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From: "Tarver Engineering"
Subject: Re: (Avionics) How can this circuit produce an "inductive surge"?
Date: Thu, 26 Sep 2002 14:24:21 -0700
X-Newsreader: Microsoft Outlook Express 6.00.2600.0000
"Peter" wrote in message
> Jim Weir wrote:
> >That also is true. On engine startup, that magnetic field collapses in a
> >way when the starter motor is de-energized after the engine starts.
> When the starter motor is de-entergised, it is also at the same time
> disconnected. How can the de-energisation of the starter motor produce
> a spike on the avionics supply? Especially as the battery is still
> connected into the circuit.
Of course a thoughtfull design can eliminate the extent of such dPhi/dT.
> >shutdown, the master switch relay dumps a hell of a spike onto a system
> >just had the massive spike absorber called a battery removed from the
> The master relay coil (which AIUI, and certainly in my case, is used
> to connect the battery to the rest of the aircraft) is powered from
> the *battery* side of the master relay, so de-energising the master
> relay would dump the energy into the battery, not into the circuit
> that has just been disconnected.
Think about what Weir is telling you from a Maxwellian reference frame.
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