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Date: Mon, 05 Mar 2012 12:32:21 -0500
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From: Charles Patton <charles.r.patton@ieee.org>
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Subject: Re: [LML] Field breakers popping
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On my 360, a similar condition existed.  Generally after the battery was 
fully charged (leading to a higher impedance for spikes), running the 
hydraulic pump for the gear causes a voltage spike on the charging rail 
when the pump shuts off as the alternator is on high output trying to 
keep the charging rail at nominal voltage with the heavy hydraulic pump 
load.  So as the load drops, the rail shoots up, the overvoltage 
detector crowbars the field breaker line and pops the field breaker.  
This was with a B&C electronic regulator, but I'm assuming you probably 
have a similar regulator.

I typically saw this phenomenon when practicing touch-'n-goes.  The 
important thing was to be checking the field breaker/charging to reset 
it when the condition occurred.  I didn't fix this -- just lived with 
it.   Possibly a fix would be to be sure that you sense the charging 
voltage right on the battery with a "Kelvin" type arrangement (separate 
wire from the regulator sense directly to the battery terminal) so that 
you get the maximum benefit from the spike absorption capability of the 
battery.  This separate wire arrangement is actually the best for 
regulator accuracy as it eliminates the voltage drop of the charging 
current through the wiring from the alternator to the battery.

Regards,
Charles R. Patton   ex-360 owner


On 3/5/2012 5:21 AM, Craig Gainza wrote:
> Dear Listers,
>
> Recently, I completed my annual and test flew the airplane.  Upon 
> lifting the gear both primary and secondary alternator field breakers 
> popped.  Pushed them back in and all charging returned to normal on 
> the primary and secondary alternators.
>
> Landed, checked connections, put in a different battery, ran through B 
> and C voltage regulator troubleshooting guide (came out normal)  and 
> did a ground run up.  When lifting the flaps, hydraulic pump kicked on 
> both field breakers popped again.  Right now I am assuming it is the 
> voltage regulator (both pri and sec are B and C), alternator , or a 
> connector.
>
> Anyone have similar issues and can recommend the next course of action?
>
> Thank you,
>
> Craig Gainza
> IV-P TSIOF 550
>  782 hours and holding
>
>
>