Progressive Industries EMS and Powerline frequency error

Very unusual for 2 reasons?

1) Power line frequencies have to maintained very close to 60 Hz so that power companies can buy and sell power to each other. A very small fraction of 1 Hz.

2) any instrument that measures frequency likely has a crystal controlled built in oscillator. These are also very accurate. They might shift a small amount over a wide temperature range.


Believe it or not, most electrical loads (like an A/C) can tolerate +/- 5-10% shift in frequency. They won't be as efficient and might run hot.