Notes that electric adjustable speed drives (ASDs) are increasingly used in HVAC equipment because of the energy savings and ease of operation they offer. Describes field and laboratory tests of three modern power meters and analysers by subjecting them to waveforms produced by the three commonest ASD technologies used in air conditioners and heat pumps - PWM induction, DC- brushless and switched-reluctance drives. The results show that some meters can accurately measure electric power at the input to ASDs. However the power output of ASDs for DC-brushless and switched-reluctance technology was not measured with acceptable accuracy by any of the tested meters. Gives possible reasons for these inaccuracies and suggestions for performance improvement.

KEYWORDS: year 1997, Electrical installations, performance, testing, laboratory testing, meters