10 C.F.R. § 430 app B to Subpart B of Part 431
Note: Manufacturers of electric motors subject to energy conservation standards in § 431.25 must test in accordance with this appendix.
For any other electric motor that is not currently covered by the energy conservation standards at § 431.25 , manufacturers of this equipment must test in accordance with this appendix 180 days after the effective date of the final rule adopting energy conservation standards for such motor. For any other electric motor that is not currently covered by the energy conservation standards at § 431.25 , manufacturers choosing to make any representations respecting of energy efficiency for such motors must test in accordance with this appendix.
0. Incorporation by Reference
In § 431.15 , DOE incorporated by reference the entire standard for CSA C390-10, CSA C747-09, IEC 60034-1:2010, IEC 60034-2-1:2014, IEC 60051-1:2016, IEC 61800-9-2:2017, IEEE 112-2017, IEEE 114-2010, and NEMA MG 1-2016; however, only enumerated provisions of those documents are applicable as follows. In cases where there is a conflict, the language of this appendix takes precedence over those documents. Any subsequent amendment to a referenced document by the standard-setting organization will not affect the test procedure in this appendix, unless and until the test procedure is amended by DOE.
0.1. CSA C390-10
(a) Section 1.3 "Scope," as specified in sections 2.1.1 and 2.3.3.2 of this appendix;
(b) Section 3.1 "Definitions," as specified in sections 2.1.1 and 2.3.3.2 of this appendix;
(c) Section 5 "General test requirements-Measurements," as specified in sections 2.1.1 and 2.3.3.2 of this appendix;
(d) Section 7 "Test method," as specified in sections 2.1.1 and 2.3.3.2 of this appendix;
(e) Table 1 "Resistance measurement time delay," as specified in sections 2.1.1 and 2.3.3.2 of this appendix;
(f) Annex B "Linear regression analysis," as specified in sections 2.1.1 and 2.3.3.2 of this appendix; and
(g) Annex C "Procedure for correction of dynamometer torque readings" as specified in sections 2.1.1 and 2.3.3.2 of this appendix.
0.2. CSA C747-09
(a) Section 1.6 "Scope" as specified in sections 2.3.1.2 and 2.3.2.2 of this appendix;
(b) Section 3 "Definitions" as specified in sections 2.3.1.2 and 2.3.2.2 of this appendix;
(c) Section 5 "General test requirements" as specified in sections 2.3.1.2 and 2.3.2.2 of this appendix; and
(d) Section 6 "Test method" as specified in sections 2.3.1.2 and 2.3.2.2 of this appendix.
0.3. IEC 60034-1:2010
(a) Section 4.2.1 as specified in section 1.2 of this appendix;
(b) Section 7.2 as specified in sections 2.1.2 , 2.3.1.3 , 2.3.2.3 , and 2.3.3.3 of this appendix;
(c) Section 8.6.2.3.3 as specified in sections 2.1.2 , 2.3.1.3 , 2.3.2.3 , and 2.3.3.3 of this appendix; and
(d) Table 5 as specified in sections 2.1.2 , 2.3.1.3 , 2.3.2.3 , and 2.3.3.3 of this appendix.
0.4. IEC 60034-2-1:2014
(a) Method 2-1-1A (which also includes paragraphs (b) through (f) of this section) as specified in sections 2.3.1.3 and 2.3.2.3 of this appendix;
(b) Method 2-1-1B (which also includes paragraphs (b) through (e), (g), and (i) of this section) as specified in sections 2.1.2 and 2.3.3.3 of this appendix;
(c) Section 3 "Terms and definitions" as specified in sections 2.1.2 , 2.3.1.3 , 2.3.2.3 , 2.3.3.3 , and 2.4.1 of this appendix;
(d) Section 4 "Symbols and abbreviations" as specified in sections 2.1.2 , 2.3.1.3 , 2.3.2.3 , 2.3.3.3 and 2.4.1 of this appendix;
(e) Section 5 "Basic requirements" as specified in sections 2.1.2 , 2.3.1.3 , 2.3.2.3 , 2.3.3.3 , and 2.4.1 of this appendix;
(f) Section 6.1.2 "Method 2-1-1A-Direct measurement of input and output" (except Section 6.1.2.2 , "Test Procedure") as specified in sections 2.3.1.3 and 2.3.2.3 of this appendix;
(g) Section 6.1.3 "Method 2-1-1B-Summations of losses, additional load losses according to the method of residual losses" as specified in sections 2.1.2 and 2.3.3.3 of this appendix; and
(h) Section 7.1 . "Preferred Testing Methods" as specified in section 2.4.1 of this appendix;
(i) Annex D, "Test report template for 2-1-1B" as specified in sections 2.1.2 and 2.3.3.3 of this appendix.
0.5. IEC 60051-1:2016
(a) Section 5.2 as specified in sections 2.1.2 , 2.3.1.3 , 2.3.2.3 , and 2.3.3.3 of this appendix; and
(b) [Reserved].
0.6. IEC 61800-9-2:2017
(a) Section 3 "Terms, definitions, symbols, and abbreviated terms" as specified in sections 2.4.2 and 2.4.3 of this appendix;
(b) Section 7.7.2 , "Input-output measurement of PDS losses" as specified in sections 2.4.2 and 2.4.3 of this appendix;
(c) Section 7.7.3.1 , "General" as specified in sections 2.4.2 and 2.4.3 of this appendix;
(d) Section 7.7.3.2 . "Power analyser and transducers" as specified in sections 2.4.2 and 2.4.3 of this appendix;
(e) Section 7.7.3.3 , "Mechanical Output of the motor" as specified in sections 2.4.2 and 2.4.3 of this appendix;
(f) Section 7.7.3.5 , "PDS loss determination according to input-output method" as specified in sections 2.4.2 and 2.4.3 of this appendix;
(g) Section 7.10 "Testing Conditions for PDS testing" as specified in sections 2.4.2 and 2.4.3 of this appendix.
0.7. IEEE 112-2017
(a) Test Method A (which also includes paragraphs (c) through (g), (i), and (j) of this section) as specified in section 2.3.2.1 of this appendix;
(b) Test Method B (which also includes paragraphs (c) through (f), (h), (k) and (l) of this section) as specified in sections 2.1.3 and 2.3.3.1 of this appendix;
(c) Section 3, "General" as specified in sections 2.1.3 , 2.3.2.1 , and 2.3.3.1 of this appendix;
(d) Section 4, "Measurements" as specified in sections 2.1.3 , 2.3.2.1 , and 2.3.3.1 of this appendix;
(e) Section 5, "Machine losses and tests for losses" as specified in sections 2.1.3 , 2.3.2.1 , and 2.3.3.1 of this appendix;
(f) Section 6.1 , "General" as specified in sections 2.1.3 , 2.3.2.1 , and 2.3.3.1 of this appendix;
(g) Section 6.3 , "Efficiency test method A-Input-output" as specified in section 2.3.2.1 of this appendix;
(h) Section 6.4 , "Efficiency test method B-Input-output" as specified in sections 2.1.3 and 2.3.3.1 of this appendix;
(i) Section 9.2 , "Form A-Method A" as specified in section 2.3.2.1 of this appendix;
(j) Section 9.3 , "Form A2-Method A calculations" as specified in section 2.3.2.1 of this appendix;
(k) Section 9.4 , "Form B-Method B" as specified in sections 2.1.3 , and 2.3.3.1 of this appendix; and
(l) Section 9.5 , "Form B2-Method B calculations" as specified in sections 2.1.3 and 2.3.3.1 of this appendix.
0.8. IEEE 114-2010
(a) Section 3.2 , "Test with load" as specified in section 2.3.1.1 of this appendix;
(b) Section 4, "Testing Facilities as specified in section 2.3.1.1 of this appendix;
(c) Section 5, "Measurements" as specified in section 2.3.1.1 of this appendix;
(d) Section 6, "General" as specified in section 2.3.1.1 of this appendix;
(e) Section 7, "Type of loss" as specified in section 2.3.1.1 of this appendix;
(f) Section 8, "Efficiency and Power Factor" as specified in section 2.3.1.1 of this appendix;
(g) Section 10 "Temperature Tests" as specified in section 2.4.1.1 of this appendix;
(h) Annex A, Section A.3 "Determination of Motor Efficiency" as specified in section 2.4.1.1 of this appendix; and
(i) Annex A, Section A.4 "Explanatory notes for form 3, test data" as specified in section 2.4.1.1 of this appendix.
0.9. NEMA MG 1-2016
(a) Paragraph 1.40.1, "Continuous Rating" as specified in section 1.2 of this appendix;
(b) Paragraph 12.58.1, "Determination of Motor Efficiency and Losses" as specified in the introductory paragraph to section 2.1 of this appendix, and
(c) Paragraph 34.1, "Applicable Motor Efficiency Test Methods" as specified in section 2.2 of this appendix;
(d) Paragraph 34.2.2 "AO Temperature Test Procedure 2-Target Temperature with Airflow" as specified in section 2.2 of this appendix;
(e) Paragraph 34.4, "AO Temperature Test Procedure 2-Target Temperature with Airflow" as specified in section 2.2 of this appendix.
1. Scope and Definitions
1.1 Scope. The test procedure applies to the following categories of electric motors: Electric motors that meet the criteria listed at § 431.25(g) ; Electric motors above 500 horsepower; Small, non-small-electric-motor electric motor; and Electric motors that are synchronous motors; and excludes the following categories of motors: inverter-only electric motors that are air-over electric motors, component sets of an electric motor, liquid-cooled electric motors, and submersible electric motors.
1.2 Definitions. Definitions contained in §§ 431.2 and 431.12 are applicable to this appendix, in addition to the following terms ("MG1" refers to NEMA MG 1-2016 and IEC refers to IEC 60034-1:2010 and IEC 60072-1):
Electric motors above 500 horsepower is defined as an electric motor having a rated horsepower above 500 and up to 750 hp that meets the criteria listed at § 431.25(g) , with the exception of criteria § 431.25(g)(8) .
Small, non-small-electric-motor electric motor ("SNEM" ) means an electric motor that:
(a) Is not a small electric motor, as defined § 431.442 and is not a dedicated-purpose pool pump motor as defined at § 431.483 ;
(b) Is rated for continuous duty (MG 1) operation or for duty type S1 (IEC);
(c) Operates on polyphase or single-phase alternating current 60-hertz (Hz) sinusoidal line power; or is used with an inverter that operates on polyphase or single-phase alternating current 60-hertz (Hz) sinusoidal line power;
(d) Is rated for 600 volts or less;
(e) Is a single-speed induction motor capable of operating without an inverter or is an inverter-only electric motor;
(f) Produces a rated motor horsepower greater than or equal to 0.25 horsepower (0.18 kW); and
(g) Is built in the following frame sizes: any two-, or three-digit NEMA frame size (or IEC metric equivalent) if the motor operates on single-phase power; any two-, or three-digit NEMA frame size (or IEC metric equivalent) if the motor operates on polyphase power, and has a rated motor horsepower less than 1 horsepower (0.75 kW); or a two-digit NEMA frame size (or IEC metric equivalent), if the motor operates on polyphase power, has a rated motor horsepower equal to or greater than 1 horsepower (0.75 kW), and is not an enclosed 56 NEMA frame size (or IEC metric equivalent).
Synchronous Electric Motor means an electric motor that:
(a) Is not a dedicated-purpose pool pump motor as defined at § 431.483 or is not an air-over electric motor;
(b) Is a synchronous electric motor;
(c) Is rated for continuous duty (MG 1) operation or for duty type S1 (IEC);
(d) Operates on polyphase or single-phase alternating current 60-hertz (Hz) sinusoidal line power; or is used with an inverter that operates on polyphase or single-phase alternating current 60-hertz (Hz) sinusoidal line power;
(e) Is rated 600 volts or less;
(f) Produces at least 0.25 hp (0.18 kW) but not greater than 750 hp (559 kW).
2. Test Procedures
2.1. Test Procedures for Electric Motors that meet the criteria listed at § 431.25(g) , and electric motors above 500 horsepower that are capable of operating without an inverter. Air-over electric motors must be tested in accordance with Section 2.2 . Inverter-only electric motors must be tested in accordance with 2.4.
Efficiency and losses must be determined in accordance with NEMA MG 1-2016, Paragraph 12.58.1, "Determination of Motor Efficiency and Losses," or one of the following testing methods:
2.1.1. CSA C390-10 (see section 0.1 of this appendix)
2.1.2. IEC 60034-2-1:2014, Method 2-1-1B (see section 0.4(b) of this appendix). The supply voltage shall be in accordance with Section 7.2 of IEC 60034-1:2010. The measured resistance at the end of the thermal test shall be determined in a similar way to the extrapolation procedure described in Section 8.6.2.3.3 of IEC 60034-1:2010, using the shortest possible time instead of the time interval specified in Table 5 to IEC 60034-1:2010, and extrapolating to zero. The measuring instruments for electrical quantities shall have the equivalent of an accuracy class of 0,2 in case of a direct test and 0,5 in case of an indirect test in accordance with Section 5.2 of IEC 60051-1:2016, or
2.1.3. IEEE 112-2017, Test Method B (see section 0.7(b) of this appendix).
2.2. Test Procedures for Air-Over Electric Motors
Except noted otherwise in section 2.2.1 and 2.2.2 of this appendix, efficiency and losses of air-over electric motors must be determined in accordance with NEMA MG 1-2016 (excluding Paragraph 12.58.1).
2.2.1. The provisions in Paragraph 34.4.1.a.1 of NEMA MG 1-2016 related to the determination of the target temperature for polyphase motors must be replaced by a single target temperature of 75 °C for all insulation classes.
2.2.2. The industry standards listed in Paragraph 34.1 of NEMA MG 1-2016, "Applicable Motor Efficiency Test Methods" must correspond to the versions identified in section 0 of this appendix, specifically IEEE 112-2017, IEEE 114-2010, CSA C390-10, CSA C747-09, and IEC 60034-2-1:2014. In addition, when testing in accordance with IEC 60034-2-1:2014, the additional testing instructions in section 2.1.2 of this appendix apply.
2.3. Test Procedures for SNEMs capable of operating without an inverter. Air-over SNEMs must be tested in accordance with section 2.2 . of this appendix. Inverter-only SNEMs must be tested in accordance with section 2.4 . of this appendix.
2.3.1. The efficiencies and losses of single-phase SNEMs that are not air-over electric motors and are capable of operating without an inverter, are determined using one of the following methods:
2.3.1.1. IEEE 114-2010 (see section 0.8 of this appendix);
2.3.1.2. CSA C747-09 (see section 0.2 of this appendix), or
2.3.1.3. IEC 60034-2-1:2014 Method 2-1-1A (see section 0.4(a) of this appendix),. The supply voltage shall be in accordance with Section 7.2 of IEC 60034-1:2010. The measured resistance at the end of the thermal test shall be determined in a similar way to the extrapolation procedure described in Section 8.6.2.3.3 of IEC 60034-1:2010, using the shortest possible time instead of the time interval specified in Table 5 of IEC 60034-1:2010, and extrapolating to zero. The measuring instruments for electrical quantities shall have the equivalent of an accuracy class of 0,2 in case of a direct test and 0,5 in case of an indirect test in accordance with Section 5.2 of IEC 60051-1:2016.
2.3.1.3.1. Additional IEC 60034-2-1:2014 Method 2-1-1A Torque Measurement Instructions. If using IEC 60034-2-1:2014 Method 2-1-1A to measure motor performance, follow the instructions in section 2.3.1.3.2 . of this appendix, instead of Section 6.1.2.2 of IEC 60034-2-1:2014;
2.3.1.3.2. Couple the machine under test to a load machine. Measure torque using an in-line, shaft-coupled, rotating torque transducer or stationary, stator reaction torque transducer. Operate the machine under test at the rated load until thermal equilibrium is achieved (rate of change 1 K or less per half hour). Record U, I, Pel, n, T, [THETA]c.
2.3.2. The efficiencies and losses of polyphase electric motors considered with rated horsepower less than 1 that are not air-over electric motors, and are capable of operating without an inverter, are determined using one of the following methods:
2.3.2.1. IEEE 112-2017 Test Method A (see section 0.7(a) of this appendix);
2.3.2.2. CSA C747-09 (see section 0.2 of this appendix); or
2.3.2.3. IEC 60034-2-1:2014 Method 2-1-1A (see section 0.4(a) of this appendix). The supply voltage shall be in accordance with Section 7.2 of IEC 60034-1:2010. The measured resistance at the end of the thermal test shall be determined in a similar way to the extrapolation procedure described in Section 8.6.2.3.3 of IEC 60034-1:2010 using the shortest possible time instead of the time interval specified in Table 5 of IEC 60034-1:2010, and extrapolating to zero. The measuring instruments for electrical quantities shall have the equivalent of an accuracy class of 0,2 in case of a direct test and 0,5 in case of an indirect test in accordance with Section 5.2 of IEC 60051-1:2016.
2.3.2.3.1. Additional IEC 60034-2-1:2014 Method 2-1-1A Torque Measurement Instructions. If using IEC 60034-2-1:2014 Method 2-1-1A to measure motor performance, follow the instructions in section 2.3.2.3.2 . of this appendix, instead of Section 6.1.2.2 of IEC 60034-2-1:2014;
2.3.2.3.2. Couple the machine under test to load machine. Measure torque using an in-line shaft-coupled, rotating torque transducer or stationary, stator reaction torque transducer. Operate the machine under test at the rated load until thermal equilibrium is achieved (rate of change 1 K or less per half hour). Record U, I, Pel, n, T, [THETA]c.
2.3.3. The efficiencies and losses of polyphase SNEMs with rated horsepower equal to or greater than 1 that are not air-over electric motors, and are capable of operating without an inverter, are determined using one of the following methods:
2.3.3.1. IEEE 112-2017 Test Method B (see section 0.7(b) of this appendix);
2.3.3.2. CSA C390-10 (see section 0.1 of this appendix); or
2.3.3.3. IEC 60034-2-1:2014 Method 2-1-1B (see section 0.4(b) of this appendix). The supply voltage shall be in accordance with Section 7.2 of IEC 60034-1:2010. The measured resistance at the end of the thermal test shall be determined in a similar way to the extrapolation procedure described in Section 8.6.2.3.3 of IEC 60034-1:2010 using the shortest possible time instead of the time interval specified in Table 5 of IEC 60034-1:2010, and extrapolating to zero. The measuring instruments for electrical quantities shall have the equivalent of an accuracy class of 0,2 in case of a direct test and 0,5 in case of an indirect test in accordance with Section 5.2 of IEC 60051-1:2016.
2.4. Test Procedures for Electric Motors that are Synchronous Motors and Inverter-only Electric Motors
Section 2.4.1 of this appendix applies to electric motors that are synchronous motors that do not require an inverter to operate. Sections 2.4.2 . and 2.4.3. of this appendix apply to electric motors that are synchronous motors and are inverter-only; and to induction electric motors that are inverter-only electric motors.
2.4.1. The efficiencies and losses of electric motors that are synchronous motors that do not require an inverter to operate, are determined in accordance with IEC 60034-2-1:2014, Section 3 "Terms and definitions," Section 4 "Symbols and abbreviations," Section 5 "Basic requirements," and Section 7.1 . "Preferred Testing Methods."
2.4.2. The efficiencies and losses of electric motors (inclusive of the inverter) that are that are inverter-only and do not include an inverter, are determined in accordance with IEC 61800-9-2:2017. Test must be conducted using an inverter that is listed as recommended in the manufacturer's catalog or that is offered for sale with the electric motor. If more than one inverter is available in manufacturer's catalogs or if more than one inverter is offered for sale with the electric motor, test using the least efficient inverter. Record the manufacturer, brand and model number of the inverter used for the test. If there are no inverters specified in the manufacturer catalogs or offered for sale with the electric motor, testing must be conducted using an inverter that meets the criteria described in section 2.4.2.2 . of this appendix.
2.4.2.1. The inverter shall be set up according to the manufacturer's instructional and operational manual included with the product. Manufacturers shall also record switching frequency in Hz, max frequency in Hz, Max output voltage in V, motor control method (i.e., V/f ratio, sensor less vector, etc.), load profile setting (constant torque, variable torque, etc.), and saving energy mode (if used). Deviation from the resulting settings, such as switching frequency or load torque curves for the purpose of optimizing test results shall not be permitted.
2.4.2.2. If there are no inverters specified in the manufacturer catalogs or offered for sale with the electric motor, test with a two-level voltage source inverter. No additional components influencing output voltage or output current shall be installed between the inverter and the motor, except those required for the measuring instruments. For motors with a rated speed up to 3 600 min-1, the switching frequency shall not be higher than 5 kHz. For motors with a rated speed above 3 600 min-1, the switching frequency shall not be higher than 10 kHz. Record the manufacturer, brand and model number of the inverter used for the test.
2.4.3. The efficiencies and losses of electric motors (inclusive of the inverter) that are inverter-only and include an inverter are determined in accordance with IEC 61800-9-2:2017.
2.4.3.1. The inverter shall be set up according to the manufacturer's instructional and operational manual included with the product. Manufacturers shall also record switching frequency in Hz, max frequency in Hz, Max output voltage in V, motor control method (i.e., V/f ratio, sensor less vector, etc.), load profile setting (constant torque, variable torque, etc.), and saving energy mode (if used). Deviation from the resulting settings, such as switching frequency or load torque curves for the purpose of optimizing test results shall not be permitted.
3. Procedures for the Testing of Certain Electric Motor Categories
Prior to testing according to section 2 of this appendix, each basic model of the electric motor categories listed below must be set up in accordance with the instructions of this section to ensure consistent test results. These steps are designed to enable a motor to be attached to a dynamometer and run continuously for testing purposes. For the purposes of this appendix, a "standard bearing" is a 600- or 6000-series, either open or grease-lubricated double-shielded, single-row, deep groove, radial ball bearing.
3.1. Brake Electric Motors:
Brake electric motors shall be tested with the brake component powered separately from the motor such that it does not activate during testing. Additionally, for any 10-minute period during the test and while the brake is being powered such that it remains disengaged from the motor shaft, record the power consumed (i.e., watts). Only power used to drive the motor is to be included in the efficiency calculation; power supplied to prevent the brake from engaging is not included in this calculation. In lieu of powering the brake separately, the brake may be disengaged mechanically, if such a mechanism exists and if the use of this mechanism does not yield a different efficiency value than separately powering the brake electrically.
3.2. Close-Coupled Pump Electric Motors and Electric Motors with Single or Double Shaft Extensions of Non-Standard Dimensions or Design:
To attach the unit under test to a dynamometer, close-coupled pump electric motors and electric motors with single or double shaft extensions of non-standard dimensions or design must be tested using a special coupling adapter.
3.3. Electric Motors with Non-Standard Endshields or Flanges:
If it is not possible to connect the electric motor to a dynamometer with the non-standard endshield or flange in place, the testing laboratory shall replace the non-standard endshield or flange with an endshield or flange meeting NEMA or IEC specifications. The replacement component should be obtained from the manufacturer or, if the manufacturer chooses, machined by the testing laboratory after consulting with the manufacturer regarding the critical characteristics of the endshield.
3.4. Electric Motors with Non-Standard Bases, Feet or Mounting Configurations:
An electric motor with a non-standard base, feet, or mounting configuration may be mounted on the test equipment using adaptive fixtures for testing as long as the mounting or use of adaptive mounting fixtures does not have an adverse impact on the performance of the electric motor, particularly on the cooling of the motor.
3.5. Electric Motors with a Separately-Powered Blower:
For electric motors furnished with a separately-powered blower, the losses from the blower's motor should not be included in any efficiency calculation. This can be done either by powering the blower's motor by a source separate from the source powering the electric motor under test or by connecting leads such that they only measure the power of the motor under test.
3.6. Immersible Electric Motors:
Immersible electric motors shall be tested with all contact seals removed but be otherwise unmodified.
3.7. Partial Electric Motors:
Partial electric motors shall be disconnected from their mated piece of equipment. After disconnection from the equipment, standard bearings and/or endshields shall be added to the motor, such that it is capable of operation. If an endshield is necessary, an endshield meeting NEMA or IEC specifications should be obtained from the manufacturer or, if the manufacturer chooses, machined by the testing laboratory after consulting with the manufacturer regarding the critical characteristics of the endshield.
3.8. Vertical Electric Motors and Electric Motors with Bearings Incapable of Horizontal Operation:
Vertical electric motors and electric motors with thrust bearings shall be tested in a horizontal or vertical configuration in accordance with the applicable test procedure under section 2 through section 2.4.3 . of this appendix, depending on the testing facility's capabilities and construction of the motor, except if the motor is a vertical solid shaft normal thrust general purpose electric motor (subtype II), in which case it shall be tested in a horizontal configuration in accordance with the applicable test procedure under section 2 through section 2.4.3 . of this appendix. Preference shall be given to testing a motor in its native orientation. If the unit under test cannot be reoriented horizontally due to its bearing construction, the electric motor's bearing(s) shall be removed and replaced with standard bearings. If the unit under test contains oil-lubricated bearings, its bearings shall be removed and replaced with standard bearings. If necessary, the unit under test may be connected to the dynamometer using a coupling of torsional rigidity greater than or equal to that of the motor shaft.
10 C.F.R. 430 app B to Subpart B of Part 431