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I have one of those "inverter" type microwave oven made by Panasonic. It uses an inverter instead of the traditional iron core transformer to power the magnetron.
I just noticed that this thing draws a lot more power & current than it should. The manual specifies "120V AC 12.7A, 1460W" and 1,300W cooking power.
Measurement with either true RMS or regular ammeter shows actual current draw is around 16A. Based on the specifications given, the power factor comes to around 0.956. Given that, it probably has a harmonics correction so the reading from even an ordinary ammeter should be reasonably accurate.
One possibility is that the interference from the inverter is causing the meter to read abnormally high but given rather unrealistic specifications, I believe my result is reasonable.
It is rather unrealistic that the calculated system efficinecy is
89%(1300W output over 1460W input). 89% efficinecy is unrealistically high when you factor in the loss in drive circuit and magnetron. More realistic answer is: A.) the unit is drawing more than the rated power. B.)the unit is putting out less than the rating C.) combination of both.Assuming my measurement is correct, what's the permissibility of something with NEMA-15P plug drawing in excess of 15A for more than a split second?
If you have an inveter microwave oven, I'd like to know how your unit's current draw compares to the official specification.