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Federal Register / Vol. 86, No. 1 / Monday, January 4, 2021 / Rules and Regulations
C. Rated Output Power and Breakdown Torque of Small Electric Motors The current regulations for small electric motors specify that the metric for energy conservation standards, average full-load efficiency, is to be measured at full rated load. 10 CFR
431.442. The industry testing standards referenced in the small electric motor test procedure do not provide a method to determine the rated load of the tested unit but instead rely on manufacturerspecified output power, which is typically listed on a motors nameplate, to determine average full-load efficiency at full rated load.21 The industry standards do not define rated output power; rather, the output power is a manufacturer declaration.
As explained in the April 2019 NOPR, the motors subject to the small electric motors test procedures are capable of operating over a continuous range of loads. 84 FR 17004, 17014. For example, a motor that is rated at 1 hp is also capable of delivering 0.75 hp, but likely with a different speed, torque, and efficiency than those of when it is delivering its rated load of 1 hp. The output power of the motor depends on the load and the design of the motor.
Therefore, the load point at which the motor must be tested is not an intrinsic parameter of the motor, but rather a parameter that must be defined or specified. The tests load point is relevant to efficiency testing because the efficiency of small electric motors varies according to load.
In the April 2019 NOPR, DOE
proposed to define rated output power using breakdown torque as specified in NEMA MG 12016. 84 FR 17004,
1701417016. In concept, breakdown torque describes the maximum torque the motor can develop without slowing down and stalling. The maximum torque over the entire speed range could occur at a different condition e.g., the motor start-up, zero speed condition than the breakdown condition. As explained in the April 2019 NOPR, breakdown torque corresponds to a local maximum torque on a plot of torque versus speed that is nearest to the rated torque. 84 FR 17004, 17014. The phrase abrupt drop in speed corresponds to the expectation that the motor will slow down or stall if the load increases and indicates that minor reductions in speed observed due to measurement sensitivities are not considered.
The breakdown torque for a specific horsepower rating is specified as a range as a function of input frequency and synchronous speed of the motor in two tables: Table 105 of NEMA MG 12016, which applies to induction motors, except permanent-split capacitor PSC and shaded-pole motors; and Table 106 of NEMA MG 12016, which applies to shaded-pole and PSC motors for fan and pump applications. For polyphase motors, section 12.37 of NEMA MG 12016 specifies that the breakdown torque of a general-purpose polyphase squirrel-cage small motor shall not be less than 140 percent of the breakdown torque of a single-phase general purpose motor of the same horsepower and speed rating.
In the April 2019 NOPR, DOE initially determined that NEMA MG 12016s Table 105 can apply to all small electric motors subject to DOEs standards and that most manufacturers already use the breakdown torque method as a standard practice to determine rated output power. 84 FR
17004, 17016. Accordingly, DOE
proposed to define rated output power as the mechanical output power that corresponds to the small electric motors breakdown torque as specified in NEMA MG 12016 Table 105 for single-phase motors or 140
percent of the breakdown torque values specified in NEMA MG 12016 Table 105 for polyphase motors. 22 Id. DOE
also proposed defining breakdown torque as the maximum torque that the motor will develop with rated voltage and frequency applied without an abrupt drop in speed, determined in accordance with NEMA MG 12016.
Id. DOE requested comment on the proposed definitions for rated output
21 See e.g., CSA C74709, Section 3, Definition of full load; CSA C39010, Section 3.1, Definition of rating; IEEE 1122017, Section 3.3.2
Specified temperature; and IEEE 1142010, Section 8.2 Determination of efficiency.

22 For purposes of this definition, NEMA MG 1
2016 Table 105 can be applied to all small electric motors, regardless of whether elements of NEMA
MG 12016 Table 105 are identified as for small or medium motors.

certification programs, paragraphs b4 and c4.
For electric motors, IEC 6003421 is referenced in 10 CFR 431.12
Definitions the definition for accreditation; and 10 CFR 431.15
Materials incorporated by reference, paragraph c3. The specific references to IEC 6003421:2014 Method 211B
are in 10 CFR 431.19 Department of Energy recognition of accreditation bodies, paragraphs b4 and c4; 10
CFR 431.20 Department of Energy recognition of nationally recognized certification programs, paragraphs b4 and c4; and Appendix B to Subpart B of Part 431 Uniform test method for measuring nominal full load efficiency of electric motors, Sections 22 and 3.

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power and breakdown torque.
Additionally, DOE requested comment on how to determine when an abrupt drop in speed e.g., the local maximum of the torque-speed plot closest to the rated torque has occurred when testing the breakdown torque of a small electric motor. Id.
In response to the April 2019 NOPR, NEMA commented that there is no need to define breakdown torque or abrupt drop in speed for the purposes of testing electric motors. NEMA, No.
84 at p. 3 Specifically, NEMA stated that incorporating breakdown torque as the method to define the rated output power of the motor is unnecessary because NEMA MG 12016, Part 1.40
already states the output rating of a machine shall consist of the output power. Instead, NEMA recommended that the declared values of output power be used as provided on the manufacturers nameplate and that DOE
not require a declaration of breakdown torque. NEMA, No. 84 at pp. 34.
NEMA further stated that the abrupt drop in speed corresponds to the expectations that the motor will slow down or stall if the torque applied to the motor exceeds the local maximum value of torque that is most closely located to the rated torque of the motor i.e., the breakdown torque. Finally, NEMA
claimed that performing any additional speed-torque tests for determining abrupt drop in speed would increase manufacturer burden. NEMA, No. 84 at pp. 35 No other comments were received in regard to this issue.
In the April 2019 NOPR, DOE did not intend to suggest that it would require manufacturers to test or report the value of breakdown torque used to establish the rated output power of a small electric motor. Rather, the intent of defining breakdown torque, through reference to the industry standard NEMA MG 12016, was to in turn define rated output power for the purpose of measuring average full-load efficiency. As noted previously, NEMA
responded to the April 2019 NOPR by explaining that NEMA MG 12016 Part 1.40 already states the output rating of a machine shall consist of the output power. NEMA, No. 84 at p. 34 As indicated by its inclusion in NEMA MG
12016, the breakdown torque method is commonly used by industry for determining rated output power.
Defining rated output power based on NEMA MG 12016 provides additional detail that allows for the accurate comparison of small electric motors.
Therefore, in this final rule, DOE
defines rated output power as, the mechanical output power that corresponds to the small electric motors
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