Mailing List lml@lancaironline.net Message #61257
From: Charles Patton <charles.r.patton@ieee.org>
Sender: <marv@lancaironline.net>
Subject: Re: [LML] Field breakers popping
Date: Mon, 05 Mar 2012 12:32:21 -0500
To: <lml@lancaironline.net>
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




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