Volatage Regulator Over Voltage Relay

[merrja]

Hi all,

I've been having a few issues that are sporadic with my over voltage light/relay.  The relay keeps popping off (reset by pulling field breaker).  There was a loose wire on the alternator that we thought was the culprit, but after fixing we still have the issue.  Alternator has <500 hours and there is no rhyme or reason to when it pops (load, weather, ect).  For instance I flew 2.5 hours from Ohio and it popped only once, but popped of 6x on a 50 minute flight. 

My thought is to replace both the voltage regulator and the Overvoltage relay...but thought I would consult all the smarter people on Mooney space!

Thoughts?

Thanks!

Jim

[carusoam]

Starting with how old is the relay that keeps popping?

Is it Original equipment?  These things are mechanical devices that have a tendency to wear over time.  They are sensitive to temperature, and get more sensitive over time...   

 

Do you have a JPI or a method to collect voltage data while this event is occurring?

 

What are the choices....?

1) high current... a result of a short... look for frayed wires...

2) high voltage... a result of over charging... a VR problem... easy to see with a volt meter/JPI....

3) worn out CB switch... if neither a high current or high voltage problem actually exists...

 

PP thoughts only.  Check with a mechanic for better details...

Best regards,

-a-

[Yetti]

Breaker could be old.   random popping is usually loose or corroded wires.   rebuild the wiring harness to the alternator.  Could also be worn brushes jumping around on the stator.  Just because wire goes into a lug don't mean it is making good contact.

Edited February 6, 2019 by Yetti

[David Lloyd]

If it is an Interav alternator conversion, I and someone I know had occasional OV trips that a reason never could be found.  I replaced the OV relay with a B&C, never another trip.

[Mark M20B]

I was having an intermittent over voltage issue a few years ago.  Every once in a while my voltage would jump from 14v to 18v and even as high as 24v at times.  When it jumped it would go from being steady to jumping all over the place.  After months of troubleshooting, I found a small loose unused hot wire under the panel that was shorting on the control column.  After removing that wire, I had no more issues.  

[jamesm]

what setup do you have?

I believe '68 was the year they went away from generator.

Alternator/Generator ( I assumed a Alternator) Prestolite/Motorola/InterAv ????

and what Voltage regulator  do you have they can change over time. Delco Remy/ Plane Power/ Zeftronics  /  ????

 

Though you may not have Plane Power  setup ...   a lot of the concepts apply in diagnostic troubleshooting  steps.

Also if you have  original wiring I would look closely to wire end terminations over time the fail this may explain some of the symptoms  of what you are seeing. It probably hasn't become a hard fail yet.

 

https://planepower.aero/aircraft-alternator-support/troubleshooting/

Hope This helps or at least points you in the right direction.

James '67C