Dear Fred,
Do i take it you have something against fuseble links?
IMHO 1: A fusable link is a wiring protection device. It keeps the fire in
a place where you can affort it. It is not a device protecting item. 2:
There is no such thing as response time, it will melt if the current is
higher than the spec. That is well before the wiring behind it starts
smoking.
3: To destruct test such devices without very controlled circumstances
and
equipment is as clever as testing the airbags in your car. Yes, it will
explode. So will fuses, circuitbreakers, switches, anything if you feed
sufficient current through them. 4: Fusable links are used in cars,
today
more than ever. There is no better solution to protect against wireloom
fires.
No, fusable links do not replace circuits breakers, but can do a very good
job in fire protection, especially in case of a crash. If i remember
correctly i think the thread started by somebody asking why or if he still
would need a circuit breaker while mounting a crowbar device. Yes, he will.
A circuit breaker very close to the crowbar. And a fusable link on the
battery side of the feed, if the feed is of any length would be a very good
idea, crowbar or not.
Remains my hobby horse. Are you shure you need a crowbar to add security?
Adding components is adding risk of failure. Even without direct failure,
crowbars can trip due to distant lightning, switching components of or on,
or other glitches. A false alarm with possible disastrous results. In a
worst case scenario with a running wild generator, an overvoltage warning
and a manual generator switch could do the same, but in your control and
reversible.
Overvoltage sensitive devices in our airplane have (or should have!)their
own protection.
Jos Okhuijsen
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