Today's Message Index:
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1. 10:01 AM - Re: Re: Over Voltage Crowbar (Robert L. Nuckolls, III)
2. 10:41 AM - Re: Re: Over Voltage Crowbar (correction) (Robert L. Nuckolls, III)
Message 1
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| Subject: | Re: Over Voltage Crowbar |
>
>I think the existing selection provides a time delay of 10 to 11
>usec, depending on the voltage sensed. Yes, I think you are correct
>that this might be a bit too "twitchy." Using the added cap as you
>suggest is certainly an easy way to modify the behavior without
>component replacement. Something that might be necessary for any
>specific aplication.
Legacy qualification for 14v avionics cites
a requirement to stand off a 20v surge for
1 Second; 40v surge for 100 mS.
Waaayyyy back when, we adjusted ov trip time
constants to respond to a 14.2 to 20V step
input in 50 plus or minus a few milliseconds.
While 'useful' it was far faster than necessary
and occasionally caused problems with nuisance
tripping.
If I were updating the OVM14, it would be
processor based with a software timer that
trips for any voltage event exceeding
15 volts by more than 500 mS. If the input
drops below 16v before time-out, the timer
resets and starts over.
In any case, your trip response time target is
defined in HUNDREDS of milliseconds.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Message 2
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| Subject: | Re: Over Voltage Crowbar (correction) |
If I were updating the OVM14, it would be
processor based with a software timer that
trips for any voltage event exceeding
15 volts by more than 500 mS. If the input
drops below 15v before time-out, the timer
resets and starts over.
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
Bob . . .
Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"
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