Description

Adjustable speed drives that are increasingly used in air conditioners and heat pumps severely draw a nonsinusoidal current from the power grid and produce highly distorted voltage and current waveforms at their output. Three modern power meters and analyzers were tested to determine their accuracy when subjected to waveforms that are produced by the three most common ASD technologies used in HVAC equipment, namely, PWM induction, dc-brushless, and switched-reluctance drives. The tests were performed under field conditions and in a computer-controlled laboratory environment. The obtained results show that some meters are able to measure accurately electric power at the input to ASD’s. However, the output power of ASD’s for dc-brushless and switched-reluctance technology was not measured with acceptable accuracy by any of the tested meters. Possible reasons of meters inaccuracies and suggestions for performance improvement are given. The energy efficiency of a squirrel-cage induction, a brushless dc, and a switched-reluctance motor-ASD sets was tested and analyzed at different loading/speed combinations. Procedures for such energy-efficiency tests were developed that may enhance ASHRAE standards. A survey of currently available on the market transducers for low-cost high-voltage and high-current application was conducted. Laboratory tests on the accuracy of voltage and currents probes were performed. Research conclusion and suggestions for a future work are given.

Product Details

Published:

1997

Number of Pages:

171

File Size:

1 file , 2.9 MB

Product Code(s):

D-RP-770