Auxilary Alternator Question...

I am studying Z-13/8 and was wondering about the Auxiliary Alternator. Are you supposed to fly with it shut off or turned on? and if it is only supposed to be turned on during a primary alternator failure than what would happen if it is turned on during normal operations? In essence, both alternators would be feeding the same busses from different directions, is that a problem?

I feed two busses from two alternators, and fly with the SD8 switched on.

Works for me.

The regulator on most backup alternators is set to a slightly lower voltage than that of the primary alternator. With both alternators on the backup won't produce anything unless the buss voltage drops due to overload or failure of the primary.

SD-8

My SD-8 is always on when the engine is running. Just use the switch to test things. I called B&C to discuss and they said this was fine and proper.

I will soon be installing the Plane-Power FS1-14B (30 amp, 14.2 volt - not the FS1-14 13.6 volt) as the second alternator switchable through a toggle switch.

The plan at this stage is there will be two wires from the bus, each with a 5 amp circuit breaker to a 2PDT switch (ON OFF ON). The other side of the switch will connect to the field of each alternator. This will allow me to select either the Main alternator or the Aux alternator or both off. With this arrangement only one alternator can be on (field on) at a time.

Fin
9A