REFLECTOR: Alternator Field

[Jim Sower]

What size circuit breaker on your Alt Fld? Remember, you're not 
protecting the field, you're protecting the field WIRE. The CB should 
pop before the wire melts, but waaay above what the field "should" draw. 
Also, how about over voltage protection? What kind do you have?
Jim S.

Rene Dugas wrote:

> /Dear fellows,/
>
> I flew from Houston to north Louisiana on Sunday. My Alt. Field 
> Circuit Breaker opened three times on the flight. The Vision picked it 
> up within 3 seconds. I pressed it in again and flew without event for 
> about 30 minutes and it popped again. I noticed that the gear pump 
> cycled at the same time(yellow motor run light momentarily 
> illuminated). I checked the bulbs on the gear indicator and cycled the 
> pump without event. No problems for 20 minutes and it popped again. 
> Pushed it in and continued to charge at usual 12 amps. Upon landing no 
> problems with gear motor running with strobes and pitot heat on at 47 
> amps. Checked wire to alt. no burns or evidence of short. I’ve been 
> told the spring in the CB can get weak causing inappropriate opening. 
> I feel this may be related to my pump not being able to spin with 
> significant slack in the gear play causing an electric motor unable to 
> move condition causing a high draw condition. Just a feeling. I am not 
> an EE! Ideas on order of tests or start replacing parts – CB, wiring, 
> Alt., Etc. Is there a condition in the alternator that will cause this 
> and can I check for it? I jacked my plane up and my gear will cycle 
> about each 20 to 30 minutes which matches the frequency of the 
> problem. I can not run it on jacks to test. I had the CB open twice 
> before in 250 hrs and reran the wire. No problem in over 150 hrs.
>
> Ideas?
>
> /Rene’/
>
> / /
>
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