nuckolls.bob(at)aeroelect Guest
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Posted: Mon Aug 14, 2017 9:19 am Post subject: Alternators - To Fuse or not to fuse - That IS the questi |
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At 12:08 PM 8/12/2017, you wrote:
Quote: | The conundrum lies in your assumptions. You are assuming that if the field circuit breaker pops something must be wrong with the alternator system. Not necessarily the case. I'll leave it to others with more understanding of such things to elaborate. |
B&C regulators are fitted with crowbar ov protection
that deliberately opens the field supply breaker. When
running TWO alternators, it would normally be possible
for ONE alternator to go into ov runaway and trip
both systems . . .
EXCEPT . . .
B&C controller ov systems watch the field voltage
of their respective alternator. If an ov condition
is detected, the field voltage on the failed system
is high . . . the working system's field voltage
is low if not zero. The ov system on the working
alternator is prevented from operating thus leaving
the working system on line.
I think I offered the first selective trip ov protection
system to Cessna waaayyy back when we were asked
to propose a paralleling alternator controller for
the Crusader. Got beat out by ElectroDelta on that
project. I don't recall if their offering included
selective trip . . . it might have been in
Cessna's procurement specification.
Bob . . .
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