Starting Power Factor of Air Conditioners
Starting Power Factor of Air Conditioners
(OP)
I work for an electric utility in Oklahoma. Our Design Standards department is trying to tell me that a residential air conditioner has a starting power factor of .35 lag. I find this hard to believe. This results in almost four volts of flicker drop in a 25 kVA transformer. Does anyone know the typical starting power factor for an air conditioner motor? Is the starting power factor for a reciprocating compressor motor different than the pf of a scroll compressor motor? If anyone knows where I can find this type of information I will be glad to go look it up. I searched ARI (American Refrigeration Institue) but had no luck finding anything pertinate. Thanks.





RE: Starting Power Factor of Air Conditioners
RE: Starting Power Factor of Air Conditioners
RE: Starting Power Factor of Air Conditioners
RE: Starting Power Factor of Air Conditioners
Yes, I understand that starting an induction motor results in a low starting power factor. However, I thought that residential air conditioners have a starting capacitor that reduces the amount of current draw on start up and raises the starting power factor to something higher than .35?
Thanks for replying.
RE: Starting Power Factor of Air Conditioners
RE: Starting Power Factor of Air Conditioners
It doesn't matter whether it's a reciprocating compressor or a scroll compressor, you're starting an electric motor and not the compressor.
You didn't say what size unit this was, but try running the calculations for a 5 ton unit, not pretty.
Mark in Utah
RE: Starting Power Factor of Air Conditioners
Concerning your flicker of 4 volts, I have measured 5.5 volts of flicker(120V base) at a customer's service panel, served from a 15kVA transformer with 200' of 4/0AL underground service wire. This is about 4 1/2% flicker. A study done many years ago(1960's ?), found that most people don't find the flicker of incadescent lights objectionable until it exceeds 4.2%, this is at 4 motor starts per hour, which is typical for air conditioners.
RE: Starting Power Factor of Air Conditioners