Fred,
Thanks for your answer.
>
> I have only the one, plus the internal photos, which you shared with me;
nothing independent of that.
>
> > We've been conducting some investigation into the Rotax regulators, and
they
> > appear to be far from cleverly engineered.
>
> [Nerdy tech stuff follows]
>
> By clever I meant it's an SCR shunt regulator, but they don't use a bridge
rectifier, which is not fail-safe because the ground return is hard-wired.
But here each SCR alternately provides its sibling's ground reference during
the period it is letting a half-cycle of AC pass. If one SCR opens or
shorts, output will be seriously reduced. Another failure mode is ground
reference totally severed, so B+ just floats in space, effectively zero
output.
>
Oh, interesting.
> However, your engineer friend may be better at this stuff, with less
chance of being wrong!
>
I'm forwarding our messages to him.
> > Even at 10 A, half the advertised 20 A rating, the unit gets notably
> > hot.
> Is is cooler at around 15A? A shunt regulator can be and if so, a good
excuse for more avionics?
>
We got the impression it was hotter at 12 A than at 10 A. I could barely
touch the case for more than a few seconds.
However it was just a quick and dirty test yesterday before going home to
dress for the New Year's party. More precise measurements will follow.
Tomorrow I'll play with hacksaw and electric drill to strip another failed
unit in order to get a more accurate diagram.
Will keep you posted.
Regards,
Gilles
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