232

3 500 kVA, 65 **°** C, single

- phase, 60Hz, 14400V primary, 277V secondary - 841 1581 3104 2280 2764 4675 7394

4 150 kVA, 65 **°** C, three

- phase, 60Hz, 12470Y/7200V primary, 208Y/120V secondary - 460 1282 2218 1375 1090 1793 4573

5 1500 kVA, 65 **°** C, three

- phase, 60Hz, 24940GrdY/14400V primary, 480Y/277V secondary - 4037 4394 6341 7045 9703 26145 N/A

6 25 kVA, 150 **°** C, single

- phase, 60Hz, 480V primary, 120/240V secondary, 10kV BIL - 25 126 214 362 403 572 1117

7 75 kVA, 150 **°** C, three

- phase, 60Hz, 480V primary, 208Y/120V secondary, 10kV BIL - 1428 568 690 421 645 886 2025

8 300 kVA, 150 **°** C, three

- phase, 60Hz, 480V Delta primary, 208Y/120V secondary, 10kV BIL - (768) (69) 619 1652 3062 2490 7359

9 300 kVA, 150 **°** C, three

- phase, 60Hz, 4160V Delta primary, 480Y/277V secondary, 45kV BIL - (170) (234) 750 1586 2393 4837 N/A

10 1500 kVA, 150 **°** C, three

- phase, 60Hz, 4160V primary, 480Y/277V secondary, 45kV BIL - (327) 1538 6326 13392 16858 22374 N/A

11 300 kVA, 150 **°** C, three

- phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL - (88) 1176 2592 2723 4517 8378 N/A

12 1500 kVA, 150 **°** C, three

- phase, 60Hz, 12470V primary, 480Y/277V secondary, 95kV BIL - 468 2915 7820 10430 13254 19295 26749

13 A 300kVA, 150  ̊C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL - (344) 392 (731) 488 7113 13187 N/A

13B 2000kVA, 150  ̊C, three

- phase, 60Hz, 24940V primary, 480Y/277V secondary, 125kV BIL - 1073 4420 11564 22162 29706 N/A N/A5- 58 5.5.3 Bus Lead and Bus Loss Correction

DOE received comment during negotiations that substation-style designs common to the medium-voltage, dry- type transformer market are larger than the designs that DOE had previously modeled and experience correspondingly larger bud and lead losses, which can force a unit to employ larger, more efficient cores and coils to overcome the added loss.

DOE worked with manufacturers to explore the magnitude of this effect and made small upward adjustments to bus and lead losses of all medium-voltage, dry- type design lines

. For each design line, DOE added a constant loss value to account for lead and bus l osses

. This change resulted in slightly lower efficiencies (generally close to .02%) and had the effect of nudging the entire design cloud slightly to the left. Because the cost/efficiency curve is upward -sloping, this has the effect of marginally increasi ng the lowest MSPs for a given efficiency even though no direct cost was added to each unit.

5.6 RESULTS OF THE ANALY SIS ON EACH DESIGN LINE

This section provides a visual representation of the results of the engineering analysis. The scatter plots in this sec tion show the relationship between the manufacturer’s selling price and efficiency for each of the 14 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 parameters generated by the design software.

5.6.1 Traditional Core Design s 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. In addition to the results provided 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). For each of the 14 representative units DOE presents the results with the 2010 and 2011 steel price scenari os.

Figure 5.6.1 and Figure 5.6.2 present plots of the manufacturer selling p rices and efficiency levels for the full database of designs for the representative unit from DL1, a 50kVA single -phase, liquid- immersed, pad -mounted 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 these scatter plots:

**•** The current standard efficiency level of 99.08 percent is most cost- effectively met by designs using M3 core steel (2011 prices) or ZDMH core steel (2010 prices).

**•** The amorphous metal (SA1) core is the most cost- effective design for any efficiency level above 99.25 percent, and can reach efficiencies of 99.50 percent.5- 59 Figure 5.6.1 Engineering Analysis Results, Design Line 1, 20115- 60 Figure 5.6.2 Engineering Analysis Results, Design Line 1, 2010

Figure 5.6.3 and Figure 5.6.4 present plots of the manufacturer sales prices and efficiencylevels for the full database of designs for the representative unit from DL2, a 25kVA singlephase, liquid- immersed, pole -mounted 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 most cost- effectively by designs using M2 core steel (2011 and 2010).

**•** The amorphous metal (SA1) core is the most cost- effective design for any efficiency level above 99.10 p ercent, and can reach efficiencies up to 99.5 percent.5- 61 Figure 5.6.3 Engineering Analysis Results, Design Line 2, 20115- 62 Figure 5.6.4 Engineering Analysis Results, Design Line 2, 2010

Figure 5.6.5 and Figure 5.6.6 present plots of the manufacturer sales prices and efficiencylevels for the full database of designs for the representative unit from DL3, a 500kVA singlephase, liquid- immersed distribution transformer with radiators . 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 9.42 percent is most cost- effectively met by designs using M3 core steel (2010) or ZDMH core steel (2011).

**•** 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. 73 percent.5- 63 Figure 5.6.5 Engineering Analysis Results, Design Line 3, 20115- 64 Figure 5.6.6 Engineering Analysis Results, Design Line 3, 2010

Figure 5.6.7 and Figure 5.6.8 present plots of the manufacturer sales prices and efficiencylevels for the full database of designs for the representative unit from DL4, a 150kVA threephase, liquid- immersed distribution transformer . The efficiency levels shown in this plot represent transformers at 50 percent of nameplate load and are corrected for temperature . The fo llowing observations can be made about this scatter plot:

**•** The current standard efficiency level of 99.08 percent is most cost- effectively met by designs using M3 core steel (2011) or ZDMH core steel (2010).

**•** The amorphous metal (SA1) core is the most cost- effective design for any efficiency 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- 65 Figure 5.6.7 Engineering Analysis Results, Design Line 4, 20115- 66 Figure 5.6.8 Engineering Analysis Results, Design Line 4, 2010

Figure 5.6.9 and Figure 5.6.10 presen t plots 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 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 99.42 percent is most cost- effectively met by designs using M3 core steel (2011) or ZDMH (2010).

**•** 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- 67 Figure 5.6.9 Engineering Analysis Results, Design Line 5, 20115- 68 Figure 5.6.10 Engineering Analysis Results, Design Line 5, 2010

Figure 5.6.11 and Figure 5.6.12 present plots 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 distrib ution 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 98.00 percent is most cost- effectively met by designs using M5 core steel (2011 and 2010).

**•** 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 5.6.11 Engineering Analysis Results, Design Line 6, 20115- 70 Figure 5.6.12 Engineering Analysis Results, Design Line 6, 2010

Figure 5.6.13 and Figure 5.6.14 presen t plots of the manufacturer sales prices and efficiency levels for the full d atabase 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 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 98.00 percent is most cost- effectively met by designs using M12 core steel (2011 and 2010).

**•** 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 98.93 percent, and can reach efficiencies up to 99.40 percent.5- 71 Figure 5.6.13 Engineering Analysis Results, Design Line 7, 20115- 72 Figure 5.6.14 Engineering Analysis Results, Design Line 7, 2010

Figure 5.6.15 and Figure 5.6.16 present plots of the manufacturer sales prices and efficiency levels for the full d atabase 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 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 98.60 percent is most cost- effectively met by designs using M5 core steel (2011) or M6 core steel (2010).

**•** The NEMA Premium efficiency level of 99.0 2 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 percent.5- 73 Figure 5.6.15 Engineering Analysis Results, Design Line 8, 20115- 74 Figure 5.6.16 Engineering Analysis Results, Design Line 8, 2010

Figure 5.6.17 and Figure 5.6.18 present plots 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 tran sformer 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 lev el of 98.82 percent is met by designs using M 3 core steel (2011 and 2010).

**•** The five -legged amorphous metal (SA1) 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- 75 Figure 5.6.17 Engineering Analysis Results, Design Line 9, 20115- 76 Figure 5.6.18 Engineering Analysis Results, Design Line 9, 2010

Figure 5.6.19 and Figure 5.6.20 present plots 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 tr ansformer 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 l evel of 99.22 percent is most cost- effectively met by designs using M4 core steel (2011 and 2010).

**•** The amorphous metal (SA1) core is the most cost- effective design for any efficiency level above 99.50 percent, and can reach efficiencies up to 99.67 percen t.5- 77 Figure 5.6.19 Engineering Analysis Results, Design Line 10, 20115- 78 Figure 5.6.20 Engineering Analysis Results, Design Line 10, 2010

Figure 5.6.21 and Figure 5.6.22 present plots 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 transformer with a 95kV BIL. The efficiency levels shown in this plot represent t ransformers 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 most cost- effectively met by designs using M3 core steel (2011) or H0 core steel (2010).

**•** 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- 79 Figure 5.6.21 Engineering Analysis Results, Design Line 11, 20115- 80 Figure 5.6.22 Engineering Analysis Results, Design Line 11, 2010

Figure 5.6.23 and Figure 5.6.24 present plots 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 most cost- effectively met by designs using M5 core steel (2011 and 2010).

**•** The amorphou s 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- 81 Figure 5.6.23 Engineering Analysis Results, Design Line 12, 20115- 82 Figure 5.6.24 Engineering Analysis Results, Design Line 12, 2010

Figure 5.6.25 and Figure 5.6.26 present plots of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit f rom DL13A , 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 mad e about this scatter plot:

**•** The current standard efficiency level of 98.63 percent is most cost- effectively met by designs using M4 core steel (2011 and 2010).

**•** 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- 83 Figure 5.6.25 Engineering Analysis Results, Design Line 13A, 20115- 84 Figure 5.6.26 Engineering Analysis Results, Design Line 13A, 2010

Figure 5.6.27 and Figure 5.6.28 present plots of the manufacturer sales prices and efficiency levels for the full database of designs for the representative unit from DL13 B , a 2000kVA 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 99.15 percent is most cost- effectively met by designs using M3 core steel (2011) or M4 core steel (2010).

**•** The amorphous metal (SA1) core is the most cost- effective design for any efficiency level above 99.43 percent, and can reach efficiencies up to 99.58 percent.5- 85 Figure 5.6.27 Engineering Analysis Results, Design Line 13B, 20115- 86 Figure 5.6.28 Engineering Analysis Results, Design Line 13B, 2010

5.6.2 Symmetric Core Designs

In the preliminary analysis, DOE generated cost

- efficiency relationships for symmetric core design transformers by adjusting comparable traditional core design models. To do this, DOE reduced core losses and core weight while increasing labor costs to approximate the symmetric core d esigns . DOE based these approximations on conversations with manufacturers, and published literature. In the preliminary analysis, DOE requested information and data regarding symmetric core designs. However, DOE was unable to obtain sufficient data to mor e accurately approximate the cost and efficiency of symmetric core designs . Without further information, DOE did not consider symmetric core designs for the NOPR analysis, although it has not screened these designs out of the rulemaking. DOE welcomes comme nt and submission of engineering data that would be useful in analyzing symmetric core designs for the final rule.

5.7 THREE EXAMPLE DESIGNS AND COST 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 selected5- 87 representative units, DOE contracted Optimized Program Service (OPS), a software company specializing in transformer design since 1969. Using a range of input parameters and mat erial 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 core 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 typ ical 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 presented in this section. As these designs illustrate, the software output is used to create a bi ll 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 engin eering analysis.

The three distribution transformers presented are from design lines 1, 7, and 12. Across all the design lines, the complete database of designs contains 39,618 distribution transformer specification and winding sheets, bills of materials, and performance reports. Any infeasible designs or designs below the minimum efficiency standard are removed and then this design database is used 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. M2 core steel with copper primary and aluminum secondary windings (M2CuAl) at a $3.00 A and a $1.20 B evaluation formula.

**•** Design Line 7 : 75 kVA three-phase, low- voltage dry -type. M6 full- mitered cor e steel with aluminum primary and secondary windings (M6AlAl) at a $0.50 A and a $0.10 B evaluation formula.

**•** Design Line 12 : 1500 kVA three-phase, medium-voltage dry-type. M3 step- lap core steel with aluminum primary and secondary windings (M3AlAl) at a $1.50 A and a $0.30 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. This design incorporates M2 core steel, with a copper primary and an aluminum secondary. The evaluation factors for this desi gn are $3.00 A and $1.20 B. The bill of materials and associated breakdown of costs for this design are also reported, after the design and electrical analysis reports.5- 885- 89 Table 5.35 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 fixed5- 90 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.

Table 5.35 Bill of Materials for Transformer from Design Line 1

* 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. $ Each $ Total

$2.00 $430.42 $4.84 $261.14 $2.08 $49.64

$1.52 $6.94

$3.35 $125.93 $140.34 $140.34 $25.00 $25.00 $0.65 $0.65 $58.00 $58.00 $16.00 $16.00 $7.48 $1,122

$ Total $25.76 $5.15 $15.46 $5.15 $7.73 $25.76 $18.03 $9.79 $23.18 $34.52 $12.88 $11.22 $194.65

$1,316

$140 $210 $364

$2,031 B$ Input $1.20 Efficiency at 99.00% Bill of Materials and Labor for liquid-immersed, single-phase, pad-mount, 50kVA

A$ Input $3.00

Primary Copper wire, formvar, round 53.93 Secondary windings* (lb) Aluminum strip, thickness range 0.02-0.045 23.83 Material Item Type Quantity Core Steel* (lb) M2-.007 215.75

Tank

- 1 Core clamp

- 1 Winding form & insulation* (lb) Kraft insulating paper with diamond adhesive 4.34

Oil (gal)

- 37.6

Misc. hardware

- 1 Scrap Factor 1.00%
Total Material Cost Nameplate

- 1 Bushings HV & LV 1

Labor item Hours Rate Lead dressing 0.5 51.52 Total Material Weight (lb) 748

Tanking and impregnating 0.3 51.52 Preliminary test 0.1 51.52 Inspection 0.1 51.52

Marking and miscellaneous 0.35 51.52 Winding the primary 0.19 51.52 Final test 0.15 51.52 Pallet loading 0.5 51.52

Core assembly 0.25 51.52 Handling and slitting factor (on material) 1.50%
Total Labor 3.56 51.52 Winding the secondary 0.45 51.52 Cutting, forming, and annealing 0.67 51.52

Manufacturer Selling Price** Shipping Cost (Based on Total Weight) $0.22/lb Non-production Cost Markup 25.00% Manufacturing Cost (Material + Labor) Factory Overhead (Materials only) 12.50%5- 91 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 57 percent of the final manufacturer selling price is direct materi al and scrap. Labor accounts for 9 percent of the price, factory overhead accounts for 7 percent, and together, shipping and non-production costs account for 27 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 design line 7. This is a 75kVA, three-phase, low-voltage, dry-type unit. The design shown here is for M6 full- mitered core steel with aluminum primary and secondary windings, and a $0.50A and $0.10B. Core/Coils 44%

Non

- Production 18% Shipping 9% Factory Overhead 7% Labor 9% Other Material 13%5- 925- 93 Table 5.36 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.5- 94 Table 5.36 Bill of Materials for Transformer from Design Line 7

* 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. $ Each $ Total

$1.46 $438.44 $2.97 $162.33

$2.97 $91.88

$24.50 $36.83

$131.82 $131.82 $19.00 $19.00 $0.32 $7.54

$0.65 $0.65 $1.50 $10.50 $9.00 $27.00 $22.55 $26.53 $7.00 $7.00 $7.29 $967

$ Total $12.88 $2.58 $2.58 $5.15 $10.30 $10.30 $77.28 $30.40 $52.55 $69.55 $51.52 $10.94

$336

$1,303

$121 $141 $356

$1,921 Bill of Materials and Labor for low-voltage, dry-type, three-phase, 75kVA

A$ Input $0.50

Material Item Type Quantity Core Steel* (lb) M6-.014 301.33 B$ Input $0.10 Efficiency at 98.12%

Winding form & insulation* (lb) Nomex insulation 0.21

Enclosure 14-gauge steel 1 Primary winding* (lb) Aluminum wire, rectangular, 0.1x0.2, Nomex 54.6

Secondary windings* (lb) Aluminum wire, rectangular, 0.1x0.2, Nomex 30.9

Nameplate

- 1 LV Buss Bar (ft.)

- 7 Core clamp

- 1 Duct spacers (ft., drop 2/3) - 23.56

Misc. hardware

- 1 Scrap Factor 1.00%
Total Material Cost HV Terminal

- 3 Impregnation

- 1.18

Labor item Hours Rate Lead dressing 0.25 51.52 Total Material Weight (lb) 502

Final test 0.1 51.52 Packing 0.2 51.52 Inspection 0.05 51.52 Preliminary test 0.05 51.52

Winding the primary 0.59 51.52 Winding the secondary 1.02 51.52 Marking and miscellaneous 0.2 51.52 Enclosure manufacturing 1.5 51.52

Handling and slitting factor (on material) 1.50%
Total Labor 6.31 51.52 Core stacking 1.35 51.52 Core assembly 1 51.52

Non-production Cost Markup 25.00%

Manufacturer Selling Price** Manufacturing Cost (Material + Labor) Factory Overhead (Materials only) 12.50% Shipping Cost (Based on Total Weight) $0.22/lb5- 95 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 pe rcent 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 tostudy the representative unit from design line 12. This is a 1500kVA, three-phase, mediumvoltage, dry-type unit at 95kV BIL. The design shown here is for M3 step- lap mitered core steel with aluminum primary and secondary windings, and a $1.50A and $0.30B. This is a different design option comb ination than the original design selected for the preliminary analysis, which was for M4 core steel with copper primary and aluminum secondary windings, and a $1.50A and $0.30B. Core/Coils 36%

Non

- Production 19% Shipping 7% Factory Overhead 6% Labor 18% Other Material 14%5- 965- 975- 98 Table 5.37 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 tra nsformer. These materials are then marked

- up at the bottom of the table to arrive at the manufacturer’s selling price.5- 99 Table 5.37 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 scrap on core due to mitering process. *** Price based on rounded estimations. The non-rounded price may vary slightly. $ Each $ Total

$1.88 $10,760 $2.97 $1,851

$2.08 $755

$24.50 $4,153

$820.43 $820 $125.00 $125

$0.56 $890 $0.65 $0.65 $12.00 $192 $9.00 $27 $135.00 $135 $12.34 $1,186 $22.55 $742 $54.00 $54 $606 $22,296

$ Total $52 $13 $26 $39 $103 $113 $412 $1,461

$185 $311 $309 $263 $3,286

$25,582 $2,787 $2,265 $7,092

$37,727 Manufacturer Selling Price*** Shipping Cost (Based on Total Weight) $0.22/lb Non-production Cost Markup 25.00% Manufacturing Cost (Material + Labor) Factory Overhead (Materials only) 12.50% Core assembly 6 51.52 Handling and slitting factor (on material) 1.50%
Total Labor 58.7 51.52 Winding the secondary 3.6 51.52 Core stacking 6.04 51.52 Enclosure manufacturing 8 51.52 Winding the primary 28.35 51.52 Packing 2 51.52 Marking and miscellaneous 2.2 51.52 Preliminary test 0.5 51.52
Final test 0.75 51.52 Lead dressing 1 51.52 Inspection 0.25 51.52 Labor item Hours Rate Total Material Cost Total Material Weight (lb) 8,055 Misc. hardware

- 1 Scrap Factor 1.00% Winding combs

- 96.11 Impregnation

- 32.89 HV tap board

- 3
HV Terminals

- 1 Nameplate

- 1 LV Buss Bar (ft.)

- 16 Core clamp

- 1 Duct spacers

- 1,589.03 Winding form & insulation* (lb) Nomex insulation 134

Enclosure 12-gauge steel 1 Primary winding* (lb) Copper wire, rectangular, 0.1x0.2, Nomex 622.58

Secondary windings* (lb) Aluminum strip, thickness range 0.02 - 0.045 362.33 Material Item Type Quantity Core Steel* (lb) M4-.011 5,738.61 B$ Input $0.30 Efficiency at 99.14% Bill of Materials and Labor for medium-voltage, dry-type, three-phase, 1500kVA

A$ Input $1.505- 100 Fig ure 5.7.3 Manufacturer Selling Price Breakdown, Transformer from Design Line 12 provides a summary of the costs contributing to the total selling price of the transformer from design line 12. For this design, approximately 59 percent of the final manufacturer selling price is direct material and scrap. Labor accounts for 9 percent of the price, factory overhead accounts for 7 percent, and together, shipping 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%