Aww, you sprung my trap!

The previous poster was expostulating on running the motor on 3, 2 and 1
phase. I was waiting for him to show me the difference between the 2 phase
and single phase connections!

Same basic concept as phase rotation in a 3 phase system. You and I think
there are only two, but there are really many; ABC, BAC, CBA, ACB etc.etc.

(Facetious mode turned OFF)

I spent many years in an old manufacturing city in the Northeast, where we
had, in common use on a daily basis, AC (25 and 60 Hz), DC, every possible
permutation of 3 phase, 2 phase 3,4 and 5 wire, and everything in between.
My absolute favorite was the 6 phase double delta. Picture a straight 220
(YES, 220, not 240) delta connection. Now, center tap all the transformers,
and these midpoints give you another delta at 110 for the lighting load. Of
course, the whole thing is ungrounded. Yes, all the light switches in the
building were 2 pole. Yes, the small motors were 110 volt 3 phase. This
system gives you 2 three-phase voltages out of one set of transformers, The
power factor transforms at unity, unlike many connections. Only thing is, it
is very had to protect the transformers unless you use 6 primary fuses.

Years ago, maintenance electricians had to be aware of a lot of varied
systems. Today, life is a whole lot simpler.

Thanks in advance.

"Spehro Pefhany" wrote in message
news
On Sat, 3 Jan 2004 09:30:19 -0500, the renowned "BFoelsch"
wrote:

How would you hook up a 3-phase motor to run on 2 phases?

A 3-phase motor has 3 wires. If you break one wire, it's running on
single phase, not two. Break two wires and it tends to just sit there.

How would you hook up a 3 phase motor to run on one phase?

I don't care whether they work or not, I just want to see the wiring
diagram.

Single phase applied to two of the three wires. It works better with
capacitors to the third (otherwise unconnected) wire. The motor won't
start like this, you either need to give it a spin or use another
(starting) capacitor and some switching.


Best regards,
Spehro Pefhany
--
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