Abstract
Electric adjustable-speed drives (ASDs) are increasingly used in heating, ventilating, and air-conditioning (HVAC) equipment due to the energy savings and comfort of operation they offer. Power electronic circuits that are employed in ASDs shape their input and output voltage and current waveforms, making them highly distorted from typical power-grid sinusoids. Accurate measurements of voltage, current, and power under nonsinusoidal conditions are essential for determining the efficiency of an HVAC unit and performing separation of losses between an ASD and an electric motor. That information is invaluable for HVAC equipment designers, manufacturers, and users. Three modern power meters and analyzers were tested to determine their accuracy with various nonsinusoidal waveforms applied. The meters were subjected to waveforms that are produced by the three most common ASD technologies used in air conditioners and heat pumps, namely, PWM induction, DC-brushless, and switched-reluctance drives. The tests were performed under field conditions and in a computer-controlled laboratory environment. The results obtained show that some meters can accurately measure electric power at the input to ASDs. However, the output power of ASDs for DC-brushless and switched-reluctance technology was not measured with acceptable accuracy by any of the tested meters. Possible reasons for meter inaccuracies and suggestions for performance improvement are given.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 235-240 |
| Number of pages | 6 |
| Journal | ASHRAE Transactions |
| Volume | 103 |
| Issue number | 1 |
| State | Published - 1997 |
| Event | Proceedings of the 1997 ASHRAE Winter Meeting - Philadelphia, PA, USA Duration: Jan 26 1997 → Jan 29 1997 |
ASJC Scopus subject areas
- Building and Construction
- Mechanical Engineering