3 phase power measurement

Not open for further replies.


I would like some advice on how to measure Real Power in a 3 phase power distribution system. I believe that the best way to do this is to use the 3 wattmeter method but these meters are quite expensive. Can I buy a single phase wattmeter and measure each leg separately? Then add the phases together? Fluke makes a meter that does this calculation internally but it must be a balanced load. My situation would be unbalanced (a mixture of 3 phase motors and single phase devices)

Thanks for any advice.



Re: 3 phase power measurement

Hello Dan-

You are correct about using the single-phase meter, then adding the phases to get the measurement you want.

Fluke does have some nice equipment, but I would stay away from their 43 Power Quality Analyzer. They should have done more market research to make this a better tool for PQ analysis.

The Fluke 41B Power Harmonics Analyzer will do what you need and then some for about $2000.

If you can spend some time searching the surplus stores online, or Ebay, you could get away with using the Fluke 39 Power Meter. It is discontinued, but when new cost $1000.

The only difference between the 39 and 41B is the ability to download the data into a computer- hardly worth the $1K. (Yes, the 39 will also measure harmonics.)

I'm just curious- is your facility suffering some sort of PQ problem(s) that warrants this measurement, or did you need this information for general electrical maintenance reasons?



charlie tuna

Senior Member
Re: 3 phase power measurement

how accurate must this information be? if the load is imbalanced, the readings on one phase will not mean much when looking for total load. especially if you have changing load conditions.

charlie b

Staff member
Seattle, WA
Electrical Engineer
Re: 3 phase power measurement

I am closing this topic. It is a duplicate. Please continue any discussions in the Engineering area.
Not open for further replies.