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>[Epplin John A]
><see original long message>
>
>One question I have: What is the generator capacity? I suspect the T-6
>has at least a 100 amp generator. The ammeter shunt should be capable
>of more than the continuos capacity of the generator. D.C. generators
>are usually capable of at least 200% rated load for a short time.
Not if their regulators are working . . . there are three "relays"
in a generator's regulator: reverse current cutout, voltage regulation,
and current regulation. Failure of the current regulation "relay"
puts generator at risk for much smoking.
> There
>is no current regulator installed with most high capacity DC generators.
>Alternators generally are self limiting in current. They usually will
>not produce much more than there rated output.
Can you tell me of a system that's not current regulated. I'm trying
to recall if there was a current reguation feature in the old carbon
pile regulated systems . . I don't think their was. Modern starter
generators are limited via electronics that watches the drop across
a series compensation widing . . . a sort of quasi ammeter shunt.
>
>I realize this is a problem with instrumentation. You want to be able
>to determine if the gen is working, hard to do if you only have a 10 amp
>load and a 150 amp meter. The answer lies in the voltmeter. In my
>opinion the battery voltage is a better indication of the overall system
>condition than the ammeter. For my money, I would keep the existing
>ammeter and add a voltmeter. The ammeter could be a valuable asset in
>case of some malfunction such as a shorted cell, the amps would be high
>with normal voltage.
Well taken. I used to believe that the battery ammeter (-0+) indicator
was the most useful if one were to install a single instrument. 10 years
later with the evolution of essential busses and rerouting of the alternator
b-lead to the starter contactor, that type of ammeter is difficult to
implement. Besides, you still need a "battery gas gage" for alternator
out operations. Soooooo . . . an alternator load meter AND a voltmeter
are good things to have.
>I do like your idea of calibrating the instrument in percent load and
>installing the appropriate shunt. This is really what you are
>interested in anyway. The pilot should know what % to expect as normal
>for the conditions.
It also reduces the number of ammeters I have to inventory!
Regards,
Bob . . .
AeroElectric Connection
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