Pete sez:

"You think this is simpler than an RPC? I built an RPC from plans on the
'net a few weeks ago, and it was a *lot* simpler than I thought. I wouldn't
want to bother with a generator setup unless I really had no other choice."

Right on, Pete! Also, it is a lot easier to find surplus 3-phase motors for
conversion to RPCs than it is to find alternators. Alternators should be
driven at a constant speed, regardless of load - not an easy thing.
Alternators need a separate source of direct current for magnetic
excitation - also adding to the complexity. Granted, alternators can be
"permanent magnet", eliminating the need for excitation power, but those
types, AFAIK, are not readily available or cost efficient in smaller sizes.
The only example I can think of might be a welding/AC supply "generator"
that outputs 3-phase 220v AC. Again, not nearly as economical as a RPC.
IMO, the only justification for an alternator would be if there was no
commercial power available.

Bob Swinney

"Pete Bergstrom" wrote in message
. ..

"Old Nick" wrote in message
...
Why is a rotary phase convert better than a 3-phase alternator driven
by a high-current single phase motor?

First reason is complexity. Second is efficiency, I'd imagine, though I'm
not an expert.

RPCs seem complex and prone to all sorts of vagaries (with SPC even
more so). Why not obtain high current 1 PH power, or several sources
of 1 PH power, and run a motor that runs a 3-phase alternator?


Pete