i CHAPTER 7. ENERGY USE CHARACTERIZATION

TABLE OF CONTENTS

7.1 INTRODUCTION

................................ ................................ ................................ ............... 1

7.2 ENERGY USE ANALYSIS FOR ELECTRIC MOTORS

................................ ................. 1

7.2.1 Introduction

................................ ................................ ................................ ........ 1

7.2.2 Motor Losses

................................ ................................ ................................ ...... 2

7.2.3 Reactive Power

................................ ................................ ................................ .. 4

7.2.4 Motor Applications

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

7.2.5 Loading

................................ ................................ ................................ .............. 7

7.2.6 Motor Hours of Operation/Duty Factor

................................ ............................. 7

7.3 ANNUAL ENERGY USE

................................ ................................ ................................ ... 9

LIST OF TABLES

Table 7.1.1 Representative Units for Preliminary Analysis

................................ ........................ 1

Table 7.2.1 Polynomial Equation Coefficients for Losses vs. Loading Relationship

................ 2

Table 7.2.2 Polynomial Equation Coefficients for Power Factor vs. Loading

Relationship

................................ ................................ ................................ ............. 4

Table 7.2.3 Distribution of Motors by Application for NEMA Design A and B Motors

(in percent)

................................ ................................ ................................ ............... 6

Table 7.2.4 Distribution of Motors by Application for NEMA Design C Motors (in

percent)

................................ ................................ ................................ .................... 6

Table 7.2.5 Motor Distribution across Sector by Motor Size

................................ .................... 7

Table 7.2. 6 Average Motor Loading by Application

................................ ................................ .. 7

Table 7.2.7 Average Motor Operating Hours by Application and Horsepower Range

.............. 9

Table 7.3.1 Average Annual Energy Consumption by Efficiency Level for

Representative Units

................................ ................................ .............................. 10

LIST OF FIGURES

Figure 7.2.1 Cumulative Distribution for 21

- 50 Horsepower Motors by Applications in

Industry Sector.

................................ ................................ ................................ ........ 81 CHAPTER 7. ENERGY USE CHARACTER IZATION

7.1 INTRODUCTION

A k ey component of the life

- cycle cost (LCC) and payback period (PBP) calculations

described in chapter 8 of the Technical Support Document is the savings in operating costs that

customers would realize from more energy efficient equipment. Energy costs are t he most

significant component of customer operating costs. The U.S. Department of Energy (DOE) uses

annual energy use, along with energy prices, to establish energy costs at various energy

efficiency levels. This chapter describes how DOE determined the a nnual energy use of electric

motors.

The analysis focuses on eight representative units identified in the engineering analysis

(chapter 5) and for which engineering analysis outputs were obtained. ( Table 7.1

. 1 )

Table 7.1

. 1 Representative Units for Preliminary Analysis

Representative

Unit Equipment class

Group Specifications Horsepower

1 NEMA Design s

A & B NEMA Design B, T

- frame,

e nclosed, 4

- pole 5

2 30

3 75

4 NEMA Design C NEMA Design C, T

- frame,

e nclosed, 4

- pole 5

5 50

6

Fire Pump Uses same engineering

outputs as units 1, 2, and 3 5

7 30

8 75

7.2 ENERGY USE ANALYSIS FOR ELECTRIC MOTORS

7.2.1 Introduction

The energy use by electric motors is derive d from three components: energy converted to

useful mechanical shaft power, motor losses, and reactive power. Motor losses consist of I 2 R

losses (both stator and rotor) , core losses, stray

- load losses

, and friction and windage losses. 1

Core losses and friction and windage losses are relatively constant with variations in motor

loading, while I 2 R losses increase with the square of the motor loading. Stray

- load losses are also

dependent upon loading. DOE models the I 2 R losses and stray

- load losses as load

- dependent

losses.2 7.2.2 Motor Losses

For each representative unit, DOE obtained data on part load motor losses from test data

developed in the engineering analysis (chapter 5). Based on the te st data, DOE modeled the

motor losses as a function of loading using a third degree polynomial equation 2 :

Loss ( L )

= A + B × L + C × L 2 + D × L 3

where:

Loss(L ) = the losses of the motor at loading L in watts

L = motor loading as a fraction of rated power in percent

A/B/C/D

= polynomial equation coefficients

Table 7.2

. 1 presents the polynomial equation coefficients for modeling losses as a

function of loading for the eight representative units at each efficiency level analyzed by DOE.

These efficiency levels correspond to the candidate standard levels (CSLs) analyzed in the

engineering analysis (chapter 5).

Table 7.2

. 1 Polynomial Equation Coefficients for Losses vs. Loading Relationship

Representative

Unit CSL A B C D

1 0 234.2 115.8 273.4 168.0

1 169.6 51.2 208.8 103.4

2 158.0 77.8 68.3 133.6

3 150.3 21.8 182.8 50.4

4 143.5 63.0 110.5 51.8

5 135.3 29.2 147.8 25.2

2 0 1059.3 181.4 1052.5 332.3

1 863.1

- 14.8 856.3 136.1

2 639.7 102.7 586.8 201.1

3 509.6 17.5 622.2 253.9

4 444.6 228.4 358.3 271.3

5 444.6 228.4 358.3 271.3

3 0 1775.2 267.1 1757.2 411.8

1 1599.4 91.3 1581.4 236.0

2 870.8 280.9 1037.9 508.1

3 809.6 219.7 976.7 446.9

4 653.5 1006.4

- 261.5 811.8

5 608.3 961.2

- 306.7 766.6

4 0 220.3 62.5 159.7 90.3

1 202.0 85.7 67.8 82.1

2 194.2 74.6 76.2 60.3

3 179.7 36.1 115.0 38.03 5 0 1177.8 106.3 1240.8 282.6

1 829.6 970.7

- 111.9 650.4

2 781.6 907.0

- 140.1 622.2

3 609.3 1019.3

- 575.5 910.2

0 169.6 51.2 208.8 103.4

1 158.0 77.8 68.3 133.6

6 2 150.3 21.8 182.8 50.4

3 143.5 63.0 110.5 51.8

4 135.3 29.2 147.8 25.2

0 863.1

- 14.8 856.3 136.1

1 639.7 102.7 586.8 201.1

7 2 509.6 17.5 622.2 253.9

3 444.6 228.4 358.3 271.3

4 444.6 228.4 358.3 271.3

0 1599.4 91.3 1581.4 236.0

1 870.8 280.9 1037.9 508.1

8 2 809.6 219.7 976.7 446.9

3 653.5 1006.4

- 261.5 811.8

4 608.3 961.2

- 306.7 766.6

To determine the annual energy losses E loss in kilowatt

- hours (kWh), DOE converts the

full

- load losses into part

- load losses using the estimate of the motor’s loading, and multiplies by

the annual operating hours

. Annual energy losses are represented by the following equation:

E loss = H

op × Loss (L )

w here:

E loss = annual energy consumed by motor losses in watts per hour

H

op = the annual operating hours, also known as the duty factor in hours

L = motor loading as a fraction of rated power in percent

7.2.2

. 1 Impact of Higher Operating Speeds

DOE is aware that the installation of a more efficient motor could lead to less energy

savings than anticipated. According to comments from interested parties , a more efficient motor

typically has less slip than a less efficient motor, which is an attribut e that can result in a higher

operating speed and potential ly overloading the motor.

DOE acknowledges that the cubic relation between speed and power requirement in

many variable torque applications can affect the benefits gained by efficient motors, wh ich have

a lower slip. DOE did not obtain sufficient data to incorporate this effect into the LCC analysis.

Instead, DOE incorporated this effect as a sensitivity analysis in the LCC spreadsheet , allowing

the user to consider this effect following a scenar io which described in Appendix 7

- A of the

technical support document (TSD).4 7.2.3 Reactive Power

In an alternating current power system, the reactive power is the root mean square

(RMS) voltage times the RMS current, multiplied by the sine of the phase differen ce between the

voltage and the current. Reactive power occurs when the inductance or capacitance of the load

shifts the phase of the voltage relative to the phase of the current. While reactive power does not

consume energy directly, it can increase losses and costs for the electricity distribution system.

Motors tend to create reactive power because the windings in the motor coils have high

inductance.

Alternating

- current power flow has three components: real power ( P ), measured in watts

(W); apparent po wer ( S ), measured in volt

- amperes (VA); and reactive power ( Q ), measured in

reactive volt

- amperes (VAr). The power factor is defined as P / S . In the case of a perfectly

sinusoidal waveform, P

, Q

, and S can be expressed as vectors that form a vector triangle such

that: S 2 = P 2 + Q 2 . This implies that the formula for reactive power as a function of real power

and power factor is as follows:

Q = P * (1/PF 2

- 1)

w here:

Q = reactive power in reactive volt

- amperes

, P = real power in watts , and

PF = the motor’s power factor

.

DOE used data on motor power factor as a function of motor loading from test data

developed in the e ngineering a nalysis (TSD chapter 5) to develop a relationship between power

factor and motor loading. This relationship is expressed as a third degree polynomial:

PF ( L )

= A + B × L + C × L 2 + D × L 3

Table 7.2

. 2 present s the polynomial equation coefficients developed to estimate power

factor for all representative units at each efficiency level analyzed by DOE.

Ta ble 7.2

. 2 Polynomial Equation Coefficients for Power Factor vs. Loading Relationship

Representative

Unit CSL A B C D

1 0 0.036 2.055

- 1.856 0.595

1 0.034 2.053

- 1.858 0.592

2 0.066 1.664

- 1.314 0.374

3 0.071 2.140

- 2.034 0.663

4 0.074 2.140

- 2.025 0.661

5 0.071 2.140

- 2.034 0.663

2 0 0.076 2.143

- 2.023 0.664

1 0.034 2.053

- 1.858 0.592

2 0.034 2.053

- 1.858 0.592

3 0.075 1.977

- 1.817 0.5755 4 0.047 2.332

- 2.387 0.794

5 0.047 2.332

- 2.387 0.794

3 0 0.036 2.055

- 1.856 0.595

1 0.034 2.053

- 1.858 0.592

2 0.074 2.140

- 2.025 0.661

3 0.036 2.055

- 1.856 0.595

4 0.043 2.492

- 2.625 0.900

5 0.038 2.487

- 2.630 0.895

4 0 0.033 1.612

- 1.276 0.381

1 0.040 0.860

- 0.269

- 0.012

2 0.059 1.324

- 0.831 0.177

3 0.077 1.746

- 1.453 0.420

5 0 0.074 2.140

- 2.025 0.661

1 0.044 1.925

- 1.704 0.515

2 0.044 1.925

- 1.704 0.515

3 0.050 2.401

- 2.506 0.849

6 0 0.034 2.053

- 1.858 0.592

1 0.066 1.664

- 1.314 0.374

2 0.071 2.140

- 2.034 0.663

3 0.074 2.140

- 2.025 0.661

4 0.071 2.140

- 2.034 0.663

7 0 0.034 2.053

- 1.858 0.592

1 0.034 2.053

- 1.858 0.592

2 0.075 1.977

- 1.817 0.575

3 0.047 2.332

- 2.387 0.794

4 0.047 2.332

- 2.387 0.794

8 0 0.034 2.053

- 1.858 0.592

1 0.074 2.140

- 2.025 0.661

2 0.036 2.055

- 1.856 0.595

3 0.043 2.492

- 2.625 0.900

4 0.038 2.487

- 2.630 0.895

7.2.4 Motor Applications

The annual operating hours and loading of motors depend on the sector (i.e., industry,

agriculture, and commercial), motor size (in horsepower), and end

- use application (e.g., pump).

DOE estimated the share of motors in each type of application depending o n the National

Electrical Manufacturers Association (NEMA) design and size of the motor, and used a

distribution of motors across sectors by motor size. DOE drew upon several data sources to

develop a model of the applications for which motors covered in t his analysis are used.

Six motor applications (air compressors, fans, pumps, material handling and processing,

fire pumps, and others) were selected as representative applications based on a previous DOE

study (DOE

- ITP study) 3 and a database of motor nameplate and field measurement data

compiled by the Washington State University (WSU) Extension Energy Program, Applied6 Proactive Technologies (APT), and New York State Energy Research and Development

Authority (NYSERDA) 4 (“WSU/NYSERDA database”) a

. The tables below summarize the

distribution of NEMA Design A and B motors ( Table 7.2

. 3 ), and NEMA Design C motors

( Table 7.2

. 4 ) across applications by horsepower range in the industria l sector. No sufficient data

were available to develop similar estimates in the commercial or agricultural sector and, instead,

the estimates in the industrial sector were used as an approximation.

Table 7.2

. 3 Distribution of Motors by Application for NEMA Design A and B Motors (in

percent)

Horsepower (hp) range

Application 1

- 5 6

- 20 21

- 50 51

- 100 101

- 200 201

- 500 all

hp

Air Compressor 1. 8 1.3 2. 2 5.6 5. 4 8.3 2. 2

Fans 22. 5 24.9 26. 6 25.7 18.9 2 1.7 24. 0

Pumps 22. 3 31. 6 3 3.0 34. 2 3 6.0 2 5.5 28. 5

Material Handling and Processing 12. 0 9.4 6.8 1 0.6 7.8 7.6 10. 0

Other 4 1.4 32. 8 3 1.4 23. 9 31. 9 3 6.9 35. 3

Fire Pumps 0.0 0.0 0.0 0.0 0.0 0.0 0.0

Table 7.2

. 4 Distribution of Motors by A pplication f or NEMA Design C Motors (in

percent)

Horsepower (hp) range

Application 1

- 5 6

- 20 21

- 50 51

- 100 101

- 200 all hp

Air Compressor 0.0 0.0 0.0 0.0 0.0 0.0

Fans 25.0 11.1 0.0 11.1 10.3 10.3

Pumps 0.0 0.0 28.6 0.0 6.9 6.9

Material Handling and Processing 25.0 11.1 14.3 11.1 13.8 13.8

Other 50.0 77.8 57.1 77.8 69.0 69.0

Fire Pumps 0.0 0.0 0.0 0.0 0.0 0.0

The distribution of motors across sectors by motor size was extracted from an Easton

Consultants report 5 which provides the distribution of alternating

- current integral

- horsepower

motors by horsepower across various sectors. DOE adjusted the distribution across sectors to

only account for three

- digit NEMA frame size motors assuming that two

- digit NEMA frame size

a The motors database comprised of information gathered by WSU and APT during 123 industrial motor surveys or

assessments: 11 motor assessments were conducted between 2005 and 2011 and occurred in industrial plants; 112

industrial motor surveys were conduct ed between 2005 and 2011 and were funded by NYSERDA and conducted in

New York State.7 motors account for 30 percent of total integral motors below 5 hp and are primarily used in the

commercial sector. ( Table 7.2

. 5 )

Table 7.2

. 5 Motor Distribution across Sector by Mo tor Size

Horsepower

range Industry

% Agriculture

% Commercial

%

1

- 5 37 0 63

6

- 20 26 0 74

21

- 50 26 0 74

51

- 100 63 7 30

101

- 200 76 3 21

201

- 500 69 3 28

7.2.5 Loading

To calculate the annual kWh use at each efficiency level in each equipment class, DOE

used the losses versus load curves from the engineering analysis ( Table 7.2

. 1 ) , along with

estimates of motor operating hours and average loading.

T he average mot or loading mainly depends on the motor’s end

- use application (e.g.

, fan,

pump) and sector (e.g.

, industrial). In the industrial sector, the DOE

- ITP study shows that , for a

specific application, loading does not vary significantly across horsepower ranges

. DOE

estimated application

- specific average loading based on approximately 15,000 field

measurements provided by the WSU/NYSERDA database. A statistical distribution to

characterize variability in the field was also extracted from the WSU/NYSERDA database. Table

7.2

. 6 presents the average motor loading by applications in the industrial sector. Because

sufficient data were not available, the same average loading values and statistical distribution

were used in the commercial and agricultural sectors.

Table 7.2

. 6 Average Motor Loading by Application

Application Loading %

Air compressors 0.70

Fans 0.60

Pumps 0.68

Material Handling and Processing 0.48

Other 0.71

Fire Pumps 0.62

7.2.6 Motor Hours of Operation/Duty Factor

DOE estimated average annual operating hours by sector, application, and horsepower

ranges and developed statistical distributions to use in its Monte Carlo analysis (the Monte Carlo

analysis is described in TSD chapter 8).8 For the industrial sector, DOE use d the WSU/NYSERDA database to determine average

annual operating hours by application and horsepower ranges and statistical distributions . For

example, Figure 7.2

. 1 s hows the cumulative form of the discrete distributions for motors

between 2 1 and 50 horsepower in various applications.

0.0% 20.0% 40.0% 60.0% 80.0% 100.0% 120.0%

0 2000 4000 6000 8000Cumulative Distribution

Operating Hours (Hours) Air compressors

Fans

Pumps

Material Handling

and Processing

Others

Fire Pump

Figure 7.2

. 1 Cumulative D istribution for 2 1

- 50 Horsepower M otors by A pplications in

I ndustry S ector.

For the commercial and agricultural sectors, DOE derived estimates of average operating

hours by application and horsepower range from various sources : a p resentation by Richard A.

Peterson 6

, an a rticle by Michae l Gallaher et al

. 7

, the Regional Technical Forum 8 , DOE’s own

analysis on classification and evaluation of electric motors and pump 9

, an Electric Power

Research Institute ( EPRI ) report 10 , and a DOE report by Arthur D. Littl e 11 . For fire pumps, DOE

assumed a u niform distribution between 0.5 hours (based on comments from interested parties)

to 6 hours.

Table 7.2

. 7 displays the average hours of motor operation by application and motor sizes

for the industrial, commercial, and agricultural sectors.9 Table 7.2

. 7 Average Motor Operating Hours by Application and Horsepower Range

Horsepower (hp) range

1

- 5 6

- 20 21

- 50 51

- 100 101

- 200 201

- 500

Industry

Air Compressors 4,647 5,033 4,578 5,337 6,226 6,349

Fans 6,193 6,490 5,849 6,975 7,163 8,015

Pumps 6,028 6,773 6,972 6,869 6,985 6,934

Material Handling 6,486 6,284 6,518 6,315 7,172 6,116

Other 6,571 6,274 6,814 7,128 7,337 7,528

Fire Pump 13 366 366 3,848 4,411 4,411

Commercial

Air Compressors 1,000 1,200 1,500 1,500 1,500 1,500

Fans 3,000 3,300 3,600 3,900 4,200 4,500

Pumps 1,500 1,650 1,800 1,950 2,100 2,250

Material Handling 1,959 2,165 2,380 2,567 2,753 2,939

Other 1,959 2,165 2,380 2,567 2,753 2,939

Fire Pump 0.5

- 6 0.5

- 6 0.5

- 6 0.5

- 6 0.5

- 6 0.5

- 6

Agriculture

Air Compressors 1,901 1,901 1,901 1,901 1,901 1,901

Fans 4,800 4,800 4,800 4,800 4,800 4,800

Pumps 1,800 1,800 1,800 1,900 2,000 2,000

Material Handling 1,500 1,500 1,500 1,500 1,500 1,500

Other 1,901 1,901 1,901 1,901 1,901 1,901

Fire Pump 0.5

- 6 0.5

- 6 0.5

- 6 0.5

- 6 0.5

- 6 0.5

- 6

7.3 ANNUAL ENERGY USE

Depending on the hours of operation, the loading, and the efficiency of the motor (which

varies with the standard level), the annual energy use varies both by efficiency level and from

motor to motor. The annual energy use is calculated using t he following expression:

op H L HP E × ×

=

η

where:



### E = energy use,



### HP

= horsepower of the motor, or motor capacity,

L = motor loading as a fraction of rated power in percent



### η = operating efficiency, and

op 

### H

= motor operating hours.10 Table 7.3

. 1 shows the results of the energy use analysis for the eight representative units

at each considered energy efficiency level. Results are given for baseline units (CSL 0) and the

three candidate standard levels (CSLs) being considered for motors.

Table 7.3

. 1 Average Annual Energy Consumption by Efficiency Level for Representative

Units

Rep

. Unit Description kilowatt

- hours per year

CSL 0 CSL 1 CSL 2 CSL 3 CSL 4 CSL 5

1 Design B, T

- f rame, 5

hp* , 4 poles, e nclosed 10,448 9,869 9,691 9,616 9,567 9,487

2 Design B, T

- f rame, 30

hp , 4 poles, e nclosed 57,642 55,912 55,021 54,492 54,326 54,326

3 Design B, T

- f rame, 75

hp , 4 poles, e nclosed 204,834 202,540 198,496 197,697 197,194 196,604

4 Design C, T

- f rame, 5

hp , 4 poles, e nclosed 9,987 9,808 9,738 9,630

- -

5 Design C, T

- f rame, 50

hp , 4 poles, e nclosed 89,523 88,507 88,119 87,444

- -

6 Fire p ump, 5 hp , 4

poles, enclosed 19.6 19.2 19.1 19.0 18.8

-

7 Fire p ump, 30 hp , 4

poles, enclosed 1,601 1,577 1,562 1,558 1,558

-

8 Fire p ump, 75 hp , 4

poles, enclosed 97,791 95,934 95,554 95,313 95,033

-

* hp = horsepower.11 REFERENCES

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Information Guide for General Purpose Industrial AC Small and Medium Squirrel

- Cage

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.

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Economical Considerations of Line

- Start PM Motors Including the Applicability of the

IEC600

- 34

- 2

- 1 Standard , Energy Efficiency in Motor Driven Systems, Alexandria, VA

.

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Market Opportunities Assessment

. Retrieved February 9, 2011 , from

http:// www1.eere.energy.gov/industry/bestpractices/pdfs/mtrmkt.pdf

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http://neea.org/research/reports/E00

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http://www.nwcouncil.org/energy/rtf/measures/ag/IrrgAg_PremiumMotorsFY10v1_2.xls

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Pumps

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Commerical Sectors with High

- Efficiency Electric Motors. Washington, DC: Department of

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