Lancair IVP.  TSIO550E.  Standard 65amp primary alternator.  Buss A.


Alternator with Hydralic Pump Problem:

Sometimes when my hydralic pump (gear, flaps) is running for more than a brief period (ex, when flaps/gear are coming up on a go around), my 7.5amp circuit breaker "FIELD" for the main alternator pops.  Of course, the alternator output then ceases.

An added observation: In addition to the HYDRALIC ON lamp illuminating during pump action, the alternator's WARNING LIGHT always flashes during (and only during) hydralic pump running (regardless of whether the CB will pop).

Of course, with hydralic pump on, it uses some 40 amps (as seen on the JPI ammeter).  If this is sustained any more than briefly, the Field CB pops.  The 50 amp Hydralic CB does not pop (annd is perfectly happy).

QUESTIONS:

FIrst...is 7.5 amp field CB correct?  I thought it was, but maybe not?

Second, warning light should come on when battery voltage > alternator output.  Does this mean the Voltage Regulator for the alternator is failing me when the hydralic pump demands exceed capacity of voltage regulator to do its job?  Should I replace the voltage regulator?

Third...or does this mean that I have some sort of current misdirect, when output demands (ie,hydralic pump) exceed supply (alternator output), such the current must come from the battery to make up the difference, and it does it through the FIELD circuit (inappropriately), exceeding 7.5 amp CB tolerance?  Of course, the battery is directly hooked up to the BUSS, and the hydralic pump can be run without engine or alternator tuning, directly from the BUSS. A short somewhere?

Who among us understands alternators and can tell me where to look (more than what I've done)?

Jeff L