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Federal Register / Vol. 86, No. 11 / Tuesday, January 19, 2021 / Rules and Regulations requirements of the NEMA Premium Motor program. Additionally, motor horsepower dictates the maximum load that a motor can drive, which means that a motors rated horsepower can influence and limit the end use applications where that motor can be used. Horsepower is a critical performance attribute of a small electric motor, and since horsepower has a
direct relationship with average full load efficiency and consumer utility, DOE used this element as a criterion for distinguishing among equipment classes in the March 2010 Final Rule. 75 FR
10886. DOE relied on the same approach for the proposed determination. See 85 FR 24146, 24153.
DOE did not receive any comments on the current structure of the equipment
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classes as assessed in the April 2020
NOPD. Accordingly, in this final determination DOE continues to assess the SEM equipment classes as currently established. Table IV2 summarizes the structure of the equipment classes identified for this final determination and as designated by the current standards at 10 CFR 431.446.

TABLE IV2SUMMARY OF SMALL ELECTRIC MOTOR EQUIPMENT CLASSES
Motor topology
Pole configuration
Single-phase:
CSIR
CSCR
Polyphase

See chapter 3 of the final determination TSD for further discussion of the equipment classes.
3. Technology Options for Efficiency Improvement The purpose of the technology assessment is to develop a list of technology options that could improve the efficiency of SEMs. For the motors covered in this determination, energy efficiency losses are grouped into four main categories: I2R losses,9 core losses,
friction and windage losses, and stray load losses. The technology options considered in this section are categorized by these four categories of losses.
The SEMs evaluated in this determination are all AC induction motors. Induction motors have two core components: A stator and a rotor. The components work together to convert electrical energy into rotational mechanical energy. This is done by creating a rotating magnetic field in the
2, 4, 6
2, 4, 6
2, 4, 6

Motor output power hp 0.253
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stator, which induces a current flow in the rotor. This current flow creates an opposing magnetic field in the rotor, which creates rotational forces. Because of the orientation of these fields, the rotor field follows the stator field. The rotor is connected to a shaft that also rotates and provides the mechanical energy output.
Table IV3 summarizes the technology options identified in the April 2020 NOPD.

TABLE IV3SUMMARY OF TECHNOLOGY OPTIONS FOR IMPROVING EFFICIENCY
Type of loss to reduce
Technology option applied
I2R Losses

Core Losses

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Friction and Windage Losses

Use a copper die-cast rotor cage.
Reduce skew on conductor cage.
Increase cross-sectional area of rotor conductor bars.
Increase end ring size.
Changing gauges of copper wire in stator.
Manipulate stator slot size.
Decrease radial air gap.
Change run-capacitor rating.
Improve grades of electrical steel.
Use thinner steel laminations.
Anneal steel laminations.
Add stack height i.e., add electrical steel laminations.
Use high-efficiency lamination materials.
Use plastic bonded iron powder.
Use better bearings and lubricant.
Install a more efficient cooling system.

85 FR 24146, 24155.
DOE did not receive comments on the technology options identified in the April 2020 NOPD. Accordingly, DOE
continued to consider the technology options identified in the April 2020
NOPD in developing this final determination. Chapter 3 of the TSD
provides details on the DOEs market and technology assessment for SEMs.

B. Screening Analysis
9 I2R losses refer to conductor losses. In AC
circuits, these losses are computed as the square of
the current I multiplied by the conductor resistance R.

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DOE uses the following five screening criteria to determine which technology options are suitable 10 for further consideration of new or amended energy conservation standards:
1 Technological feasibility.
Technologies that are not incorporated in commercial products or in working
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prototypes will not be considered further.
2 Practicability to manufacture, install, and service. If it is determined that mass production and reliable installation and servicing of a technology in commercial products could not be achieved on the scale necessary to serve the relevant market at the time of the projected compliance date of the standard, then that 10 DOE refers to the technology options that pass the screening criteria as design options.

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