## 6-i 

# CHAPTER 6. ENERGY USE CHARACTERIZATION

TABLE OF CONTENTS

6.1 INTRODUCTION ........................................................................................................... 6-1 6.2 ENERGY USE ANALYSIS FOR SMALL ELECTRIC MOTORS ............................... 6-1 6.2.1 Introduction .................................................................................................... 6-1 6.2.2 Motor Losses .................................................................................................. 6-1 6.2.3 Reactive Power .............................................................................................. 6-2 6.2.4 Motor Applications ........................................................................................ 6-4 6.2.5 Loading .......................................................................................................... 6-5 6.2.6 Motor Hours of Operation/Duty Factor ......................................................... 6-5 6.3 ANNUAL ENERGY USE

............................................................................................... 6-8

6-7

6-8

6-6

6-7 LIST OF TABLES

Table 6.2.1 Losses vs. Loading, Polyphase Motors................................................................ 6-2 Table 6.2.2 Losses vs. Loading, Capacito r-Start Induction Run Motors ................................ 6-2 Table 6.2.3 Losses vs. Loading, Capacito r-Start Capacitor-Run Motors ............................... 6-2 Table 6.2.4 Power Factor vs. Loading, Polyphase Motors ..................................................... 6-3 Table 6.2.5 Power Factor vs. Loading, Cap acitor-Start Induction-Run Motors ..................... 6-4 Table 6.2.6 Power Factor vs. Loading, Capac itor-Start Capacitor-Run Motors ..................... 6-4 Table 6.2.7 Application Shares by Equipment Type .............................................................. 6-5 Table 6.2.8 Motor Loading by Application ............................................................................ 6-5 Table 6.2.9 Median and Average Hours of Mo tor Operation by Application

........................ Table 6.3.1 Average Annual Electricity Use by Effi ciency Level for Small Electric Motors

..................................................................................................................

LIST OF FIGURES Figure 6.2.1 Comparison of DOE’s Duty Fact or Model with Nadel et al.

.............................. Figure 6.2.2 DOE Estimates of Duty Factor Distributions for Motors in Analyzed Applications

.........................................................................................................

## 6-1 

# CHAPTER 6. ENERGY USE CHARACTERIZATION

6.1 INTRODUCTION A key component of the life-cycle cost (L CC) and payback period (PBP) calculations described in chapter 8 is the savings in operati ng cost customers would realize from more energy efficient products. Energy costs are the most si gnificant component of customer operating costs, with maintenance and repair co sts the other contributors. 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 annual energy use of small electric motors.

6.2 ENERGY USE ANALYSIS FOR SMALL ELECTRIC MOTORS

6.2.1 Introduction The energy use by small electric motors derives from three components: energy converted to useful mechanical shaft power, motor losses, an d reactive power. Motor losses consist of I 2 

# R losses (both stator and rotor), core lo sses, stray 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 losses are also dependent upon loading. DOE models the I 2 

# R losses and stray losses as load-dependent losses.

6.2.2 Motor Losses

DOE obtained estimates of motor losses from estimates of the performance of the specific motor designs that it developed in th e engineering analysis. To determine the annual energy use in kilowatt-hours (kWh), DOE adjusts the full-load losses using the estimate of the motor duty factor (hours of operation per year) and loading. Tables 6.2.1 through 6.2.3 present the losses as a function of loading for each moto r type and for each efficiency level analyzed by DOE. These efficiency levels correspond with de signs analyzed in the Engineering Analysis. Total annual losses are proportional to duty factor. Annual energy losses Eloss 

# is represented by the following equation:

Eloss 

# = H op 

# × Loss(L )

Where:

Eloss 

# = annual energy consumed by motor losses; H op 

# = the annual operating hours, also known as the duty factor; Loss(L ) = the losses of the motor at loading L ; and L = motor loading as a fraction of rated power.

## 6-2 

# Table 6.2.1 Losses vs. Loading, Polyphase Motors Losses (W) vs. Loading (%) – Polyphase, 1 hp
EL Space Constrained Not Space Constrained 0% 25% 50% 75% 100% 125% 150% 0% 25% 50% 75% 100% 125% 150% 0 123.7 132.7 150.8 179.6 221.5 279.7 361.4 123.7 132.7 150.8 179.6 221.5 279.7 361.4 1 119.5 127.7 143.1 167.3 202.3 249.6 312.3 119.5 127.7 143.1 167.3 202.3 249.6 312.3 2 107.3 115.4 130.5 153.6 187.2 232.2 291.2 107.3 115.4 130.5 153.6 187.2 232.2 291.2 3 87.8 95.8 111.1 133.3 168.3 213.9 274.2 87.8 95.8 111.1 133.3 168.3 213.9 274.2 4 84.1 91.8 106.1 127.2 158.6 199.4 253.1 84.1 91.8 106.1 127.2 158.6 199.4 253.1 5 50.9 58.7 73.7 95.3 129.5 173.7 231.9 54.9 62.6 77.1 98.0 130.2 171.6 226.3 6 46.2 53.7 66.7 85.5 114.0 150.1 197.0 51.1 58.5 71.5 91.0 117.8 153.3 199.0 7 30.4 37.9 51.0 69.5 98.3 134.5 181.4 45.6 52.0 62.3 77.0 96.7 122.7 152.4



# Table 6.2.2 Losses vs. Loading, Capacitor-Start Induction Run Motors Losses (W) vs. Loading (%) – Capacitor-Start Induction-Run, 0.5 hp EL Space Constrained Not Space Constrained 0% 25% 50% 75% 100% 125% 150% 0% 25% 50% 75% 100% 125% 150% 0 227.3 221.3 230.4 247.0 273.4 312.6 369.0 227.3 221.3 230.4 247.0 273.4 312.6 369.0 1 207.3 201.5 210.8 227.5 253.8 292.3 347.7 207.3 201.5 210.8 227.5 253.8 292.3 347.7 2 176.2 178.7 187.9 204.0 228.5 264.0 314.1 176.2 178.7 187.9 204.0 228.5 264.0 314.1 3 157.1 157.3 166.9 183.4 208.9 245.7 299.0 157.1 157.3 166.9 183.4 208.9 245.7 299.0 4 120.5 119.1 128.9 145.5 171.2 208.6 262.4 124.3 126.6 134.9 150.0 171.6 202.5 245.8 5 114.8 109.6 117.7 128.7 149.4 177.4 213.9 114.8 109.6 117.7 128.7 149.4 177.4 213.9 6 92.0 91.8 100.8 115.4 137.1 168.6 214.6 101.3 99.4 107.3 118.8 137.3 161.3 194.8 7 65.0 63.3 72.7 88.0 110.8 144.1 192.3 75.8 77.8 84.1 94.5 109.5 129.9 156.7



# Table 6.2.3 Losses vs. Loading, Capacitor-Start Capacitor-Run Motors Losses (W) vs. Loading (%) – Capacitor-Start Capacitor-Run, 0.75 hp EL Space Constrained Not Space Constrained 0% 25% 50% 75% 100% 125% 150% 0% 25% 50% 75% 100% 125% 150% 0 157.3 157.9 170.3 193.2 228.6 281.4 358.9 157.3 157.9 170.3 193.2 228.6 281.4 358.9 1 155.5 144.6 151.9 167.2 192.4 231.8 291.4 155.5 144.6 151.9 167.2 192.4 231.8 291.4 2 119.5 108.6 115.7 130.3 154.7 192.9 251.9 107.4 98.1 105.9 124.3 153.2 201.2 276.1 3 112.6 98.9 103.8 115.4 135.7 171.3 221.1 87.7 79.5 88.4 106.3 135.5 180.3 248.9 4 119.5 102.8 103.3 109.6 124.0 153.3 195.4 117.3 95.5 97.8 107.2 124.8 152.5 197.0 5 134.0 98.4 102.1 106.1 115.9 133.0 159.3 118.5 89.4 94.1 101.7 116.2 139.2 173.1 6 114.6 100.6 97.8 102.5 116.7 144.0 190.2 117.6 90.5 92.3 98.1 111.1 133.5 170.6 7 113.0 82.2 84.2 88.7 100.0 119.7 150.0 102.0 71.8 75.4 81.4 94.1 115.0 146.3 8 79.1 50.1 56.3 65.5 81.8 107.3 144.0 88.6 64.9 66.0 71.9 87.5 113.8 158.4



# 6.2.3 Reactive Power In an alternating current pow er system, the reactive power is the root mean square (RMS) voltage times the RMS current, multiplied by the sine of the phase difference between the voltage and the current. Reactive power occurs when the inductance or capacitance of the load

## 6-3 

# 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 an d 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 ha s three components: real power ( P ), measured in watts (W); apparent power ( S ), measured in volt-amperes (VA); and reactive power ( Q ), measured in reactive volt-amperes (VAr). Th e power factor is defined as P /S . In the case of a perfectly sinusoidal waveform, P , Q and S can be expressed as vectors thatform 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) Where: Q = reactive power in reactive volt-amperes; P = real power in watts; PF = the motor’s power factor; DOE obtained motor power factor as a functi on of motor loading from estimates of the performance of the specific motor designs that it developed in the engine ering analysis. Tables 6.2.4 through 6.2.6 present the power factor as a func tion of loading for each motor type and for each efficiency level analyzed by DOE.

Table 6.2.4 Power Factor vs. Loading, Polyphase Motors Power Factor (kW/kVAr) vs. Loading (%) – Polyphase, 1 hp
EL Space Constrained Not Space Constrained 0% 25% 50% 75% 100% 125% 150% 0% 25% 50% 75% 100% 125% 150% 0 0.14 0.33 0.50 0.63 0.72 0.78 0.82 0.14 0.33 0.50 0.63 0.72 0.78 0.82 1 0.13 0.33 0.50 0.63 0.71 0.77 0.81 0.13 0.33 0.50 0.63 0.71 0.77 0.81 2 0.12 0.33 0.50 0.63 0.72 0.77 0.81 0.12 0.33 0.50 0.63 0.72 0.77 0.81 3 0.12 0.35 0.54 0.67 0.74 0.79 0.82 0.12 0.35 0.54 0.67 0.74 0.79 0.82 4 0.12 0.35 0.53 0.66 0.74 0.79 0.82 0.12 0.35 0.53 0.66 0.74 0.79 0.82 5 0.07 0.30 0.49 0.64 0.72 0.77 0.81 0.08 0.33 0.53 0.67 0.74 0.79 0.82 6 0.06 0.30 0.50 0.64 0.72 0.78 0.81 0.07 0.33 0.53 0.66 0.74 0.79 0.82 7 0.04 0.28 0.49 0.63 0.72 0.77 0.80 0.06 0.31 0.51 0.64 0.73 0.78 0.82

## 6-4 

# Table 6.2.5 Power Factor vs. Loading, Capacitor-Start Induction-Run Motors Power Factor (kW/kVAr) vs. Loading (%) – Capacitor-Start Induction-Run, 0.5 hp
EL Space Constrained Not Space Constrained 0% 25% 50% 75% 100% 125% 150% 0% 25% 50% 75% 100% 125% 150% 0 0.24 0.33 0.43 0.52 0.59 0.66 0.71 0.24 0.33 0.43 0.52 0.59 0.66 0.71 1 0.23 0.32 0.42 0.51 0.59 0.66 0.71 0.23 0.32 0.42 0.51 0.59 0.66 0.71 2 0.21 0.32 0.42 0.51 0.59 0.66 0.71 0.21 0.32 0.42 0.51 0.59 0.66 0.71 3 0.21 0.33 0.44 0.54 0.62 0.68 0.73 0.21 0.33 0.44 0.54 0.62 0.68 0.73 4 0.17 0.30 0.42 0.53 0.61 0.68 0.73 0.21 0.35 0.49 0.59 0.67 0.73 0.77 5 0.16 0.28 0.41 0.52 0.60 0.66 0.71 0.16 0.28 0.41 0.52 0.60 0.66 0.71 6 0.16 0.29 0.41 0.52 0.61 0.68 0.73 0.16 0.30 0.43 0.54 0.62 0.69 0.73 7 0.13 0.30 0.45 0.58 0.67 0.73 0.77 0.14 0.31 0.46 0.57 0.66 0.71 0.75



# Table 6.2.6 Power Factor vs. Loading, Capacitor-Start Capacitor-Run Motors Power Factor (kW/kVAr) vs. Loading (%) – Capacitor-Start Capa citor-Run, 0.75 hp
EL Space Constrained Not Space Constrained 0% 25% 50% 75% 100% 125% 150% 0% 25% 50% 75% 100% 125% 150% 0 0.19 0.35 0.49 0.60 0.68 0.74 0.78 0.19 0.35 0.49 0.60 0.68 0.74 0.78 1 0.26 0.44 0.60 0.70 0.77 0.81 0.84 0.26 0.44 0.60 0.70 0.77 0.81 0.84 2 0.20 0.39 0.55 0.67 0.75 0.80 0.83 0.27 0.52 0.70 0.79 0.84 0.86 0.87 3 0.23 0.45 0.62 0.74 0.80 0.84 0.86 0.22 0.49 0.68 0.78 0.83 0.86 0.86 4 0.43 0.69 0.82 0.88 0.91 0.92 0.92 0.78 0.92 0.95 0.96 0.96 0.95 0.94 5 0.53 0.79 0.85 0.90 0.92 0.93 0.93 0.76 0.92 0.94 0.96 0.96 0.95 0.94 6 0.99 1.00 1.00 1.00 0.99 0.99 0.97 0.97 1.00 1.00 1.00 0.99 0.98 0.97 7 0.98 0.99 0.99 0.99 0.99 0.98 0.97 0.86 0.97 0.97 0.98 0.97 0.97 0.96 8 0.32 0.69 0.79 0.87 0.90 0.92 0.92 0.77 0.96 0.99 1.00 1.00 0.99 0.97



# 6.2.4 Motor Applications The annual operating hours and loading of small electric motors depends on the application. For different types of motors, the market shares of differentmotor applications can vary. As described in more detail in chapter 9 of this TSD, DOE drew upon several data sources to develop a model of the applications for which motors covered in this analysis are used: data collected by Easton Consultants in the preparation of the Small Motors Determination Analysis, 2 

# DOE’s own analysis in the Determination and Framework stages, 3 , 4 

# U.S. Census reports, comments from interested parties (both written and at the preliminary analysis public meeting), 5 

# and interviews with expe rts in motor OEM industries. 6



# Table 6.2.7 summarizes the market shares fo r shipments of small electric motors by application based on DOE’s analys is of the available data.

## 6-5 

# Table 6.2.7 Application Shares by Equipment Category Equipment Category No. Application Polyphase CSIR CSCR

1 Air and gas compressors 17.3% 14.9% 14.9% 2 Conveyors 13.3% 11.9% 11.9% 3 General industrial machinery 11.3% 12.5% 12.5%

4 Industrial and commercial fans and blowers 7.3% 6.9% 6.9%

5 Pumps and pumping equipment 50.7% 53.7% 53.7% TOTAL 100% 100% 100%



# 6.2.5 Loading

To calculate the annual kWh use at each effi ciency level in each equipment class, DOE used the efficiencies and losses from the engin eering analysis, along with estimates of operating hours. Since the losses of a motor depend on th e motor loading, DOE estimated average motor loading in order to look-up the motor losses fr om the engineering data. DOE obtained motor loading as a function of motor application from the determination analysis for the applications that use equipment containing covered small electric motors, as shown in Table 6.2.8. DOE assumed that the motor loading distribution took the form of a normal distribution, centered on the average value, with a sta ndard deviation equal to one fi fth of the average loading.

Table 6.2.8 Motor Loading by Application No. Application Loading

1 Air and gas compressors 85% 2 Conveyors 50% 3 General industrial machinery 70% 4 Industrial and commercial fans and blowers 80% 5 Pumps and pumping equipment 65%



# 6.2.6 Motor Hours of Operation/Duty Factor DOE developed estimated distributions for the duty factor of motors for each application. See chapter 9 for a discussion of the applications that DOE analyz ed for covered motors, and the fraction of small electric motor shipments for eachapplication. DOE estimated the distribution of motor duty factors from data referenced in Nadel et al

. 7 

# DOE approximated this distribution as a decaying exponential curve plus a percentage of mo tors that operate 8760 hours per year (that is,

# 100% of the time). Figure 6.2.1 shows the correspondence betweenthis simple model and the data referenced in Nadel et al

.

0.00% 10.00% 20.00% 30.00% 40.00% 50.00% 60.00% 70.00% 80.00% 90.00% 100.00%

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 

### Duty Factor (Hours per year)Cumulative Percentage of Motors



### Nadel et al, 1-5 HP data DOE Model, Small Motors



# Figure 6.2.1 Comparison of DOE’s Duty Factor Model with Nadel et al. DOE then adapted this model for each of the five application areas analyzed as part of this rulemaking: pumps; conveyor, material handl ing, and packaging systems; air compressors; blowers and fans; and general industrial machiner y. DOE used estimates for average and median hours of operation based on the 2006 Determination Analysis, along with comments from interested parties on the Preliminary Analysis, to develop distributions for each application.

Table 6.2.9 shows DOE’s estimated median and mean hours of operation in each application, along with the per centage of motors that operate 100% of the time. Figure 6.2.2 shows the cumulative form of the discrete distri butions DOE used in it s Monte Carlo analysis. (The Monte Carlo analysis is described in chapter 8.)

6-6

# Table 6.2.9 Median and Average Hours of Motor Operation by Application Application Median Annual Hours of Operation Average Annual Hours of Operation 100% Run Time Motors (%) Compressors 375 600 0 Conveyors 2000 3000 8 General Industry 1200 2000 4 Fans and Blowers 2825 4500 40 Pumps 1850 3000 12

0.00% 20.00% 40.00% 60.00% 80.00% 100.00%

0 1000 2000 3000 4000 5000 6000 7000 8000 9000 

### Duty Factor (Hours per Year)Cumulative % of Motors



### Compressors Conveyors Pumps

Fans & Blowers General Industry



# Figure 6.2.2 DOE Estimates of Duty Factor Distributions for Motors in Analyzed Applications

6-7

## 6-8 

# 6.3 ANNUAL ENERGY USE Depending on the hours of operation and the loading (which are functions of the application) and the efficiency of the motor (whi ch varies with the standard level), the annual energy use varies both by efficiency level and from motor to motor. Table 6.3.1 shows the average annual energy use as a function of effici ency level for the thr ee representative product classes. In the table, the rate d capacity of the repres entative motor from the product class is in parentheses. The average energy use estimates are from a calculation for a nationally representative distributi on of motor applications, include bothmotor losses and the shaft power provided by the motor as described in chapter 8 of this TSD.

Table 6.3.1 Average Annual Electricity Use by E fficiency Level for Small Electric Motors Polyphase (1 hp) CSIR (0.5 hp) CSCR (0.75 hp) Efficiency Level Efficiency (%) Energy Use (kWh/yr) Efficiency (%) Energy Use (kWh/yr) Efficiency (%) Energy Use (kWh/yr) Baseline 77.2 1763 57.7 1277 71.0 1451 1 78.7 1734 59.5 1226 74.3 1389 2 80.0 1698 62.0 1164 78.3 1278 3 81.6 1645 64.2 1110 80.3 1233 4 82.5 1629 68.5 1020 81.6 1239 5 85.2 1549 71.2 971 82.7 1226 6 86.7 1529 73.0 942 83.7 1219 7 88.3 1494 77.0 877 85.4 1175 8 NA NA NA NA 87.3 1144

## 6-9 

# REFERENCES

1 

# National Electrical Manufacturers A ssociation, NEMA Standards Publication: Information Guide for General Purpose Industrial AC Small and Me dium Squirrel-Cage Inducation Motor Standards, NEMA, 1300 North 17 th

# Street, Suite 1847, Rosslyn, VA 22209, 2002. 2 

# The work by Easton Consultants is summarized in Appendix B of Determination Analysis Technical Support Document: Analys is of Energy Conservation Standards for Small Electric Motors , June 2006 <http://www1.eere.energy.gov/buildings/appliance_standards/commercial/pdfs/small_mo tors_tsd.pdf> 3 

# Determination Analysis Technical Support Do cument: Analysis of Energy Conservation Standards for Small Electric Motors , June 2006 <http://www1.eere.energy.gov/buildings/appliance_standards/commercial/pdfs/small_mo tors_tsd.pdf> 4 

# Energy Conservation Standards Rulemaki ng Framework Document for Small Electric Motors <http://www1.eere.energy.gov/buildings/appliance_standards/commercial/pdfs/small_mo tors_framework_073007.pdf> 5 

# Transcript of Public Meeting on Energy Conservation Standards for Small Electric Motors, January 30, 2009, <http://www1.eere.energy.gov/buildings/appliance_ standards/commercial/pdfs/transcript _small_motors_standards_meeting.pdf> 6 

# Joe Evans. PentAir Water Pumps, personal communication, March 5, 2009. 7 

# Nadel, S. ; Elliott, R.N. ; Shepard, M. ; Gr eenberg, S. ; Katz, G. ; Almeida, A. de, Energy-efficient motor systems: A handbook on technology, programs, and policy opportunities, 2nd edition. 2000. American Council for an Energy-Efficient Economy, Washington, DC (US).