Art Godfrey (retired)
Birclar Electric & Electronics

No-load testing of repaired motors is common in most if not all repair service centers. ANSI/EASA AR100-2010 Recommended Practice specifies, “for AC motors, no-load running tests should be made at rated voltage and rated frequency.” For sine-wave powered motors, this statement is straightforward. For motors used on variable frequency drives (VFDs), there are a number of possibilities service centers may employ with the motor supplied by line (utility) power, and in some cases the tests may be less than ideal.