The electric company was working on the power lines for four days out in the woods, so they put our street on huge diesel generators (each was the size of a small car) that ran constantly to supply us with power. Everything worked fine, but I noticed some anomalies:
My roof solar panels were not working.
The clicking "igniter" on the gas range clicked faster than usual.
The microwave, when cooking, made a louder higher noise than usual.
So my question is: what was "wrong" with the power coming through the lines that distinguished it from what comes in normally? How did these appliances "know" something was odd? Was the Hz too fast?