[Milsurplus] Mil generator

[Joe Foley]

You would have to open that can of worms!

What probably happened there was that they HAD 120/240
single phase at one time and needed more power,.. SO,
they pulled another conductor to the pole outside and
invented 3-phase where it wasn't before.

There could also have been an "open delta" service,
which was just a cheaper version of the same thing.

Wild leg, Hot leg, High leg are terms used to describe
the system.  Best to get rid of it,....... IF you can
get the utility to understand that it can be done that
way.  You dont' want to hear that story!

120/208 is the oddball in SOME parts of the country. 
Yes, it is!  Because it's the more modern system. 
Some of the infrastructure in the North East is from
the 1920's and is still in use. Eastman Kodak and
Bausch and Lomb are great museums of industrial
evolution, it's all being used,... still.

The bad side, your electrician may not know what he's
looking at.  The local natural gas company had a
problem where everything ran fine on commercial power,
but when they switched to the back-up genset two new
120 volt control circuits dropped out,... their UNION
electicians were stumped, had NO idea what the problem
was.  The service was just what you've described, Bob.
 Someone who had put in TWO new panels hooked the
neutral bars to the nearest grounding point, this was
on a DELTA system,.... there should have been NO
neutral connection, but they saw a neutral bar and
thought it should have been connected to something.

The new genset was DELTA ONLY.  The commercial service
provided a "neutral" through the ground connection,
not sure how, but there was no  neutral through the
genset so the 120 volt circuits died, actually they
had 240 acrossed the two loads.

um,.... they didn't believe me either, as far as I
know they didn't fix it either.

Joe





--- WA5CAB at cs.com wrote:

> Actually, as Young Bill is always hanging me with,
> don't never say never.  
> Years ago Houston Lighting and Power (more commonly
> known as Houston Looting and 
> Pillage) had a bastard hookup installed in one of
> our pipe coating plants 
> that produced 120/240 single phase and 240 3 phase
> delta.  It consisted of a 
> delta connected 240 volt transformer bank.  The
> center-tap of one (only) of the 
> secondaries was grounded and used as the neutral for
> the single phase loads.  
> Don't ask me why they did it that way unless they
> had a 240 volt delta load but 
> had bought a bunch of 120 volt relays surplus.  The
> part of our coating plant 
> where the transformer bank was located was torn out
> shortly before I became 
> involved, and Irebuilt it and had the bank
> reconfigured as standard 120/208 wye. 
>  But I admit that it was a very unusual hookup and
> that the single phase 
> loads are limited to no more than 1/3 of the total
> bank power.  240 volt circuits 
> usually imply single phase.
> 
> Two phase (90 degree phase angle) was used at one
> time in servo systems.  But 
> not to my knowledge in power distribution systems or
> portable generators.
> 
> In a message dated 3/11/2006 8:14:09 PM Central
> Standard Time, jfor at quik.com 
> writes: 
> > Kenneth G. Gordon wrote:
> > 
> > >[snip] In any case, there is really no way you
> can get 120 VAC on any one
> > >phase, and then have a full 240 VAC between any
> two phases.
> > >Because of the phase differences, the total
> voltage is always 208 VAC
> > >in that case, but you already HAVE that as one of
> the outputs: the first
> > >one you listed.[snip]
> > 
> > You can get a flat two phase, 120-0-120 (in fact
> two of them, 90 degrees 
> > shifted) by using
> > a Scott connected trnsformer. I don't know how
> much they cost.
> > 
> 
> Robert Downs - Houston
> <http://www.wa5cab.com> (Web Store)
> MVPA 9480
> <wa5cab at cs.com> (Primary email)
> <wa5cab at houston.rr.com> (Backup email)
>
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