Chapter 18: Variable Frequency Drive Evaluation Protocol
An adjustable-speed drive (ASD) includes all devices that vary the speed of a rotating load, including those that vary the motor speed and linkage devices that allow constant motor speed while varying the load speed. The Variable Frequency Drive Evaluation Protocol presented here addresses evaluation issues for variable-frequency drives (VFDs) installed on commercial and industrial motor-driven centrifugal fans and pumps for which torque varies with speed. Constant torque load applications, such as those for positive displacement pumps, are not covered by this protocol. Other ASD devices, such as magnetic drive, eddy current drives, variable belt sheave drives, or direct current motor variable voltage drives, are also not addressed. The VFD is by far the most common type of ASD hardware. With VFD speed control on a centrifugal fan or pump motor, energy use follows the affinity laws, which state that the motor electricity demand is a cubic relationship to speed under ideal conditions. Therefore, if the motor runs at 75% speed, the motor demand will ideally be reduced to 42% of full load power; however, with other losses it is about 49% of full load power.
- Publication Date:
- OSTI Identifier:
- Report Number(s):
- DOE Contract Number:
- Resource Type:
- Technical Report
- Resource Relation:
- Related Information: Uniform Methods Project: Methods for Determining Energy Efficiency Savings for Specific Measures; Period of Performance: September 2011-December 2014; Work performed by SBW Consulting, Inc. Bellevue, Washington
- Research Org:
- National Renewable Energy Laboratory (NREL), Golden, CO.
- Sponsoring Org:
- USDOE Office of Electricity Delivery and Energy Reliability
- Country of Publication:
- United States
- 24 POWER TRANSMISSION AND DISTRIBUTION; 32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION ASD; ADJUSTABLE SPEED DRIVE; VFD; VARIABLE-FREQUENCY DRIVE; MOTOR DRIVES EVALUATION PROTOCOL
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