Lxnxjxhx said:
Doesn't your electric meter read watts and not VAs, if if your PF is not at 0?
Yes, it reads watts (watt hours) not VA. A customer asked me about one of these devices a few months back. Being skeptical and curious I wanted to see how they were claiming to save up to 25%, so I searched online and found a test report for one of these power saving devices that was supposedly done by an independent lab for the maker of the device. I was refreshed to find that the data in the report made sense, even if it wasn't presented very scientifically. The data showed that the power (watts) was unchanged or slightly higher when the device was connected, and that the VA was a little lower in some cases. The written conclusions, however, conveniently ignored the relevant data in the report.
The report said nothing of resistive losses in the house wiring, which is the only thing I could see that could conceivably be a
very small benefit of PF correction for the home owner at the residential level. But this really works against the device because any minor saving in resistive losses in the circuit wiring when an appliance motor was operating would be more than outweighed by the increased resistive losses from the larger current flowing due the over-corrected (negative) PF when the appliance motor was not operating.
Dave
