"philkryder" wrote in message
oups.com...
Steve - How many equal "steps" are necessary for the MSW inverter to be
a sufficiently close approximation to a "rotary" sine wave?


Careful. Even true 'rotary' generators don't always put out a true sine
wave.

Even the very, very large commercial generators used in power plants, don't
put out a 'pure' sine wave. The number of stator slots and rotor geometry
cause a small amount of harmonics. The exact connections of windings is
often used to help improve the fundamental and minimize some of the higher
harmonics (6th, 9th and 11th are some of the more troubling ones).

After it passes through several transformers, getting to the substation,
most of the harmonics have been filtered out by the characteristics of the
transformers.

So the question, as usual, boils down to 'how good, is good enough?'

daestrom