>
> 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
Ahh... there in lies my concern with adding a crow bar protection:
1. False triggering will unload the alternator, possibly damaging the
voltage regulator.
2. Triggering of the device will add to the pilot load, and with a crowbar
device you have no way of determining if you have a legitimate OVP
situation.
3. It adds a bunch more parts to the system.
4. It is not clear to me if the rotax alternator even has enough capacity
to create an OVP situation..
5. The only documented regulator failures I have been able to find so far
are where the output declines.
So, I am at the point where I have all of the components required to add
crowbar protection, but I am unsure if its really a great idea. I am
leaning towards just adding a 30 amp circuit breaker and setting over
voltage alarms on my EIS.
I'd welcome more input on this topic as I remain undecided.
Paul
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