On 25 Aug 2004 19:18:36 GMT, (Charles A.
Sherwood) vaguely proposed a theory
.......and in reply I say!:

remove ns from my header address to reply via email

Thanks for all the replies. I am interested because I see 3PH stuff
for peanuts, and single phase stuff is often limited in power.

conversion to RPCs than it is to find alternators. Alternators should be
driven at a constant speed, regardless of load - not an easy thing.

Not all the hard. There are governors on industrial engines that do
it well. Even the consumer quality generators do a pretty decent job
of it.

Alternators need a separate source of direct current for magnetic
excitation - also adding to the complexity.

Modern brushless alternators have the excitor built in and will
be self starting and self exciting. Some require an external
regulator which uses a tiny amount of generated AC to power the field.
For example the field on my 15KW unit is 30VDC at 1 amp. This
tiny control voltage is produced by the bassler regulator which
is powered by the alternator itself.

These were my thoughts, too. Alternators are available, and many have
themselves set up to generate power as bought. There certainly are
engines with governors that maintin a very good constant speed.

However, I have supply, but not 3PH. I was looking at using an
electric motor to drive the alternator to get 3PH.

The reason I see the alternator as better is that RPCs and VFDs seem
to have a rep for having trouble with load balance etc. The idea and
construction is simple, but they seem to be "picky". I have never used
one, but read a lot of stuff here about the problems getting them to
behave under various load conditions.

They also do not seem all that efficient, and seem to need a far
larger motor to act as the supply than the load.
************************************************** ***
I have decided that I should not be offended by
anybody's behaviour but my own......the theory's
good, anyway.