"SRF" wrote in message
...
I'm setting up a hobby machine shop and am getting into the issue of 3
phase
motors. Most of the motors are going to be in the 1 to 3 horsepower
range.
For motors of this size, why would I want to have make three phase power
to
run these machines instead of just swapping out the motors for single
phase?

Thanks.
Steve.

There are a number of answers.
As others have said, industrial 3 phase motors are much better made than the
cheap single phase equivalents.
Used 3 phase machinery is generally cheaper than single phase stuff.
You only need to make one converter instead of buying a number of separate
motors so the total cost is less.
A number of machines use non standard motors so replacing them is difficult.
The answer quoting 120 times per second that the power is zero made me think
a bit. The first reaction was to realise that you are on 60 Hz mains and we
(UK) are on 50 Hz. The other thought was that a single phase motor doesn't
actually rely on single phase as such but it makes another phase by use of
an inbuilt capacitor. This second phase is frequently of a lower power than
the primary phase though hence 3 phase is generally a better motor.

John