From: Richard VanHouten
Subject: Re: (Avionics) How can this circuit produce an "inductive surge"?
Date: Wed, 02 Oct 2002 22:59:40 -0400
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Peter Gottlieb wrote:
> "Richard VanHouten" wrote in message
> > >
> > > Why would you run a static inverter to make one frequency of AC then use
> > > MG set to convert to another frequency? Seems like a real kludge to
> > > not to mention, a very noisy setup.
> > >
> > Well, if this is the product that my employer (then K/W Controls, Inc.,
> > now Piller, Inc.) marketed, the static inverter was a standby unit, and
> > the MG set ran off of mains except during a power failure. The 2 second
> > ride-through of the MG set was plenty of time for the inverter to kick
> > in, and your battery string would give you several minutes to shut down
> > your computers, or let your diesel generator kick in if you had a
> > premium setup.
> > The frequency would drop a bit during the transfer, but IBM's spec said
> > that was ok, as long as it stayed above (I think) 370 Hz.
> Well, that makes some sense. But running a frequency converting MG set from
> a UPS is not an optimal solution - why not just make the UPS run at the
> target frequency? The magnetics at 400 Hz are much lighter and inexpensive
> than those required for 60 Hz, and the higher frequency makes other designs
> practical (eg, resonant).
The original product was the MG set (an import from Anton Piller Gmbh in
Germany), the front end inverter was our own design. IBM was
recommending the Piller MG sets for powering their then-current design
mainframes, so designing a stand-alone 400 Hz UPS would probably have
hurt business. The front-end inverter was a stand-by UPS; the MG set
ran directly off of mains during normal operation. Also, the inverter
had no magnetics to speak of; the MG set provided the power