There are so many products out there that sales people misrepresent, the way to know the facts? Test it yourself. ‘Hands on’. Of course it’s nice to know the difference between KVAs and KWHs before you start.
Video of Test Bench in operation
Above: Part of the Utterpower Test Bench.
If you frequent the haunts I do, you will see a lot of claims where power in VS power out are outside what physics and the constraints of living here on earth allow. One of the ways you can keep from fooling yourself is to have good test equipment like a power analyzer with calibration papers and in addition have a secondary measuring device(s) just for good measure. Use only resistive loads since this relieves you of calculating the power factor in order to find true power. An analyzer that calculates power in watts will help you avoid common mistakes like resistance changes in common resistance load boxes as they heat up and stabilize. At present, my test bench can place a 5.5 KW load on the PMG, and since the 3 phase prime mover is powered by a processor controlled variable frequency drive, we can adjust for the exact frequency before we take our readings. The prime mover has a torque arm that can be connected to a strain gauge, we can also measure power into the Motor and compare that to the power out of the generator head to get some idea of efficiency from one Gen head to another. In the picture above we have the 3KW continuous rated PMG under test.
Other loads available to the test bench include a one horsepower submersible deep well pump down a little over 100 feet. Since the 3KW pmg can easily supply 5.5 KW or more at good voltage, we get quick pump starts.