In article
,
"Vaughn Simon" wrote:

This conversation started about refrigeration motors which can be quite fussy
about waveform, but it is little understood that modern electronics have
switching power supplies that can be pretty insensitive to waveform.
Strangely,
your computer is more likely to run well off of your cheap inverter than your
refrigerator, even though both of them may require about the same wattage.

(I am trying to remember all this from college physics)
Think about how a refridgeration system "starts" and runs.
There is usually a "start-run" capacitor.
The capacitor is a "voltage" device.
The motor to run the compressor is a "current" device.
ELI ICE
Voltage leads current in an inductor (motor) by 90-degrees
Current leads voltage in a capacitor by 90-degrees

This has to do with the current and voltage phase with respect to each
other. This is really neat to watch on an oscilliscope.
Draw a picture of two sinewaves, shifted by 1/4-wavelength.
As you start up the compressor, the motor draws a slug of current, so
the sinewave current waveform distorts to look something like a sharks
fin. As the current gets sucked into the wires of the inductor, the
voltage collapses. The start-run capacitor dumps its stored voltage to
hold the line voltage up until the current draw diminishes as the
magnetic field is established. Then the capacitor draws a slug of
voltage to recharge itself, and the voltage waveform takes on the
sharkfin shape. And then the process repeats itself.
(Does that sound right to the experts out there?)