5-i 

CHAPTER 5. ENGINEERING ANALYSIS 

TABLE OF CONTENTS 

5.1 INTRODUCTION .............................................................................................................. 1 

5.2 EQUIPMENT CLASSES AND BASELINE MOTORS ANALYZED............................. 2 

5.2.1 Equipment Classes Analyzed.................................................................................. 2 

5.2.2 Baseline Motors Analyzed...................................................................................... 4 

5.3 ENGINEERING ANALYSIS METHODOLOGY............................................................. 5 

5.3.1 Manufacturer Interview Guide Approach............................................................... 5 

5.3.2 Subcontractor Software Design Approach.............................................................. 6 

5.4 COST MODEL ................................................................................................................... 8 

5.4.1 Constructing a Bill of Materials.............................................................................. 9 

5.4.2 Labor Costs and Assumptions .............................................................................. 10 

5.4.3 Manufacturer Markups.......................................................................................... 11 

5.5 RESULTS OF ENGINEERING ANALYSIS .................................................................. 12 

5.5.1 Polyphase, 1 Horsepower, 4-Pole, 56-Frame Motor............................................. 12 

5.5.2 Capacitor-Start, Induction-Run, 1/2 Horsepower, 4-Pole, 56-Frame Motor ........ 16 

5.5.3 Capacitor-Start, Induction-Run, 1/2 Horsepower, 4-Pole, 48-Frame Motor ........ 18 

5.5.4 Capacitor-Start, Capacitor-Run, 3/4 Horsepower, 4-Pole, 56-Frame Motor........ 21 

5.6 SCALING RELATIONSHIPS ......................................................................................... 24 

5.6.1 Interpolation of Cost-Efficiency Points ................................................................ 24 

5.6.2 Motor Losses......................................................................................................... 26 

5.6.3 Candidate Standard Levels ................................................................................... 27 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-ii 

LIST OF TABLES 

Table 5.2.1 Polyphase Small Electric Motor Equipment Classes.............................................. 2 

Table 5.2.2 Capacitor-Start, Induction-Run Small Electric Motor Equipment Classes ............ 3 

Table 5.2.3 Capacitor-Start, Capacitor-Run Small Electric Motor Equipment Classes ............ 3 

Table 5.2.4 Design Characteristics of the Four Baseline Motors Analyzed .............................. 4 

Table 5.2.5 Efficiency Ratings of Baseline Motors Selected for Analysis................................ 5 

Table 5.3.1 National Electrical Manufacturers Association Manufacturer Consensus on 

Efficiency Levels for Equipment Classes Analyzed....................................................................... 6 

Table 5.4.1 Labor Markups for Small Electric Motor Manufacturers ..................................... 10 

Table 5.5.1. Efficiency and MSP Data for Polyphase Motor ................................................... 14 

Table 5.5.2. Polyphase, 1 Horsepower, 4-Pole, 56-Frame Motor Designs............................... 15 

Table 5.5.3. Efficiency and MSP Data for Capacitor-Start, Induction-Run, 56-Frame Motor. 17 

Table 5.5.4. Capacitor-Start, Induction-Run, 1/2 Horsepower, 4-Pole, 56-Frame Motor 

Designs 18 

Table 5.5.5. Efficiency and MSP Data for Capacitor-Start, Induction-Run, 48-Frame Motor. 20 

Table 5.5.6. Capacitor-Start, Induction-Run, 1/2 Horsepower, 4-Pole, 48-Frame Motor 

Designs 21 

Table 5.5.7. Efficiency and MSP Data for Capacitor-Start, Capacitor-Run Motor.................. 23 

Table 5.5.8. Capacitor-Start, Capacitor-Run, 3/4 Horsepower, 4-Pole, 56-Frame Motor........ 24 

Table 5.6.1 Candidate Standard Levels for Equipment Classes Analyzed.............................. 28 

Table 5.6.2 Matrix of K Values used for Scaling Candidate Standard Levels ........................ 30 

Table 5.6.3 Candidate Standard Level 1 for Polyphase Small Electric Motors....................... 30 

Table 5.6.4 Candidate Standard Level 1 for Capacitor-Start, Induction-Run Small Electric 

Motors 31 

Table 5.6.5 Candidate Standard Level 1 for Capacitor-Start, Capacitor-Run Small Electric 

Motors 31 

LIST OF FIGURES 

Figure 5.4.1 Standard Method of Cost Accounting for Standards Rulemaking.......................... 8 

Figure 5.5.1. Polyphase 1 Horsepower, 4-Pole, 56-Frame Motor Engineering Analysis, with 

Maximum Technology Point ........................................................................................................ 13 

Figure 5.5.2. Polyphase 1 Horsepower, 4-Pole, 56-Frame Motor Engineering Analysis, 

without Maximum Technology Point ........................................................................................... 14 

Figure 5.5.3. Capacitor-Start, Induction-Run, 1⁄2 Horsepower, 4-Pole, 56-Frame Engineering 

Analysis Curve, with Maximum Technology Point ..................................................................... 16 

Figure 5.5.4. Capacitor-Start, Induction-Run, 1⁄2 Horsepower, 4-Pole, 56-Frame Engineering 

Analysis Curve, without Maximum Technology Point ................................................................ 17 

Figure 5.5.5. Capacitor-Start, Induction-Run, 1⁄2 Horsepower, 4-Pole, 48-Frame Engineering 

Analysis Curve, with Maximum Technology Point ..................................................................... 19 

Figure 5.5.6. Capacitor-Start, Induction-Run, 1⁄2 Horsepower, 4-Pole, 48-Frame Engineering 

Analysis Curve, without Maximum Technology Point ................................................................ 20 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-iii 

Figure 5.5.7. Capacitor-Start, Capacitor-Run 3⁄4 Horsepower, 4-Pole, 56-Frame Engineering 

Analysis Curve, with Maximum Technology Point ..................................................................... 22 

Figure 5.5.8. Capacitor-Start, Capacitor-Run 3⁄4 Horsepower, 4-Pole, 56-Frame Engineering 

Analysis Curve, without Maximum Technology Point ................................................................ 23 

Figure 5.6.1 Polyphase Motor Designs with Interpolated Curve Fits....................................... 25 

Figure 5.6.2 Function of Delta with Horsepower for 1-200 Horsepower,Energy Independence 

and Security Act of 2007 Efficiency Standards............................................................................ 27 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-iv 

LIST OF ACRONYMS AND ABBREVIATIONS 

AWG American wire gauge 

BOM Bill of materials 

CSCR Capacitor-Start, Capacitor-Run Motor 

CSIR Capacitor-Start, Induction-Run Motor 

DOE United States Department of Energy 

EISA Energy Independence and Securities Act 

M* M15, M19, M36, M47, M56 - grade of core steel 

MSP Manufacturer Selling Price 

NEMA National Electrical Manufacturers Association 

NCI Navigant Consulting, Inc 

RPM Revolutions per minute 

TSD Technical Support Document 

SEC Securities and Exchange Commission 

U.S. United States 

μF Microfarads 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-1 

CHAPTER 5. ENGINEERING ANALYSIS 

5.1 INTRODUCTION 

The engineering analysis estimates the increase in manufacturer selling price (MSP) 

associated with technological and design changes that improve the efficiency of small electric 

motors. This chapter presents the U.S. Department of Energy’s (DOE’s) assumptions, 

methodology and findings for the small electric motor engineering analysis. The output from the 

engineering analysis is a “cost-efficiency” relationship for each motor analyzed which describes 

how cost changes as efficiency increases. The engineering analysis is used as an input to the lifecycle cost analysis (see preliminary Technical Support Document (TSD) chapter 8) as well as the 

national impact analysis (see preliminary TSD chapter 10). 

As discussed in chapter 3 of this preliminary TSD, the electric motors covered in this 

rulemaking include general-purpose capacitor-start, induction-run (CSIR), capacitor-start, 

capacitor-run (CSCR), and polyphase electric motors built in a National Electrical Manufacturers 

Association (NEMA) two-digit frame size. The engineering analysis selected and analyzed one 

small electric motor from each of these three categories of covered motors. 

The engineering analysis takes input from the market and technology assessment (see 

preliminary TSD chapter 3) and the screening analysis (see preliminary TSD chapter 4). These 

inputs include equipment classes, baseline motor performance, methods for improving 

efficiency, and design options that have passed the screening criteria. The engineering analysis 

uses these inputs, coupled with material price estimates, design parameters, and other 

manufacturer inputs, to develop the relationship between the MSP and nominal full-load 

efficiency of the representative motors studied. For small electric motors, this relationship was 

evaluated using third-party design software, created and maintained by Yeadon Energy Systems, 

Inc. 

At its most basic level, the output of the engineering analysis is a curve that estimates the 

manufacturer’s selling price for a range of efficiency values. This output is subsequently markedup to determine the end-user prices based on the various distribution channels (see preliminary 

TSD chapter 6). After determining customer prices by applying distribution chain markups, sales 

tax, and contractor markups, the data is combined with the energy-use and end-use load 

characterization (see preliminary TSD chapter 7) and used as a critical input to the customer’s 

life-cycle cost and payback period analysis (see preliminary TSD chapter 8). 

The results presented in this chapter do not provide a full assessment of the 

manufacturer’s costs associated with increasing efficiency levels for a small electric motor. The 

relationship presented in this chapter assumes an ideal situation, where manufacturers do not 

incur any costs associated with retooling, product redesign, training, or marketing associated 

with incorporating design changes to their product lines to achieve the efficiency levels 

presented. In the notice of proposed rulemaking stage of the rulemaking, DOE will attempt to 

quantify the additional costs manufacturers would incur when complying with mandatory 

efficiency standards. For a discussion of these costs and DOE’s methodology for quantifying 

them, see preliminary TSD chapter 12, the preliminary manufacturer impact analysis. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-2 

In this chapter, DOE discusses the equipment classes analyzed and the representative 

motors selected from all covered small electric motors. DOE also presents the methodology, 

inputs, and results associated with the development of MSP versus efficiency curves for each of 

the representative motors. Finally, DOE discusses the approach used to scale the engineering 

analysis to all other equipment classes for the national impact analysis. 

5.2 EQUIPMENT CLASSES AND BASELINE MOTORS ANALYZED 

 Due to the large number of equipment classes, DOE did not directly analyze all covered 

motors. Instead, DOE selected certain equipment classes to analyze after reviewing the motors 

studied in the small electric motors determination analysis and examining manufacturers’ catalog 

data. 

5.2.1 Equipment Classes Analyzed 

 When identifying which motors to evaluate, the highest priority in selecting equipment 

classes was ensuring that each of the three motor categories was represented. DOE selected one 

model from each of the motor categories (i.e., polyphase, CSIR, and CSCR) in order to minimize 

any error that might be introduced scaling across motor categories when extrapolating findings to 

other horsepower (hp) ratings and pole configurations. DOE then scaled from those three 

representative model motors to all equipment classes covered in this rulemaking. 

 Table 5.2.1 through Table 5.2.3.present the 72 equipment classes (EC) for polyphase, 

CSIR and CSCR motors, broken down by number of poles and horsepower/standard kilowatt 

equivalent ratings. Should DOE establish minimum energy conservation standards for small 

electric motors, each “EC” cell in the following table would be replaced by the applicable 

nominal full load efficiency value. 

Table 5.2.1 Polyphase Small Electric Motor Equipment Classes 

Horsepower/Standard 

Kilowatt Equivalent 

Six Poles Four Poles Two Poles 

1/4 hp/0.18 kW EC #1 EC #2 EC #3 

1/3 hp/0.25 kW EC #4 EC #5 EC #6 

1/2 hp/0.37 kW EC #7 EC #8 EC #9 

3/4 hp/0.55 kW EC #10 EC #11 EC #12 

1 hp/0.75 kW EC #13 EC #14 EC #15 

11⁄2 hp/1.1 kW EC #16 EC #17 EC #18 

2 hp/1.5 kW EC #19 EC #20 EC #21 

≥ 3 hp/2.2 kW EC #22 EC #23 EC #24 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-3 

Table 5.2.2 Capacitor-Start, Induction-Run Small Electric Motor Equipment Classes 

Horsepower/Standard 

Kilowatt Equivalent 

Six Poles Four Poles Two Poles 

1/4 hp/0.18 kW EC #25 EC #26 EC #27 

1/3 hp/0.25 kW EC #28 EC #29 EC #30 

1/2 hp/0.37 kW EC #31 EC #32 EC #33 

3/4 hp/0.55 kW EC #34 EC #35 EC #36 

1 hp/0.75 kW EC #37 EC #38 EC #39 

11⁄2 hp/1.1 kW EC #40 EC #41 EC #42 

2 hp/1.5 kW EC #43 EC #44 EC #45 

≥ 3 hp/2.2 kW EC #46 EC #47 EC #48 

Table 5.2.3 Capacitor-Start, Capacitor-Run Small Electric Motor Equipment Classes 

Horsepower/Standard 

Kilowatt Equivalent 

Six Poles Four Poles Two Poles 

1/4 hp/0.18 kW EC #49 EC #50 EC #51 

1/3 hp/0.25 kW EC #52 EC #53 EC #54 

1/2 hp/0.37 kW EC #55 EC #56 EC #57 

3/4 hp/0.55 kW EC #58 EC #59 EC #60 

1 hp/0.75 kW EC #61 EC #62 EC #63 

11⁄2 hp/1.1 kW EC #64 EC #65 EC #66 

2 hp/1.5 kW EC #67 EC #68 EC #69 

≥ 3 hp/2.2 kW EC #70 EC #71 EC #72 

 The next step DOE took in selecting representative equipment classes for the engineering 

analysis was to choose a range of horsepower ratings. Motors with different horsepower ratings 

have different cost-efficiency characteristics just like those of different motor categories (i.e., 

polyphase, CSIR, and CSCR). Therefore, DOE selected a subset of horsepower ratings that were 

representative of popular models and would facilitate scaling to other horsepower ratings not 

analyzed. The horsepower ratings selected for the CSIR and polyphase representative motors 

were the same as those used in DOE’s determination analysis. These ratings were recommended 

by industry for DOE’s determination and are considered high-volume, widely produced models 

produced by small electric motor manufacturers. DOE did not analyze a CSCR motor for the 

determination analysis, therefore, the horsepower rating for the CSCR motor was chosen by 

reviewing popular ratings in various manufacturer catalogs. 

 Finally, for each of the motor categories and horsepower ratings selected, DOE had to 

choose a pole configuration for the representative motors. After reviewing the determination 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-4 

analysis and manufacturer catalog data, DOE chose four-pole motors, because they appear to 

represent the most popular configuration. 

Table 5.2.4 presents the major design characteristics of the four representative baseline 

motors that were analyzed by DOE and participating NEMA manufacturers. 

Table 5.2.4 Design Characteristics of the Four Baseline Motors Analyzed 

Motor Category Horsepower Number of Poles Frame Size 

Polyphase 1.00 4 56 

CSIR 1/2 4 48 

CSIR* 1/2 4 56 

CSCR 3/4 4 56 

* DOE identified these four motors as the representative units to study, and then conducted an engineering analysis 

to study the relationship between motor efficiency and manufacturer selling price. DOE found that there was 

virtually no difference between the 48 and 56 frame sizes for the 1⁄2-horsepower, four-pole CSIR motors. Therefore, 

DOE elected to drop the 56 frame size from its analysis, since frame size tends to scale with horsepower, and at this 

rating it would be more common to find a 48 frame than a 56. 

One observable aspect of the four baseline motors selected is that there are two CSIR 

motors with the same horsepower rating and number of poles. Even though frame size is not a 

parameter DOE uses to differentiate between equipment classes, DOE selected these two motors 

in order to determine if the MSP-efficiency curves would vary across frame size. The 0.5 

horsepower CSIR motor is one that is commonly manufactured in both the 48 and 56 frame 

sizes, therefore this was considered a good unit for analysis. After reviewing the results of the 

engineering analysis on these two frame sizes DOE found that there was no significant difference 

between the 48 and 56 frame size CSIR motors. Due to that similarity, DOE decided to remove 

the 56 frame size CSIR 0.5 horsepower, four-pole motor from its analysis because (1) the 

analytical findings would be redundant with the 48 frame size model and (2) smaller horsepower 

ratings tend to be manufactured in smaller frame sizes. Discussion of the draft findings of this 

representative motor and the rationale behind not continuing to analyze the 56 frame size CSIR 

motor is presented in the results section of this chapter (see section 5.6). 

5.2.2 Baseline Motors Analyzed 

For each representative equipment class selected, DOE identified a specific baseline 

motor as a fundamental design against which it would apply design changes to improve the 

motor’s efficiency. DOE chose the baseline motors to represent the typical characteristics of 

small electric motors in that equipment class. Because there are no existing minimum energy 

conservation standards for small electric motors, the baseline efficiency was selected after 

reviewing efficiency ratings from the determination analysis, manufacturer catalogs, and 

consultation with technical experts. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-5 

Table 5.2.5 Efficiency Ratings of Baseline Motors Selected for Analysis 

Basic Characteristics of Motors Analyzed Baseline Efficiency % 

Polyphase, 1 hp, 4-pole, 56 frame 75.8 

CSIR, 1⁄2 hp, 4-pole, 48 frame 62.3 

CSIR, 1⁄2 hp, 4-pole, 56 frame 63.3 

CSCR, 3⁄4 hp, 4-pole, 56 frame 68.6 

In addition to the efficiency rating, DOE used performance and physical characteristics of 

these small electric motors, such as breakdown torque, locked-rotor torque, and locked-rotor 

current as well as dimensional characteristics of the motor. In making its selections, DOE 

ensured that the baseline motors had performance characteristics falling within the specifications 

of general-purpose motors as defined in NEMA MG 1-1987. Specific detail on these baseline 

motors is provided in the results section of this chapter, section 5.6. 

5.3 ENGINEERING ANALYSIS METHODOLOGY 

DOE employed a two-fold approach in conducting the engineering analysis. First, DOE 

prepared and circulated an interview guide to small electric motor manufacturers requesting 

detail on their costs and design options at certain efficiency levels. Second, DOE engaged a 

third-party software design company which specializes in small electric motor designs to prepare 

four sets of designs, each spanning a range of efficiency levels. Both the manufacturers and the 

third-party software design company were given the fundamentals of the representative models 

from which to start. 

DOE decided to conduct the engineering analysis using this two-pronged approach in 

order to best develop practical, manufacturer-derived engineering curves that reflect the 

relationship between manufacturer selling price and efficiency. The small electric motor designs 

prepared by the third-party software design company would then be used by DOE to verify and 

corroborate the manufacturer-supplied curves. 

5.3.1 Manufacturer Interview Guide Approach 

 DOE prepared and circulated a manufacturer interview guide that requested information 

on design options and costs associated with the four representative units selected for analysis 

(see TSD Appendix 12A.2 Part A). Due to the fact that DOE is not aware of any United States 

(U.S.) manufacturers of small electric motors who are not NEMA members, this interview guide 

was only circulated to manufacturers who were, at the time, NEMA members. 

 For consistency of reporting the designs, NEMA’s electric motors technical committee 

developed and recommended four efficiency levels that DOE should include in the interview 

guide, a baseline design level, an EPACT level, a NEMA Premium level, and a maximum 

technologically achievable level. This fourth level did not include a specific efficiency value, but 

was left open to manufacturers who would employ different approaches to achieving the 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-6 

maximum technologically achievable level. The efficiency levels recommended by NEMA are 

shown in Table 5.3.1 below. These levels are the ones used in the manufacturer interview guide, 

however DOE later refined the baseline model selection for the engineering analysis, which 

accounts for the difference between the baseline efficiency values presented in this table and in 

Table 5.2.5. 

Table 5.3.1 National Electrical Manufacturers Association Manufacturer Consensus on 

Efficiency Levels for Equipment Classes Analyzed 

Equipment Class Baseline EPACT NEMA 

Premium Max Tech 

Polyphase, 1 hp, 4-pole, 56 frame 74.0 % 78.5 % 85.5 % TBD 

CSIR, 1⁄2 hp, 4-pole, 48 frame 59.0 % 68.0 % 73.0 % TBD 

CSIR, 1⁄2 hp, 4-pole, 56 frame 61.5 % 68.0 % 75.5 % TBD 

CSCR, 3⁄4 hp, 4-pole, 56 frame 66.0 % 77.0 % 80.0 % TBD 

 DOE issued the manufacturer interview guide incorporating these efficiency levels and 

requesting a max-tech efficiency design (at an undetermined efficiency level) for each of the four 

motor types. Manufacturers were given four months to prepare their responses and submit them 

to DOE’s contractor under a confidentiality agreement. 

5.3.2 Subcontractor Software Design Approach 

 Concurrent with the manufacturer-based engineering analysis, DOE worked with a 

subcontractor to develop MSP-efficiency curves for the same four representative electric motors. 

As discussed above, DOE retained a small electric motor experta

 with design experience and 

software, who prepared a set of designs with increasing efficiency. The contractor started with 

similar baseline model motors used by the manufacturers and modified the designs to improve 

the efficiency. As new designs were created, careful attention was paid to the critical 

performance characteristics to ensure that the resulting small electric motor designs had similar 

performance characteristics to the baseline motor and were manufacturable. To this end, DOE 

established a set of design limitations that are applied uniformly across all four sets of designs to 

ensure that the resulting designs are reasonable and manufacturable. The following list presents 

the design limitations: 

• Peak slot fill – the maximum value this parameter should reach is 75 percent for an 

assumed high volume simultaneous insertion process. (Note: DOE considers “slot fill” 

to be the area of the wire (including insulation) divided by the total slot area available for 

winding.) 

• Air gap between rotor and stator – the air gap between the rotor and stator should not be 

less than 0.010 inches. Having air gaps tighter than this minimum could be problematic 

 

a

 Yeadon Energy Systems, Inc. (YES) of Iron Mountain, Michigan. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-7 

and may cause contact between the spinning rotor and the stator, especially as shaft 

length increases. 

• Stator slot opening – the opening in combination with the copper wire gauges used 

should graph to a point in the “Level Wind Area” of the “Blade Gap Chart” taken from 

Alliance Winding1. Without this restriction, DOE is concerned there may be too many 

issues with wire breakage and jamming of manufacturers’ winding tools. 

• Stack height – the stack height (or length) may change by up to 100 percent relative to 

the baseline height (i.e., the stack height may double the original value). This design 

option enables motors to regain induction when steel grades are improved. 

• Locked rotor torque – the torque must be kept within 10 percent of the baseline motor, 

and be within the specifications set forth by NEMA MG 1-1987 in Section 12.32.2. (e.g., 

for a 0.5 hp, four-pole motor the minimum is 85 oz-ft., [7.2 Newton meters]). 

Maintaining the locked rotor torque within 10 percent of the baseline motor will help 

preserve the utility of the more efficient motor designs. 

• Locked rotor current – the current should not exceed the values of NEMA MG 1-1987 

Section 12.33.2 (Design N) (e.g., 45 amperes for a 115-volt, 0.5 hp motor). . 

• Breakdown torque – the breakdown torque must fall within NEMA MG 1-1987 Table 10-

5 limits for all ratings (e.g., for 0.5 hp, four-pole small electric motor greater than 40.5 

oz-ft, but not to exceed 58.0 oz-ft [3.43-4.91 Newton meters]). 

• Cooling system – the parameters directly related to the motor’s cooling system, such as 

ventilation openings in the laminations, should not be modified in a manner that will 

increase the operating temperature of the motor. 

• Rotor skew – the rotor skew may be altered, but it cannot be raised or lowered to a point 

that will introduce harmonics that adversely affect motor performance or introduce cusps 

in the acceleration curve. (Note: this design limitation was subjective and relied on the 

expertise of the designers). 

Working within these parameters, the subcontractor prepared five designs for each 

representative motor that adhered to these requirements while improving the efficiency of the 

motors. The design levels prepared were at the baseline, an energy efficient level, a premium 

efficient level, a premium plus efficient level and a maximum technologically achievable level. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-8 

5.4 COST MODEL 

 DOE uses a standard method of cost accounting to determine the costs associated with 

manufacturing. This methodology is illustrated in Figure 5.4.1, where production costs and nonproduction costs are combined to determine the full cost of a product. 

Direct

Labor

Direct

Labor Direct

Material

Direct

Material Overhead Overhead Selling Selling General &

Admin. Admin. R & D R & D Interest Interest

Indirect Labor

Full Production Cost 1 Non-Production Cost

Indirect Material

Maintenance

Depreciation

Taxes

Insurance related

to assets

Mkt. research

Advertising

POS promotion

Sales person

salary + travel

+ commission

Logistics

- Warehousing

- Delivery

- Record

 keeping

- Order entry/

 processing

Costs of

service &

staff units

General

corporate

costs

- comp. etc.

Costs

associated

with efforts

to find new

or improved

products or

production

processes

Costs

of

borrowing

funds

1 Tax Reform Act of 1986, essentially, requires companies to measure cost of goods sold as the full production cost of the goods sold.

Full Cost of Product Full Cost of Product

Code

compliance

Modernization

Cust. service

Figure 5.4.1 Standard Method of Cost Accounting for Standards Rulemaking 

 DOE developed estimates of some of the cost multipliers shown in Figure 5.4.1 by 

reviewing Security and Exchange Commission (SEC) SEC-10K reports from A.O. Smith 

Corporation, Baldor Electric Company, Emerson Motor Company, and Regal-Beloit Corporation 

as well as through conversations with industry experts. Together, the full production cost and the 

non-production costs equal the full cost of the product. 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 costs include the cost of selling (market research, 

advertising, sales representatives, logistics), general and administrative costs, research and 

development, interest payments and profit factor (not shown in the figure). 

After the subcontractor designs were completed and verified for manufacturability (i.e., 

following the restrictions mentioned in section 5.3.2), the next step was applying this cost model 

to all of them. A standard bill of materials (BOM) was constructed that calculates direct material 

costs, labor time estimates along with costs and applies various manufacturer markups for nonproduction costs to create a MSP. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-9 

5.4.1 Constructing a Bill of Materials 

The BOM calculated for each design contained three types of material costs: fixed costs, 

variable costs and semi-fixed costs. Fixed cost materials are those parts and components that 

remain constant across all designs within a set. That is, these are the parts that do not vary with 

efficiency, such as switches, ball-bearings and other components. The aggregate fixed cost will 

vary from one motor category to another because the different motor categories use different 

parts (e.g., the representative polyphase motor had a total fixed cost of $11.21, however the total 

fixed costs for CSIR and CSCR motors are different). The variable costs considered are those 

portions of the BOM that vary based on the cost of the material and the amount of that material 

used in the design. For example, stator and rotor lamination costs are variable costs because the 

material price for the different steel grades changes as does the volume of steel needed for each 

design. Finally, semi-fixed costs are those materials that have a constant price per pound, but 

vary in cost from design to design as a function of the amount used in the motor designs. An 

example of this type of cost is the die-cast aluminum or copper used in the rotor bars. The price 

per pound for aluminum or copper is the same from design to design; however, the cost per 

design is different because the amount of metal used for die-casting the rotor bars varies with 

each design. 

DOE presents a detailed bill of materials for one design (i.e., the premium efficiency 

design) from each of the three motor categories analyzed in preliminary TSD appendix 5A. The 

discussion below describes the level of detail contained in the bill of materials presented in this 

appendix. 

Each item in the BOM is organized by the type of cost (i.e., fixed, variable, and semifixed) and the component of the motor to which they apply. For example “end cap assembly” is a 

subheading under the fixed cost portion of the BOM, and under this subheading there are several 

itemized parts with associated costs. The fixed costs portion of the BOM includes the following 

subheadings, each with an itemized parts list: stator assembly, rotor assembly, end cap 

assembly, housing assembly, hardware, and final assembly. The variable cost section of the 

BOM includes subheadings for the stator assembly, rotor assembly, and hardware. The semifixed costs section includes itemized lists dedicated to the stator assembly, rotor assembly, and 

housing assembly. There are some subheadings that appear under both the variable cost and 

semi-fixed cost sections; however these subheadings have different items in their respective lists. 

The subheadings that have an itemized list of components include the stator assembly, 

rotor assembly, end cap assembly, housing assembly, hardware, and final assembly. The stator 

assembly’s itemized lists include prices for cleats, lead wires, capacitor wires (for appropriate 

motor categories), splices, insulation, slot liner, copper shipping, stator laminations, main and 

auxiliary (when applicable) copper wire costs. The rotor assembly portion of the BOM includes 

prices for a fan, bearings, the rotor aluminum or copper, and the lamination costs. The housing 

assembly list includes paint, a fan shroud, a base, and the actual housing costs. Much of the 

hardware costs are fixed and include pricing for washers, capacitor covers (when applicable), 

mounting bolts, cap screws, thermal switch screws, terminal block screws, terminal cover 

screws, studs, conduit cap, a start switch (when applicable), a nameplate, as well as some 

variable costs for start and run capacitors (when applicable). All the lists for the subheadings 

discussed here represent items from the fixed, variable, and semi-fixed cost sections of the BOM. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-10 

5.4.2 Labor Costs and Assumptions 

Due to the degree of automation used in manufacturing small electric motors, labor costs 

are not a significant portion of the overall production cost and do not vary significantly with 

increasingly efficient designs. The modeling software provides an estimate of the amount of 

labor associated with each small electric motor design. DOE then multiplies that estimate by a 

marked up hourly rate to determine the proportion of labor cost associated with the 

manufacturer’s production cost. 

DOE used the same hourly labor rate for all motors analyzed. The base hourly rate was 

developed from the 2002 Economic Census of Industry2

 by the U.S. Census Bureau. Several 

markups were applied to this hourly rate to obtain a fully burdened rate which was intended to be 

representative of the labor costs associated with manufacturing these motors. Table 5.4.1 shows 

the markups that were applied and their corresponding markup percentage and new burdened 

labor rate. 

Table 5.4.1 Labor Markups for Small Electric Motor Manufacturers

Item description Markup percentage Rate per hour 

Labor cost per hour٭ $ 13.55 

Indirect Production٭٭ 33 % $ 18.02 

 23.43 $ % 30 ٭٭٭Overhead

Fringe† 28 % $ 29.99 

Assembly Labor Up-time†† 43 % $ 42.88 

Non-Production Mark-up††† 37% $ 58.75 

Cost of Labor Input to Spreadsheet $ 58.75 

٭ Cost per hour is from U.S. Census Bureau, 2002 Economic Census of Industry, published December 2004, Table 

5, page 5. Data for NAICS code 3353121 “Fractional Horsepower Motors” Production workers hours and wages. 

٭٭ Indirect Production Labor (Production managers, quality control, etc.) 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, 2002 Economic Census of Industry, published December 2004, Table 3, page 3. Data for NAICS code 

335312 “Motors and generator manufacturing,” 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 product 

and/or reworking unsatisfactory units. The markup of 43 percent represents a 70 percent utilization (multiplying by 

100/70). NCI estimate. 

††† Non-production markup reflects non-production costs, including sale and general administrative, research and 

development, interest payments, and profit factor markups. Source: SEC 10-K reports for A.O. Smith, Baldor, 

Emerson, and Regal-Beloit. 

 As discussed above, the small electric motor design software provides an estimated 

manufacturing time for each design. The software apportions the labor time estimates into two 

categories: fixed and variable components. Similar to the material costs, there are subheadings 

within these categories that identify the activity or process being carried out, such as stator 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-11 

assembly. Summing the list of process steps gives a final time estimate for manufacturing the 

motor, which is multiplied by the fully burdened labor cost. Since markups are already applied to 

the labor rate, no additional markups were applied to the calculated fully burdened labor cost. 

 In consultation with manufacturers, DOE learned that the amount of time necessary to 

build a motor with a longer stack or more copper wirings is considered negligible. Therefore, 

there was only one process step that DOE calculated as a variable labor cost, namely the “Rotor 

Core Assembly” process. This activity changed to a longer time when the subcontractor’s 

designs called for both a copper rotor and the premium steel, Hiperco 50TM. This change occurs 

when going from premium plus models to the maximum technology (max tech) models for each 

set of small electric motor designs. 

 The remainder and the majority of the labor costs calculated were fixed costs. The 

following subheadings are associated with the fixed cost labor estimates: stator assembly, rotor 

assembly, end cap assembly, housing assembly, hardware, and final assembly. The stator 

assembly list includes time estimates for punching and stacking the laminations, adding slot 

liner, winding coils, inserting coils, forming end-turns, lead stripping and terminal placement, 

magnet wire or lead splicing, using the stator test system, and applying the varnish. Adding the 

fan, machining the shaft, pressing the shaft onto the rotor, balancing the rotor, and heat shrinking 

bearings onto the shaft are labor steps under the rotor assembly subheading. For end cap 

assembly there are times for machining the bearing bore at each end, pressing the cap, washing, 

and performing the die-cast press. The labor times under the hardware section are estimates of 

adding the components to the motor. Various washers, bolts, studs, screws, grommets for 

capacitor wire (when applicable), start and/or run capacitors (when applicable), and a start switch 

(when applicable) are among these hardware components. The last section for fixed labor costs is 

the final assembly section that includes times for actual assembly, motor testing, labeling and 

packaging. 

5.4.3 Manufacturer Markups 

 DOE used the three markups described below to account for non-production costs that 

are part of each motor leaving a manufacturer’s facility. Scrap factors, overhead costs, and nonproduction markups will vary from manufacturer to manufacturer because their profit margins, 

overheads, prices paid for goods, and business structures vary. DOE prepared estimates for these 

three non-production cost manufacturer markups from SEC-10K reports and conversations with 

manufacturers and experts. 

• Handling and scrap factor: 2.5 percent markup. This markup was applied to the direct 

material production costs of each motor. 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 small electric motor (e.g., lengths of wire too short to wind). 

• Factory overhead: 12.5 percent markup. Factory overhead includes all the indirect costs 

associated with production, indirect materials and energy use, taxes, and insurance. DOE 

only applies factory overhead to the direct material production costs (including the 

handling and scrap factor). 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-12 

• Non-production: 37 percent markup. This markup reflects costs including sales and 

general administrative, research and development, interest payments, and profit factor. 

DOE applies the non-production markup to the sum of the direct material production, the 

direct labor, and the factory overhead. Note that this markup is also shown in Table 5.4.1 

and is accounted for in the fully burdened labor rate applied to the labor time estimates. 

5.5 RESULTS OF ENGINEERING ANALYSIS 

 For each of the four motors presented above, DOE developed five designs using a motor 

design software tool. These included a baseline design and four more efficient designs above the 

efficiency of the baseline motor. Then by using a consistent methodology and pricing scheme 

including material and labor costs and manufacturer’s markups, DOE developed manufacturer 

selling prices for the baseline and more efficient motor designs. Throughout this section, DOE 

will refer to these bottoms-up derived and manufacturer marked-up selling prices as 

“manufacturer selling prices.” 

 Thus, the engineering analysis results are essentially four manufacturer selling priceversus-efficiency curves that represent the four motors analyzed from the representative 

equipment classes. The eight graphs shown in Figure 5.5.1 through Figure 5.5.8 provide the 

manufacturer selling price versus efficiency curves and Table 5.5.1 through Table 5.5.8 present 

the tabulated results. 

5.5.1 Polyphase, 1 Horsepower, 4-Pole, 56-Frame Motor 

Figure 5.5.1 presents the relationship between the manufacturer selling price and full-load 

efficiency for the polyphase motor analyzed. DOE developed a maximum technology (maxtech) design using a non-traditional steel type (i.e., Hiperco 50TM) that makes the motor 

considerably more expensive than other designs analyzed. Use of this premium electromagnetic 

steel greatly increases the cost to manufacture a motor and consequently the manufacturer selling 

price, extending the Y-axis. For this reason, the engineering analysis results are presented twice, 

first with the max tech design (Figure 5.5.1) and then again without the max tech design (Figure 

5.5.2). 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-13 

$0

$200

$400

$600

$800

$1,000

$1,200

$1,400

$1,600

$1,800

$2,000

74.0 76.0 78.0 80.0 82.0 84.0 86.0 88.0 90.0 92.0

Full Load Efficiency (%)

Manufacturer Selling Price ($)

Figure 5.5.1. Polyphase 1 Horsepower, 4-Pole, 56-Frame Motor Engineering 

Analysis, with Maximum Technology Point 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-14 

$0

$50

$100

$150

$200

$250

74.0 76.0 78.0 80.0 82.0 84.0 86.0 88.0 90.0 92.0

Full Load Efficiency (%)

Manufacturer Selling Price ($)

Figure 5.5.2. Polyphase 1 Horsepower, 4-Pole, 56-Frame Motor Engineering Analysis, 

without Maximum Technology Point 

 Table 5.5.1 presents the same engineering analysis results in a tabular form, including the 

full-load efficiency values and the MSPs. Moving from the baseline motor to the premium plus 

motor, DOE found that the full-load efficiency would increase 10.9 percentage points, for about 

a 14-percent improvement over the baseline motor. Raising the efficiency to that level caused 

the MSP to more than double, increasing from $93.46 for the baseline model to $221.35 for the 

premium plus motor. 

Table 5.5.1. Efficiency and MSP Data for Polyphase Motor 

Motor Design Efficiency (%) Manufacturer Selling Price ($) 

Baseline 75.8 % $ 93.46 

Energy Efficient 81.5 % $ 105.23 

Premium 85.5 % $ 131.55 

Premium Plus 86.7 % $ 221.35 

Max Tech 90.4 % $ 1,785.49 

 Table 5.5.2 presents some of the design and performance specifications associated with 

the five polyphase designs presented above. To convey additional information on a few of these 

designs, DOE prepared appendix 5A to the preliminary TSD, which presents detailed design and 

performance specification on one motor design (i.e., the premium motor design) from each of the 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-15 

representative motors analyzed. For the polyphase motor designs prepared, DOE presents 

detailed design information on the premium motor design, which is 85.5 percent efficient and has 

a manufacturer’s selling price of $131.55. 

Table 5.5.2. Polyphase, 1 Horsepower, 4-Pole, 56-Frame Motor Designs 

Parameter Units Baseline Energy 

Efficient Premium Premium Plus Max Tech 

Efficiency % 75.8 81.5 85.5 86.7 90.4 

Line Voltage V 230 230 230 230 230 

Speed RPM 1714 1703 1709 1719 1729 

Torque oz-ft 49.6 51.2 49.8 51.4 48.3 

Current A 4.5 4.0 4.0 3.9 3.1 

Steel 24M56 24M56 24M19 29M15 Hiperco 50 

0.006 

Rotor Conductor 

Material Aluminum Aluminum Aluminum Copper Copper 

Main Wire AWG 19.0 20.0 19.0 20.5 19.0 

Main Wire Weight lbs 2.530 4.250 5.480 5.850 9.584 

Rotor Conductor 

Weight lbs 1.069 1.078 1.174 1.900 4.890 

Peak Slot Fill % 32.0 55.0 68.4 74.6 73.9 

Locked Rotor Torque oz-ft 125.0 128.0 125.0 127.0 124.0 

Locked Rotor Current A 18.5 17.5 17.5 18.6 18.2 

Stack Length in 2.75 2.85 3.00 3.00 3.50 

Laminations per Stack # 110 114 120 215 584 

Housing Weight lbs 6.41 6.50 6.60 6.60 7.56 

Slot Liner in2

126.186 130.818 137.522 137.522 160.440 

Slot Peg in216.319 16.917 17.795 17.795 20.640 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-16 

5.5.2 Capacitor-Start, Induction-Run, 1/2 Horsepower, 4-Pole, 56-Frame Motor 

Figure 5.5.3 presents the relationship between the MSP and full-load efficiency for the 

56-frame capacitor-start, induction-run motor. The max-tech design incorporates a high-grade 

premium electromagnetic steel alloy that is much more expensive than the high quality 

electromagnetic steel alloy used in the premium plus (second most efficient) design. Use of such 

steel greatly increases the MSP of the motor, thereby distorting the Y-axis. For this reason, the 

engineering analysis results are presented again without the max tech design in Figure 5.5.4. 

$0

$200

$400

$600

$800

$1,000

$1,200

$1,400

$1,600

$1,800

62.0 64.0 66.0 68.0 70.0 72.0 74.0 76.0 78.0 80.0

Full Load Efficiency (%)

Manufacturer Selling Price ($)

Figure 5.5.3. Capacitor-Start, Induction-Run, 1⁄2 Horsepower, 4-Pole, 56-Frame 

Engineering Analysis Curve, with Maximum Technology Point 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-17 

$0

$50

$100

$150

$200

$250

62.0 64.0 66.0 68.0 70.0 72.0 74.0 76.0 78.0 80.0

Full Load Efficiency (%)

Manufacturer Selling Price ($)

Figure 5.5.4. Capacitor-Start, Induction-Run, 1⁄2 Horsepower, 4-Pole, 56-Frame 

Engineering Analysis Curve, without Maximum Technology Point 

 Table 5.5.3 presents the same engineering analysis results in a tabular form, including the 

full-load efficiency values and the MSPs. Moving from the baseline motor to the premium plus 

motor, DOE found that the full-load efficiency would increase 16 percentage points, for about a 

25-percent improvement over the baseline motor. Raising the efficiency to that level caused the 

MSP to more than double, increasing from $105.61 for the baseline model to $213.82 for the 

premium plus motor. 

Table 5.5.3. Efficiency and MSP Data for Capacitor-Start, Induction-Run, 56-Frame 

Motor 

Motor Design Efficiency (%) Manufacturer Selling Price ($) 

Baseline 63.3 % $ 105.61 

Energy Efficient 68.7 % $ 112.86 

Premium 75.2 % $ 136.51 

Premium Plus 79.3 % $ 213.82 

Max Tech 79.3 % $ 1,532.94 

 Table 5.5.4 presents some of the design and performance specifications associated with 

the five CSIR 56-frame designs presented above. DOE also provides additional design detail and 

performance specifications for the premium motor design in the preliminary TSD, appendix 5A. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-18 

Table 5.5.4. Capacitor-Start, Induction-Run, 1/2 Horsepower, 4-Pole, 56-Frame Motor 

Designs 

Parameter Units Baseline Energy 

Efficient Premium Premium Plus Max Tech 

Efficiency % 63.3 68.7 75.2 79.3 79.3 

Line Voltage V 115 115 115 115 115 

Speed RPM 1727 1727 1727 1760 1760 

Torque oz-ft 24.37 24.44 26.41 24.13 24.13 

Current A 9.17 7.98 8.48 8.18 8.18 

Steel 24M56 24M56 24M19 29M15 Hiperco 

50 0.006 

Rotor Conductor 

Material 

Aluminum Aluminum Aluminum Copper Copper 

Main Wire AWG 20.5 20 19 19 20 

Auxiliary Wire AWG 20.5 20 19.5 19 19 

Main Wire Weight lbs 2.586 3.063 3.777 3.777 5.117 

Auxiliary Wire Weight lbs 0.955 1.101 1.327 1 1.068 

Rotor Conductor 

Weight lbs 0.723 1.06 1.09 1.71 2.67 

Start Capacitor μF 300 300 300 450 450 

Peak Slot Fill % 58.82 65.97 74.95 74.12 74.7 

Locked Rotor Torque oz-ft 85 85.2 87.08 90.22 93.78 

Locked Rotor Current A 36.1 34.6 37.5 41.16 38 

Stack Length in 2 2.3 2.6 2.6 3 

Laminations per Stack # 80 92 104 186 500 

Housing Weight lbs 6.1 6.15 6.3 6.3 7.245 

Slot Liner in2 91.71 105.56 119.17 119.17 137.3 

Slot Peg in2 11.86 13.66 15.42 15.42 17.71 

5.5.3 Capacitor-Start, Induction-Run, 1/2 Horsepower, 4-Pole, 48-Frame Motor 

 Figure 5.5.5 presents the relationship between the MSP and full-load efficiency for the 

48-frame capacitor-start, induction-run motor. The max-tech design incorporates a high-grade 

premium electromagnetic steel alloy that is much more expensive than the high quality 

electromagnetic steel alloy used in the premium plus (second most efficient) design. Use of such 

steel greatly increases the MSP of the motor, thereby the Y-axis. For this reason, the engineering 

analysis results are presented again without the max tech design in Figure 5.5.6. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-19 

$0

$200

$400

$600

$800

$1,000

$1,200

$1,400

$1,600

$1,800

60.0 62.0 64.0 66.0 68.0 70.0 72.0 74.0 76.0 78.0 80.0 82.0 84.0

Full Load Efficiency (%)

Manufacturer Selling Price ($)

Figure 5.5.5. Capacitor-Start, Induction-Run, 1⁄2 Horsepower, 4-Pole, 48-Frame 

Engineering Analysis Curve, with Maximum Technology Point 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-20 

$0

$50

$100

$150

$200

$250

60.0 62.0 64.0 66.0 68.0 70.0 72.0 74.0 76.0 78.0 80.0 82.0 84.0

Full Load Efficiency (%)

Manufacturer Selling Price ($)

Figure 5.5.6. Capacitor-Start, Induction-Run, 1⁄2 Horsepower, 4-Pole, 48-Frame 

Engineering Analysis Curve, without Maximum Technology Point 

 Table 5.5.5 presents the same engineering analysis results in a tabular form, including the 

full-load efficiency values and the MSPs. Moving from the baseline motor to the premium plus 

motor, DOE found that the full-load efficiency would increase 19.4 percentage points, for about 

a 31-percent improvement over the baseline motor. Raising the efficiency to that level caused the 

MSP to more than double, increasing from $96.97 for the baseline model to $212.40 for the 

premium plus motor. 

Table 5.5.5. Efficiency and MSP Data for Capacitor-Start, Induction-Run, 48-Frame 

Motor 

Motor Design Efficiency (%) Manufacturer Selling Price ($) 

Baseline 62.3 % $ 96.97 

Energy Efficient 69.5 % $ 105.79 

Premium 74.1 % $ 120.00 

Premium Plus 81.7 % $ 212.40 

Max Tech 82.0 % $ 1,547.11 

 Table 5.5.6 presents some of the design and performance specifications associated with 

the five CSIR 48-frame designs presented above. DOE also provides additional design detail 

and performance specifications for the premium motor design in appendix 5A of the preliminary 

TSD. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-21 

Table 5.5.6. Capacitor-Start, Induction-Run, 1/2 Horsepower, 4-Pole, 48-Frame Motor 

Designs 

Parameter Units Baseline Energy 

Efficient Premium Premium Plus Max Tech 

Efficiency % 62.3 69.5 74.1 81.7 82.0 

Line Voltage V 115 115 115 115 115 

Speed RPM 1737 1736 1738 1765 1743 

Torque oz-ft 24.2 24.4 24.2 24.2 24.2 

Current A 9.0 8.1 8.1 7.3 6.7 

Steel 24M56 24M56 24M19 29M15 Hiperco 50 

0.006 

Rotor Conductor 

Material Aluminum Aluminum Aluminum Copper Copper 

Main Wire AWG 19.5 20.5 20.5 20.0 20.5 

Auxiliary Wire AWG 20.0 20.0 20.0 21.5 21.5 

Main Wire Weight lbs 1.561 2.591 2.636 3.114 4.498 

Auxiliary Wire Weight lbs 0.916 0.957 0.974 1.155 1.262 

Rotor Conductor 

Weight lbs 0.645 0.675 0.688 2.392 3.990 

Start Capacitor μF 300 300 300 440 440 

Peak Slot Fill % 49.0 72.2 72.2 74.9 74.6 

Locked Rotor Torque oz-ft 85.3 89.2 90.1 84.1 114.3 

Locked Rotor Current A 35.1 34.3 34.4 45.2 42.2 

Stack Length in 2.65 2.90 3.00 3.40 4.00 

Laminations per Stack # 106 116 120 243 667 

Housing Weight lbs 4.70 4.90 5.00 5.50 6.65 

Slot Liner in2121.440 133.008 137.575 155.920 188.990 

Slot Peg in2

15.710 17.211 17.802 20.177 24.410 

5.5.4 Capacitor-Start, Capacitor-Run, 3/4 Horsepower, 4-Pole, 56-Frame Motor 

Figure 5.5.7 presents the relationship between the MSP and full-load efficiency for the 

CSCR motor. The max-tech design incorporates a high-grade premium electromagnetic steel 

alloy that is much more expensive than the high quality electromagnetic steel alloy used in the 

premium plus (second most efficient) design. Use of such steel greatly increases the MSP of the 

motor, thereby distorting the Y-axis. For this reason, the engineering analysis results are 

presented again without the max tech design in Figure 5.5.8. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-22 

$0

$200

$400

$600

$800

$1,000

$1,200

$1,400

$1,600

$1,800

$2,000

$2,200

66.0 68.0 70.0 72.0 74.0 76.0 78.0 80.0 82.0 84.0 86.0 88.0 90.0

Full Load Efficiency (%)

Manufacturer Selling Price ($)

Figure 5.5.7. Capacitor-Start, Capacitor-Run 3⁄4 Horsepower, 4-Pole, 56-Frame 

Engineering Analysis Curve, with Maximum Technology Point 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-23 

$0

$50

$100

$150

$200

$250

$300

66.0 68.0 70.0 72.0 74.0 76.0 78.0 80.0 82.0 84.0 86.0 88.0 90.0

Full Load Efficiency (%)

Manufacturer Selling Price ($)

Figure 5.5.8. Capacitor-Start, Capacitor-Run 3⁄4 Horsepower, 4-Pole, 56-Frame 

Engineering Analysis Curve, without Maximum Technology Point 

 Table 5.5.7 presents the same engineering analysis results in tabular form, including the 

full-load efficiency values and the MSPs. Moving from the baseline motor to the premium plus 

motor, DOE found that the full-load efficiency would increase 18.4 percentage points, for about 

a 27-percent improvement over the baseline motor. Raising the efficiency to that level caused the 

MSP to more than double, increasing from $116.17 for the baseline model to $259.78 for the 

premium plus motor. 

Table 5.5.7. Efficiency and MSP Data for Capacitor-Start, Capacitor-Run Motor 

Motor Design Efficiency (%) Manufacturer Selling Price ($) 

Baseline 68.6 % $ 116.17 

Energy Efficient 77.1 % $ 124.33 

Premium 82.9 % $ 149.50 

Premium Plus 87.0 % $ 259.78 

Max Tech 88.3 % $ 2,024.82 

 Table 5.5.8 presents some of the design and performance specifications associated with 

the five CSCR designs presented above. DOE also provides additional design detail and 

performance specifications for the premium motor design in the preliminary TSD, appendix 5A. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-24 

Table 5.5.8. Capacitor-Start, Capacitor-Run, 3/4 Horsepower, 4-Pole, 56-Frame Motor 

Parameter Units Baseline Energy 

Efficient Premium Premium Plus Max Tech 

Efficiency % 68.6 77.1 82.9 87.0 88.3 

Line Voltage V 115 115 115 115 115 

Speed RPM 1725 1732 1735 1759 1745 

Torque oz-ft 36.4 37.6 36.6 36.4 35.9 

Current A 11.6 8.7 7.6 7.3 6.3 

Steel 24M56 24M56 24M19 29M15 Hiperco 50 

0.006 

Rotor Conductor 

Material 

Aluminu

m 

Aluminum Aluminu

m 

Copper Copper 

Main Wire AWG 20.5 19.5 19.0 20.0 19.0 

Auxiliary Wire AWG 20.0 20.0 21.5 20.0 20.0 

Main Wire Weight lbs 2.201 2.937 3.354 4.124 5.745 

Auxiliary Wire Weight lbs 0.741 0.699 1.104 1.495 1.614 

Rotor Conductor 

Weight lbs 0.778 1.123 1.136 2.242 3.516 

Start Capacitor μF 550 550 400 550 550 

Run Capacitor μF 20 45 50 50 50 

Peak Slot Fill % 44.7 55.7 61.6 74.2 71.7 

Locked Rotor Torque oz-ft 119.4 119.2 126.7 129.9 156.4 

Locked Rotor Current A 51.2 46.9 39.7 53.3 52.1 

Stack Length in 2.60 2.95 3.10 3.30 4.00 

Laminations per Stack # 104 118 124 236 667 

Housing Weight lbs 6.10 6.15 6.30 6.50 7.86 

Slot Liner in2119.168 135.261 142.164 151.220 183.030 

Slot Peg in2

14.904 17.503 18.396 19.567 23.660 

5.6 SCALING RELATIONSHIPS 

 In order to reduce the analytical burden associated with conducting a detailed engineering 

analysis of the cost-efficiency relationship on all 72 equipment classes, DOE developed an 

analytical approach that reduced the number of small electric motors it analyzed while retaining 

reasonable levels of accuracy. DOE selected one baseline model from each motor category to 

evaluate in the engineering and the life-cycle cost analysis (see preliminary TSD chapter 8). It 

then extrapolated the results of this analysis from the unit studied to the other equipment classes. 

This section describes the methodology DOE followed to develop equations and constants that 

would enable scaling of analytical results to equipment classes that were not analyzed. 

5.6.1 Interpolation of Cost-Efficiency Points 

 The subcontractor’s small electric motor designs are a series of points that describe the 

relationship between MSP and efficiency. These results are presented in Figure 5.5.1 through 

Figure 5.5.8 in this chapter. This analysis provides a series of discrete points for each of the 

motors, but does not necessarily describe the shape of the MSP-efficiency curve in between these 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-25 

points. Due to the fact that the efficiency levels across the various equipment classes may not 

coincide with the precise efficiency values of the subcontractor’s motor designs, DOE needed to 

develop an approach for interpolating the MSP-efficiency curve between the actual designs. 

 DOE considered two interpolation approaches, linear interpolation and power law 

interpolation. Linear interpolation is simply a straight line connecting the discrete cost-efficiency 

points for each motor design. This approach holds the MSP-efficiency slope constant between 

each pair of points, and therefore may overestimate MSP for a given interpolated efficiency 

level. The power law interpolation technique generates a MSP-efficiency curve between each set 

of points that more closely resembles that of the overall curve. That is, the power law curve 

results in a better fit of the data and therefore a more accurate representation of the MSP at any 

interpolated efficiency value. The following equations describe power law interpolation between 

two points (X1, Y1) and (X2, Y2) to point (X, Y): 

•

P XXYY )/(

1 ×= 1

• where ))ln()/(ln())ln()(ln( 2 −= 1 2 − XXYYP 1

The following figure presents the difference between the linear and power law 

interpolation for a section of the small polyphase electric motor analysis. DOE selected the 

power law interpolation technique for all the representative models analyzed. 

$90

$110

$130

$150

$170

$190

$210

$230

80% 81% 82% 83% 84% 85% 86% 87% 88%

Linear Interpolation

Power Law Interpolation

Figure 5.6.1 Polyphase Motor Designs with Interpolated Curve Fits 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-26 

5.6.2 Motor Losses 

After DOE determined the method it would use to interpolate between individual small 

electric motor designs, DOE developed an approach to scale motor losses between equipment 

classes. The first step DOE took to develop scaling relationships was creating a model that 

describes motor losses as a function of the motor’s rated horsepower. To do this, DOE examined 

the standards adopted by the Energy Independence and Security Act of 2007 (EISA). For 

polyphase, general-purpose motors, built in a three digit frame size, EISA adopted the NEMA 

Premium Standards, shown in NEMA MG 1-2006 in Table 12-12, as the minimum efficiency 

levels. This table has standards for motors ranging in horsepower from 1 to 200 horsepower, in 

two-, four-, and six-pole configurations, and in open and enclosed constructions. DOE plotted 

this data in two ways to observe any trends: 

• Delta (defined as 100 – efficiency level) versus horsepower and 

• Delta as a percentage of rating (or (100 – efficiency level)/efficiency level) versus 

horsepower 

If plotted on logarithmic scales, DOE observed that as horsepower increased, delta 

decreased following a power law function, as shown in Figure 5.6.2. The power law for this 

particular function is that delta scales according to a negative 0.25 exponent as horsepower 

increases. That is: 

•

25.0

)(

−

×= hpChpDelta , where C is a constant for a particular pole configuration and 

motor category combination 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-27 

y = 23.364x-0.2809

R2 = 0.9708

y = 17.052x-0.2727

R2 = 0.9868

y = 18.013x-0.2658

R2 = 0.9817

1

10

100

1 10 100 1000

Rated Electric Motor Horsepower

(1/efficiency - 1)

EISA Open Motor 6 pole

EISA Open Motor 4 pole

EISA Open Motor 2 pole

Power (EISA Open Motor 2 pole)

Power (EISA Open Motor 4 pole)

Power (EISA Open Motor 6 pole)

Figure 5.6.2 Function of Delta with Horsepower for 1-200 Horsepower,Energy 

Independence and Security Act of 2007 Efficiency Standards 

5.6.3 Candidate Standard Levels 

 DOE uses candidate standard levels (CSLs) as incremental units of analysis in the lifecycle cost assessment (see preliminary TSD chapter 8) and the national impacts analysis (see 

preliminary TSD chapter 10). In order to develop appropriate CSLs for small electric motors, 

DOE used the trends observed in its analysis of the EISA standard levels. The EISA standards 

that reference Table 12-12 of NEMA MG 1-2006 are for polyphase motors. Therefore, DOE 

used the EISA 2007 efficiency standard for 1 hp, four-pole, open construction motors as a basis 

for selecting CSLs for the 1 hp, four-pole polyphase motor examined for this engineering 

analysis. The EISA 2007 standard, which is the NEMA Premium level, is 85.5 percent for 1 hp, 

four-pole, open construction motors. DOE wanted to have at least one analysis evaluation point 

below this level, therefore it selected an efficiency rating of 84.0 percent for CSL1. From there, 

four more CSLs were chosen at increasing efficiency ratings, up to a level near the maximum 

technology efficiency level of the polyphase motor analyzed. The efficiency values were spaced 

across the efficiency continuum for the polyphase motor analyzed in order to ensure DOE 

conducted economic analysis across a well distributed range of efficiency values. The efficiency 

values selected are shown in Table 5.6.1 below, along with the CSL’s for the CSIR and CSCR 

equipment classes that were analyzed. CSL2 was selected as the efficiency rating approximately 

equivalent to the EISA 2007 level for 1-200 horsepower motors (i.e., the NEMA Premium level). 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-28 

Table 5.6.1 Candidate Standard Levels for Equipment Classes Analyzed 

Candidate Standard 

Level 

Polyphase, 56 Frame

4-pole, 1 hp 

CSIR, 48 Frame, 

4-pole, 0.5 hp 

CSCR, 56 Frame, 

4-pole, 0.75 hp 

CSL 1 84.0% 70.8% 80.2% 

CSL 2 85.5% 73.6% 82.0% 

CSL 3 86.5% 75.4% 83.3% 

CSL 4 88.0% 78.1% 85.1% 

CSL 5 90.0% 81.8% 87.6% 

 Besides scaling the candidate standard levels for the 1 hp, four-pole polyphase small 

electric motor to appropriate levels for CSIR and CSCR motors, DOE also needed to scale to 

other horsepower levels and pole configurations for polyphase small electric motors. These 

relationships are derived using the above power law equation and the following equation: 

Efficiency hp = − hpDelta )(%100)(

 Consider the following sets of equations which describe four-pole, polyphase motors, 

where hp is 1 horsepower level (in our case it is 1) and hp’ is the level being scaled to: 

1. Efficiency hp = − hpDelta ⇔ hpDelta = %100)()(%100)( − Efficiency hp)(

2. 25.0

)(

−

×= hpChpDelta

3. Efficiency hp = − hpDelta ⇔ hpDelta = %100)'()'(%100)'( − Efficiency hp )'(

4. 25.0')'(

−

×= hpChpDelta

 Since these equations describe the same set of motors (four-pole, polyphase), C is the 

same for equations 2 and 4. Solving for C and setting equal gives the following: 

5. 25.0 25.0

'

)'()(

− −

=

hp

hpDelta

hp

hpDelta

 Equation 5 can be manipulated to obtain the following description of delta: 

6. 25.0

25.0

25..0

)

'

)((

'

)()'(

−

−

−

= =

hp

hp hpDelta

hp

hp hpDeltahpDelta

EERE-2007-BT-STD-0007 COMMENT 07.2
5-29 

 At this point, a substitution can be made into equation 3 to give: 

7. 25.0

)

'

)((%100)'(

−

−=

hp

hp Efficiency hp hpDelta

 As previously discussed, DOE chose CSL’s for a 1 hp polyphase small electric motor. 

Therefore, it is possible to scale these CSL’s to corresponding CSL’s for other horsepowers of 

four-pole polyphase small electric motors by substituting equation 1 in for Delta(hp) and 

plugging in 1 for hp. These substitutions give: 

8. 25.0 %100(%100)'( )'())1(

− Efficiency hp −−= Efficiency × hp , where Efficiency(1) is the 

efficiency rating for a CSL level at 1 horsepower and Efficiency(hp’) is the corresponding 

CSL level at a different horsepower level. 

 Equations similar to 1 through 4 can be manipulated to obtain equations that relate 

scaling from four-pole, polyphase small electric motors to other equipment classes. To do this 

though, DOE assumes that the negative 0.25 scaling rule derived for polyphase small electric 

motors also applies to small CSIR and CSCR motors. Note that DOE found that this rule does 

apply to different pole configurations. 

 The only change that would be made to the original set of equations (1-4) would be a 

change to equation 4. The change would result in the following equation: 

4*. 25.0 25.0

'')'( '

− −

××=×= hpCKhpChpDelta

 In this equation C’ is a variable that represents a factor of change relative to 4-pole 

polyphase motors. The equation is rewritten where K is a multiplier used to describe the relative 

changes in terms of C. Rewriting the equation in terms of C allows DOE to follow the previously 

described steps and obtain an equation similar to 8, but with the variable K: 

9. 25.0 %100(%100)'( )'())1(

− Efficiency hp K −×−= Efficiency × hp

 K changes depending on the change in equipment class. For example, K can describe a 

change in the number of poles, a change in motor category, or a change in both. Therefore, K 

will have different values. 

 To obtain values of K for the motors analyzed, DOE used the cost-efficiency data 

developed in the engineering analysis and equation 9 above. DOE chose a CSL close to the max 

tech efficiency found for the CSIR and CSCR motors. This value was plugged into equation 9 

along with CSL5 for four-pole polyphase small electric motors and the corresponding 

horsepower for the small CSIR or CSCR motors. From there, the equation could be solved for K. 

For CSIR, four-pole motors, K was found to be 1.53 and for CSCR, four-pole motors K was 

found to be 1.15. With the value of K found, the other CSL’s (1 through 4) for four-pole 

polyphase motors, which DOE selected, were plugged into equation 9 to obtain corresponding 

CSL’s for the other two motor categories. These values are shown above in Table 5.6.1. 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-30 

 The K values for polyphase small electric motors, two- and six-pole motors were 

obtained by examining the trend line differences between two-, four-, and six-pole motors. A 

ratio of the coefficient in the power equations describing the three sets of data gave the K value 

for changing from four- to two-pole or four- to six-poles. The K value for changing to a two-pole 

polyphase motor was found as 1.37 and for changing to a six-pole polyphase motor it was found 

to be 1.06. When changing poles and motor category, the resulting K value is a product of the K 

values found for changing the motor category and the number of poles. 

 There are a total of 9 values for the constant K to be calculated, which are presented in 

Table 5.6.2. This provides the K values derived dependant on the motor category and number of 

poles. 

Table 5.6.2 Matrix of K Values used for Scaling Candidate Standard Levels 

Polyphase CSIR CSCR 

6 Poles 1.06 1.62 1.21 

4 Poles 1.00 1.53 1.15 

2 Poles 1.37 2.10 1.58 

 DOE presents values for CSL1 at all equipment classes in Table 5.6.3 through Table 

5.6.5. This serves as an example of how equation 9 and the derived K values are used to 

extrapolate CSL1 (shown in Table 5.6.1) to all 72 equipment classes. 

Table 5.6.3 Candidate Standard Level 1 for Polyphase Small Electric Motors 

Horsepower 6 Poles 4 Poles 2 Poles 

1⁄4 hp (0.18 kW) 76.0% 77.3% 68.9% 

1

/3 hp (0.25 kW) 77.7% 78.9% 71.1% 

1⁄2 hp (0.37 kW) 79.9% 80.9% 73.9% 

3⁄4 hp (0.55 kW) 81.8% 82.8% 76.4% 

1 hp (0.75 kW) 83.0% 84.0% 78.0% 

11⁄2 hp (1.1 kW) 84.7% 85.5% 80.1% 

2 hp (1.5 kW) 85.7% 86.5% 81.5% 

> 3 hp (2.2 kW) 87.1% 87.8% 83.3% 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-31 

Table 5.6.4 Candidate Standard Level 1 for Capacitor-Start, Induction-Run Small 

Electric Motors 

Horsepower 6 Poles 4 Poles 2 Poles 

1⁄4 hp (0.18 kW) 63.4% 65.3% 52.5% 

1

/3 hp (0.25 kW) 65.9% 67.7% 55.8% 

1⁄2 hp (0.37 kW) 69.2% 70.8% 60.1% 

3⁄4 hp (0.55 kW) 72.2% 73.6% 63.9% 

1 hp (0.75 kW) 74.1% 75.5% 66.4% 

11⁄2 hp (1.1 kW) 76.6% 77.8% 69.6% 

2 hp (1.5 kW) 78.2% 79.4% 71.7% 

> 3 hp (2.2 kW) 80.3% 81.3% 74.5% 

Table 5.6.5 Candidate Standard Level 1 for Capacitor-Start, Capacitor-Run Small 

Electric Motors 

Horsepower 6 Poles 4 Poles 2 Poles 

1⁄4 hp (0.18 kW) 72.5% 73.9% 64.3% 

1

/3 hp (0.25 kW) 74.4% 75.7% 66.8% 

1⁄2 hp (0.37 kW) 76.8% 78.1% 70.0% 

3⁄4 hp (0.55 kW) 79.1% 80.2% 72.9% 

1 hp (0.75 kW) 80.5% 81.6% 74.7% 

11⁄2 hp (1.1 kW) 82.4% 83.3% 77.2% 

2 hp (1.5 kW) 83.6% 84.5% 78.8% 

> 3 hp (2.2 kW) 85.2% 86.0% 80.8% 

EERE-2007-BT-STD-0007 COMMENT 07.2
5-32 

REFERENCES 

 

1

 Design Considerations to Optimize Stator Manufacturing, Alliance Winding Equipment, Inc., 

Ft. Wayne, Indiana. Blade-Gap Chart. 

2

 U.S. Census Bureau, 2002 Economic Census of Industry Series Reports for Industry, US 

Department of Commerce, 2003. 

EERE-2007-BT-STD-0007 COMMENT 07.2