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Bad overvoltage module?

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erich.weaver(at)urs.com
Guest

Posted: Mon Dec 08, 2014 2:01 pm Post subject: Bad overvoltage module?

I have a Z-13/8 electrical system on my RV-7A. While  finishing up a remodel of my panel, I tested my new switches and found that when I turned on the backup PM alternator  with engine off, my 5 amp circuit breaker instantly tripped.  Checked the switch and traced out my wiring and both seem fine,  so I now suspect that either the crowbar over-voltage module or the associated S8005-1 relay from B&C is bad.  I removed the over-voltage  module and my multimeter indicates continuity between the two wires.  Im thinking that should only occur when there is an over-voltage event, so my module must be bad, letting the current bypass the relay altogether and tripping my breaker.  Am I thinking  this through correctly? 

  

Thanks 

  

erich 

  

 

 

    This e-mail and any attachments contain URS Corporation confidential information that may be proprietary or privileged. If you receive this message in error or are not the intended recipient,  you should not retain, distribute, disclose or use any of this information and you should destroy the e-mail and any attachments or copies.       [quote][b]

yellowduckduo(at)gmail.co
Guest

Posted: Mon Dec 08, 2014 2:34 pm Post subject: Bad overvoltage module?

Sounds like a good diagnosis to me Erich.

Especially if the circuit breaker does not trip with the module 

disconnected.

Ken



On 08/12/2014 4:59 PM, Weaver, Erich wrote:

 	  Quote: 	
		  

 I have a Z-13/8 electrical system on my RV-7A. While  finishing up a 

 remodel of my panel, I tested my new switches and found that when I 

 turned on the backup PM alternator with engine off, my 5 amp circuit 

 breaker instantly tripped.  Checked the switch and traced out my 

 wiring and both seem fine,  so I now suspect that either the crowbar 

 over-voltage module or the associated S8005-1 relay from B&C is bad.  

 I removed the over-voltage module and my multimeter indicates 

 continuity between the two wires.  Im thinking that should only occur 

 when there is an over-voltage event, so my module must be bad, letting 

 the current bypass the relay altogether and tripping my breaker.  Am I 

 thinking this through correctly?



 Thanks



 erich

nuckolls.bob(at)aeroelect
Guest

Posted: Mon Dec 08, 2014 2:45 pm Post subject: Bad overvoltage module?

At 15:59 2014-12-08, you wrote:

 	  Quote: 	
		  I have a Z-13/8 electrical system on my RV-7A. While  finishing up a 

remodel of my panel, I tested my new switches and found that when I 

turned on the backup PM alternator with engine off, my 5 amp circuit 

breaker instantly tripped.  Checked the switch and traced out my 

wiring and both seem fine,  so I now suspect that either the crowbar 

over-voltage module or the associated S8005-1 relay from B&C is 

bad.  I removed the over-voltage module and my multimeter indicates 

continuity between the two wires.  Im thinking that should only 

occur when there is an over-voltage event, so my module must be bad, 

letting the current bypass the relay altogether and tripping my 

breaker.  Am I thinking this through correctly?


	


   Sounds right. Did you get it from B&C or from me?

   Doesn't matter. Drop it to me in an envelope and

   I'll repair/replace it as appropriate.



   Bob . . .

erich.weaver(at)urs.com
Guest

Posted: Tue Dec 09, 2014 1:23 pm Post subject: Bad overvoltage module?

Quote:     

I have a Z-13/8 electrical system on my RV-7A. While finishing up a 

 remodel of my panel, I tested my new switches and found that when I 

 turned on the backup PM alternator with engine off, my 5 amp circuit 

 breaker instantly tripped. Checked the switch and traced out my 

 wiring and both seem fine, so I now suspect that either the crowbar 

 over-voltage module or the associated S8005-1 relay from B&C is 

 bad. I removed the over-voltage module and my multimeter indicates 

 continuity between the two wires. Im thinking that should only 

 occur when there is an over-voltage event, so my module must be bad, 

 letting the current bypass the relay altogether and tripping my 

 breaker. Am I thinking this through correctly?      

 



 Sounds right. Did you get it from B&C or from me? 

 Doesn't matter. Drop it to me in an envelope and 

 I'll repair/replace it as appropriate. 

 

 Bob . . . 

  

Thanks guys.  It came from B&C and I went ahead and ordered a replacement from them.  Who knows when it went bad – haven’t had a need to switch on the back up alternator. 

 

I noticed on a OVM doc available on the Aeroelectric Connection website a recommendation that the OVM be checked every year as part of the annual inspection.  Im wondering  if I shouldn’t just remove the OVM entirely.  I should be notified if my voltage starts climbing from my EIS/EFIS warning lights and be able to manually turn off a faulty alternator anyway.  Bad idea? 

  

Erich   

  

 

 

    This e-mail and any attachments contain URS Corporation confidential information that may be proprietary or privileged. If you receive this message in error or are not the intended recipient,  you should not retain, distribute, disclose or use any of this information and you should destroy the e-mail and any attachments or copies.       [quote][b]

email(at)jaredyates.com
Guest

Posted: Tue Dec 09, 2014 2:45 pm Post subject: Bad overvoltage module?

I'd vote for bad idea! You might browse through Chapter 6 of the AEC again

nuckolls.bob(at)aeroelect
Guest

Posted: Tue Dec 09, 2014 5:53 pm Post subject: Bad overvoltage module?

 	  Quote: 	
		  Thanks guys.  It came from B&C and I went ahead and ordered a replacement from them.  Who knows when it went bad – haven’t had a need to switch on the back up alternator. 	


   I'd still like to get the bad one even if

   you don't want it back.



 

 

   Bob . . .    [quote][b]

ceengland7(at)gmail.com
Guest

Posted: Tue Dec 09, 2014 7:00 pm Post subject: Bad overvoltage module?

On 12/9/2014 3:18 PM, Weaver, Erich       wrote:

     

      	  Quote: 	
		                         <![endif]-->   <![endif]-->                                                                                           

Quote:                                                                                   

I                       have a Z-13/8 electrical system on my RV-7A. While                       finishing up a                       

                       remodel of my panel, I tested my new switches and                       found that when I 

                       turned on the backup PM alternator with engine                       off, my 5 amp circuit 

                       breaker instantly tripped. Checked the switch and                       traced out my 

                       wiring and both seem fine, so I now suspect that                       either the crowbar 

                       over-voltage module or the associated S8005-1                       relay from B&C is 

                       bad. I removed the over-voltage module and my                       multimeter indicates 

                       continuity between the two wires. Im thinking that                       should only 

                       occur when there is an over-voltage event, so my                       module must be bad, 

                       letting the current bypass the relay altogether                       and tripping my 

                       breaker. Am I thinking this through correctly?                                                                  

         



               Sounds right. Did you get it from B&C or from me? 

               Doesn't matter. Drop it to me in an envelope and 

               I'll repair/replace it as appropriate. 

               

               Bob . . .         

          

Thanks guys.  It came from B&C               and I went ahead and ordered a replacement from them.  Who               knows when it went bad – haven’t had a need to switch on               the back up alternator.         

         

I noticed on a OVM doc available on               the Aeroelectric Connection website a recommendation that               the OVM be checked every year as part of the annual               inspection.  Im wondering if I shouldn’t just remove the               OVM entirely.  I should be notified if my voltage starts               climbing from my EIS/EFIS warning lights and be able to               manually turn off a faulty alternator anyway.  Bad idea?         

          

Erich           

 

                

     	
     Only snag with that plan is if the failure happens while the pilot     is in a high-workload situation. If the pilot doesn't react quickly     enough, he could lose all the avionics to overvoltage just when he     needs them most.

      [quote][b]

email(at)jaredyates.com
Guest

Posted: Tue Dec 09, 2014 7:26 pm Post subject: Bad overvoltage module?

In AEC v12, page 6-7, Bob explains that the Crowbar OV module is designed to work on a 5 millisecond interval.Â  I don't think it matters much what the pilot's workload is, he or she is not going to beat 5 milliseconds!Â  Also on that page and the page before, he writes about how the method that the crowbar system uses to disconnect the circuit is special, so that it doesn't break an inductive circuit.Â  It's a really good chapter that makes the case for why the Crowbar OVM is important.Â  I would copy and paste it, but in version 12, those pages are optically scanned.



  [quote][b]

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Wed Dec 10, 2014 7:10 am Post subject: Re: Bad overvoltage module?

I agree with others that not having over-voltage protection is a bad idea.  High voltage can damage expensive avionics in much less time than a human can react to shut it off.

_________________
Joe Gores

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Wed Dec 10, 2014 7:21 am Post subject: Re: Bad overvoltage module?

 	  Quote: 	
		  when I turned on the backup PM alternator with engine off, my 5 amp circuit breaker instantly tripped. 	


With the over-voltage module removed from the circuit, does the relay energize (click) when the aux alt switch is turned on?  And does the circuit breaker not trip?  If both true, then the fault must be the O.V. module.

Joe

_________________
Joe Gores

ChasB(at)satx.rr.com
Guest

Posted: Wed Dec 10, 2014 8:09 am Post subject: Bad overvoltage module?

I noted the recommendation that the OVM be checked annually. I have not done that in the nearly eight years my RV has been flying. Nor has the OVM ever shut down the alternator. Nor have I had any voltage surge that damaged anything. Just lucky?



What is the best (easiest) method to check the OVM operation?



Charlie Brame

RV-6A  N11CB

San Antonio

user9253

Joined: 28 Mar 2008
Posts: 1908
Location: Riley TWP Michigan

Posted: Wed Dec 10, 2014 11:09 am Post subject: Re: Bad overvoltage module?

 	  Quote: 	
		  What is the best (easiest) method to check the OVM operation? 	


Page 1 of his document http://www.aeroelectric.com/DIY/DIY_Crowbar_OVP_F.pdf

shows how to test an over-voltage module.  The best way is on a workbench using an adjustable DC power supply.  The easy way is in the aircraft using alligator clips and a battery.  Bob says to use a 6 volt lantern battery, but 4 D cells in series might work too.  Notice that the negative alligator clip is attached to the aircraft power bus.  I recommend that all avionics and any polarity sensitive devices be shut off prior to doing this test.

Joe

_________________
Joe Gores

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