ECN Forum Forums General Topics of the Trade General Discussion Area How to Measure Power Factor

How do you measure power factor and what do you measure it with. Is there some type of hand held meter that can be used to measure watts as I am told this is really what you are looking for and trying to reduce?

Thanks,
Roger

I assume you're asking about a meter for small appliances that plug into 120 V receptacles. Fortunately, there's a really neat meter for the purpose, and it's less than $25.

Froogle "kill-a-watt" -- you can't miss it.

It's a digital meter that measures RMS voltage and current, frequency, power, power factor, and VA, and it's become an indispensable part of my tool kit.

Hey, John what model do you have, do they vary in options/ performance? Froogle? I thought you were kidding!!

I'm pretty sure there's only one model, the P4400. Here's the manufacturer's web page for it.

They make great gifts for gadget geeks!

Roger,

What exactly are you looking to measure, or is your question in general about PF?

The power factor question is related to a Rotary Phase Converter. I am trying to reduce the converters power consumption to the least possible amount. I just wanted to know how to measure the power draw from the two single phase legs on the input side so that is necessary I can add capacitance between these two legs to get the power factor closer to 0.9. Everything that I have been read is that a Rotary Phase Converter produces a bad power factor.

Roger

First of all...the "Kill-a-watt" is sold in the ECN store!

Power factor, simply put, is the difference between "watts" and "kva."

If you have a steady load, you can get a good idea by comparing the meter reading to whay you get when you measure volts, measure amps, and multiply the result. This is one of those times you want to have "true RMS' type meters!

Roger, count me in on this one. I want to see you get through it, and learn with you if you don't mind.


Give us the motor size and readings, and we can walk you through it, and all learn something together.

Radar??

rhpope, what did you ever do about this concern?

Reno is quite right here.
Power factor is the ratio of useful power(VxI) to useless (Wattless) power in a circuit or even an entire installation.
To a degree, the lower the wattless component, the higher the power factor.
It is about using the most from what you have supplied to you.
We had a dedicated PF meter at the PoCo, but I can't at this moment remember how it was wired.
What's even more scary, is the fact that I built the thing in the first place.