Re: Alt Field Circuit Breaker Popping

Rick Hole

That’s not quite correct. The 50a breaker connects the output of the alternator to the bus always unless it is tripped or pulled. Even with engine not running and regardless of the field/regulator being powered. Without voltage at the alternator field the alternator will not produce any current. The bus voltage at alternator output will not result in the alternator drawing any current from the bus because the internal diodes in the alternator block current from going “into” the alternator output. 
A failed alternator with shorted diode(s) (there are typically 6) will cause the 50 amp breaker to trip as soon as the master switch is on. 
The 50mp amp breaker is there for 2 reasons. One, to protect the alternator from producing too much power. Two, to protect the battery should the alternator diode(s) fail. 

Sonia and Rick Hole
Email: r.hole@...

On Jul 31, 2019, at 1:52 AM, Corbin Geiser c_geiser@... [Q-LIST] <Q-LIST@...> wrote:


You are correct.  However, it only activates once the alternator has power and is running.  And since the 5 amp is popping right away then the alternator never gets the chance to excite the stator.  So I’m not sure if it would pop or not as I can’t get that far.


On Jul 30, 2019, at 5:54 PM, logistics_engineering@... [Q-LIST] <Q-LIST@...> wrote:


Your plane only has one large 50 amp breaker on the panel under the amateur built sign according to Mark. If that’s not tripping it’s probably wiring or the regulator.

Some of us had split the system and installed another 60 a breaker for the alternator on the firewall.

N46JP - Q200

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