Fred wrote:
"Kevin" wrote in message
...
Fred wrote:
"The Natural Philosopher" wrote in message
...
Fred wrote:
"The Natural Philosopher" wrote in message
...
Fred wrote:
To get the advantages of 3 phase, each waveform has to be close to
sinusoidal.


No it doesn't.

3 phase as far as a motor is concerned, simply means it knows which
way to go round.
What on earth are you talking about? Are you seriously suggesting that
it doesn't matter what the waveform is for each of the phases, that you
can still tell me which way the motor will turn? Wow.


As long as they are 120 degrees apart, it doesn;t matter whether they
are sine, square or spikes. It will go round

If we're measuring degrees then it implies a sinusoid, though in practise
there would be harmonics of the fundamental.

If we apply an arbitrary waveform to each phase of a 3 phase motor, I can
assure you will not be able to tell which way it will turn.


you could if they followed each other like a normal 3 phase wave form
take 3 pulses as below (if it works)

_[]____[]_____
___[]____[]___
_____[]____[]__


I agree, the fundamental for each phase is a sinewave with odd and even
harmonics added to each to make the pulse like the waveforms you sketch.
They aren't arbitrary waveforms.


NO, the fundamental for each phase is a square wave.

Stop weaselling.

The point at which you have to introduce an infinite Fourier series of
sinusoids is the point it ceases to be worth talking about them.