Medium Electric Motors
Electric motors convert electrical energy to rotating mechanical energy. When operating, the electrical energy is transferred as useful mechanical energy to some driven device such as a fan, pump, blower, compressor, or conveyor. The energy efficiency standards address that portion of electrical and mechanical energy that is consumed as losses within the motor itself.
Commercial and industrial electric motors losses covered by the standards represent approximately 5 percent of electricity consumed annually in the United States. The energy usage for commercial and industrial electric motors varies by sector, application, motor design, and size.
Energy Efficiency Standard:
On July 23, 2012 The Department of Energy (DOE) published a notice of public meeting and availability of the preliminary technical support document regarding energy conservation standards for certain types of electric motors that are currently unregulated by any standards. Further information on this rulemaking may be found on DOE’s Electric Motors webpage.
The Energy Policy and Conservation Act (EPCA), as amended by the Energy Policy Act of 1992 (EPACT), established energy conservation standards and test procedures for certain commercial and industrial electric motors manufactured (alone or as a component of another piece of equipment) after October 24, 1997.
The Energy Independence and Security Act of 2007 (EISA 2007) updated the energy conservation standards for those electric motors already covered by EPCA and established energy conservation standards for a larger scope of motors not previously covered. These amendments went into effect on December 19, 2010. DOE is required by statute to publish a final rule determining whether to amend the EISA 2007 energy conservation standards for electric motors by December 19, 2012. Normal 0 false false false EN-US ZH-CN X-NONE
The current standards correspond to Table 12-12 of National Electrical Manufacturers Association (NEMA) MG1-2006, “Full-Load Efficiencies for 60 hertz NEMA Premium Efficiency Electric Motors Rated 600 Volts or Less (Random Wound),” for subtype I motors and NEMA Table 12-11 of NEMA MG1-2006, “Full-Load Efficiencies of Energy Efficient Motors,” for subtype II, fire pump, and Design B motors.
The efficiency metric for commercial and industrial electric motors is the energy efficiency, defined as output power divided by input power, expressed as a percentage:
(Output / Input) x 100
There are variations in the motor characteristics even in motors of the same design and manufacturer. These are caused by normal variations in raw materials, testing accuracy deviations, and manufacturing processes. Therefore, to rate a motor’s efficiency in a consistent way, the energy conservation standard for electric motors uses a table of fixed nominal full load energy efficiency ratings, which represent the average efficiency of a population of motors of duplicate design for different horsepower, enclosure, and pole configurations. The actual efficiency of the motor is guaranteed to be within a tolerance band of this nominal efficiency. The current standards establish the maximum variation by allowing motors with up to an additional 20% of motor losses to meet the standards.
There are four main categories of motors:
· general purpose electric motors (subtype I),
· general purpose electric motors (subtype II),
· fire pump motors, and
· NEMA Design B general purpose electric motors (from 200 hp through 500 hp).
Within each category, EISA 2007 set separate standards by horsepower, enclosure, and pole configuration.
In amending these energy conservation standards, DOE is analyzing these design features as product class-setting criteria:
· Horsepower rating
· Pole configuration
· Enclosure type
· NEMA Design letter
· Frame type
· Mounting feet
· Other features (e.g. close coupled pump motors, fire pump motors, and vertical solid shaft normal thrust)
Under contract to DOE, LBNL's Energy Efficiency Standards (EES) group is conducting the following analyses for the 2012 final rule.
- Energy Consumption
- Life-Cycle Cost and Payback Period Analyses
- Shipments Analysis
- National Impact Analysis (National Energy Savings and Net Present Value)
- LCC Consumer Sub-group Analysis
- Utility Impact Analysis
- Employment Impact Analysis
- Environmental Assessment Report
- Regulatory Impact Analysis
Efficiency Standards History:
The amendments created by EISA 2007 comprise the most recent revisions to EPCA and the energy conservation standards for electric motors. DOE is planning to publish a final rule to determine whether to amend the EISA 2007 energy conservation standards for electric motors by December 19, 2012. Any amended standards that DOE establishes would be published as part of that determination and would apply to electric motors manufactured on a date starting no earlier than five years after the December 19, 2010, effective date of the previous electric motors standard. Therefore, any amended standards that DOE establishes as a result of this rulemaking would have a compliance date of December 19, 2015.