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From: Jim Pennino
Subject: Re: (Avionics) How can this circuit produce an "inductive surge"?
Date: Tue, 1 Oct 2002 02:12:48 +0000 (UTC)
Organization: Special Solutions, LLC
References: <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com> <firstname.lastname@example.org> <email@example.com>
NNTP-Posting-Date: Tue, 1 Oct 2002 02:12:48 +0000 (UTC)
User-Agent: tin/1.4.5-20010409 ("One More Nightmare") (UNIX) (SunOS/5.9 (sun4u))
In rec.aviation.owning Tarver Engineering wrote:
> "Jim Pennino" wrote in message
>> In rec.aviation.owning Tarver Engineering wrote:
>> > "Peter Gottlieb" wrote in message
>> > news:CLOl9.16392$CN2.firstname.lastname@example.org...
>> >> "Tarver Engineering" wrote in message
>> >> news:email@example.com...
>> >> > > >
>> >> > > > You do know that floresent ligting is far harder on an UPS than
>> >> > induction
>> >> > > > motor, do you not?
>> >> > > >
>> >> > >
>> >> > > So what? These are all 4 quadrant units. I use fl lighting on a
>> >> for
>> >> > > emergency lighting, much more efficient than incandescent. I
>> > say
>> >> > the
>> >> > > series motor was the *only* test, did I?
>> >> >
>> >> > Well really, we were running big motor generator sets, to make 400
>> > cycles
>> >> > (or 408 HZ IBM), off UPS 20 years ago. Running a motor with an UPS
>> >> > hardly an accomplishment.
>> >> >
>> >> > To make the any load claim you would have to be able to drive all
>> >> floresent
>> >> > lights.
>> >> Why would you run a static inverter to make one frequency of AC then
> use a
>> >> MG set to convert to another frequency?
>> > Isolation.
>> Prey tell me how any electrical noise on the input to the motor can
>> be transmitted across the steel shaft driving the generator or how
>> input variations escape the inertia of the big flywheel on such a setup?
The isolation of a MG set happens by virtue of the mail lines being
connected to the motor. The motor is in turn connected to the generator
by a (usually) steel shaft. Therefor, electrical tranients on the mains
can not appear in the generator output; there is no electrical connection,
only a mechanical one.
Temporary line sags are damped out by the mechanical inertia of the flywheel
in the MG set.
The output of the generator is a nice, clean sine wave of constant value.
>> The metrology lab in a place I worked a few years back had a pair of
>> such beasts, one 60 Hz and one 400 Hz. We used battery powered test
>> equipment to verify the outputs. REALLY clean output.
> The 400 cycle UPS had just begun to replace some motor generators 20 years
And ice cream has no bones.
The reason I was using this stuff was to look at the thermally generated
electrical noise in circuits at around room temperature. Without the clean
power of the MG you couldn't such signals because the perturbations caused
by noise on the mains was thousands of times larger.
The only reason for a MG set is to provide extremely clean power or to
convert from on frequency to another, i.e. 60 Hz to 400 Hz.
>> The only reason I can see for driving with a UPS is if you are running
>> a long, one chance at it, experiment that can not interrupted until
>> it finishes.
> You mean like batch?
You mean this lash up was just to run a computer system?
What people that know what they are doing do is to power the computer
directly by the UPS and have a gas or diesel generator backing up the
mains if things are that critical.
This is called guarding against power failure and has nothing to do with
You do understand that in the civilian world "motor generator set" usually
refers to an electrical motor driving a generator?
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