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Greetings,
I am in the process of building, and appreciate your message. Thanks, I will
wire them together before the breaker.
david
"ELIPPSE" <elippse@sbcglobal.net> wrote in message
news:1150299707.752226.230600@y43g2000cwc.googlegroups.com...
> To those of you who have a circuit breaker between your alternator's
> output and your main buss, here's a wonderful way to fry your present
> old avionics so you can replace them with new ones. This is a real help
> in justifying new avionics to your significant other! If your
> alternator field-circuit-breaker is connected to your main buss, then
> if your alternator breaker opens, either through an overload or
> manually, your main buss voltage will drop. The regulator, sensing
> this, will increase the alternator's field current. 'Course, there is
> no load on the alternator, so its voltage will rise. Eventually, in a
> few milliseconds, the regulator will be pumping maximum current through
> the field. Since we drive our alternators at 7000-9000 rpm, the
> alternator will put out well in excess of 100 volts. Closing through
> the alternator breaker will put this high voltage on your buss. Your
> over-voltage protector, if present, will shut off the field supply, but
> by the time the field collapses, the damage will have been done. Here's
> two things you can do to prevent this and keep your old avionics. Any
> time your alternator breaker opens, pull your field breaker before
> restoring the alternator's breaker. If you do not want to depend on your
> memory in a time of stress, rewire your field circuit breaker to the
> alternator side of the alternator breaker. That way the alternator's
> field will serve as the alternator load and the regulator will be
> sensing the alternator output, thus keeping it in regulation. If you
> do not think this scenario could actually take place, I challenge you to
> do this test on your plane at cruise rpm with lots of avionics load and
> prove me wrong!
>
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Re: Frying your avionics
