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Troubleshooting Field Breaker

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piavis(at)comcast.net
Guest

Posted: Mon Apr 02, 2012 7:31 pm Post subject: Troubleshooting Field Breaker

I have the Z-13/8 architecture installed in an RV-7 with the LR-3/ L-60 regulator and alternator (370 hours in 4 years and not one electrical problem). I recently had the aircraft down for conditional inspection and after about 6 weeks started the aircraft, and when the alternator was brought on-line, the field breaker is now popping as soon as the alternator switch is closed. Thinking the battery was potentially shot after leaving the master on last year, I swapped out the PC-680. I pulled down the LR3 troubleshooting guide from B&C and for the most part, everything looks OK with the exception of the Pin 4 voltage being 1.41 volts below the Pin 6, which is .21V out of tolerance (they indicate a delta of 1.2V is expected). I ohm'd out each of the wires and everything is basically 0 ohms across the individual wires including the field wire from Pin 4 out to the alternator. I do have the 5A breaker installed. 

  

I'm starting to scratch my head a bit on troubleshooting the system here, any tips on what else to check? 

  

Thanks, 



Jim 

  

 

 [quote][b]

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Tue Apr 03, 2012 7:55 am Post subject: Re: Troubleshooting Field Breaker

 	  Quote: 	
		  the field breaker is now popping as soon as the alternator switch is closed 	


If I understand correctly, you are turning on the alternator switch AFTER the engine is running.  What happens if the alternator switch is turned on BEFORE starting the engine?  Does the breaker still pop?

  I suggest that the terminals on the voltage regulator be examined carefully to be sure that there is a good tight connection with no corrosion.  Also check that the regulator is well grounded to the system ground bus with no corrosion.

Joe

_________________
Joe Gores

Jim P

Joined: 03 Apr 2012
Posts: 6

Posted: Tue Apr 03, 2012 8:49 am Post subject: Re: Troubleshooting Field Breaker

I've actually tried both ways, and both pop the breaker. The contacts on the LR-3 look good, and all the grounds are good. I did pull the regulator if B&C wanted me to sent it in. 



If not, I may just create jumpers to confirm wiring, but there's always the possibility that the alternator would be bad I suspect.

mapratherid(at)gmail.com
Guest

Posted: Tue Apr 03, 2012 9:54 am Post subject: Troubleshooting Field Breaker

Seems like the field is shorted.  If you disconnect the field wire from the alternator, does it still trip the breaker?  I'm suspicious of a wiring fault. Or possibly a fault in the alternator. 



As another asked, does it only trip with the engine running?

Matt-



On Apr 3, 2012, at 10:49 AM, "Jim P" <piavis(at)comcast.net> wrote:



 	  Quote: 	
		   

 

 I've actually tried both ways, and both pop the breaker. The contacts on the LR-3 look good, and all the grounds are good. I did pull the regulator if B&C wanted me to sent it in. 

 

 If not, I may just create jumpers to confirm wiring, but there's always the possibility that the alternator would be bad I suspect.

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=369957#369957

Jim P

Joined: 03 Apr 2012
Posts: 6

Posted: Tue Apr 03, 2012 10:44 am Post subject: Re: Troubleshooting Field Breaker

Yes, only when the engine is running. It does not trip with battery, and it didn't trip with a power supply attached to the B-lead with engine shut-down.

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Tue Apr 03, 2012 2:17 pm Post subject: Re: Troubleshooting Field Breaker

Since the breaker does not trip when the engine is off (with the alternator switch on), that tells me that the alternator is good and that the regulator and O.V. are not shorted to ground.

  Going by the symptoms that you described, I see 3 possible causes listed in order of likelihood:

1.  High resistance in the voltage regulator sense circuit.  The Alternator switch is one suspect.

2.  Defective voltage regulator.

3.  Defective over-voltage protection.

Let's test for high resistance.  With the engine off and the master and alternator switches on, connect a 35 watt 12V lamp between the regulator Sense terminal and the regulator case (not aircraft ground).  The lamp should illuminate.  Measure the voltage across the lamp.  It should be close to the battery voltage.  If the voltage across the lamp is low, then measure at various points in the Voltage Regulator Sense circuit until the location of the voltage drop is found.

Joe

_________________
Joe Gores

Jim P

Joined: 03 Apr 2012
Posts: 6

Posted: Tue Apr 03, 2012 5:36 pm Post subject: Re: Troubleshooting Field Breaker

I've done some of that troubleshooting. With the Battery / ALT ON at 12.21V, I actually get 12.20 at the OV sense terminal and 10.52V out of terminal #4 which is the field line. Bus voltage into the regulator is 11.93.

user9253

Joined: 28 Mar 2008
Posts: 1921
Location: Riley TWP Michigan

Posted: Tue Apr 03, 2012 8:03 pm Post subject: Re: Troubleshooting Field Breaker

http://www.aeroelectric.com/Mfgr_Data/Regulators/Zeftronics/R15V00_Ford_Style_Reulator.pdf

0.27 volts dropped between the OV sense terminal and VR sense terminal seems high.  There could be a loose connection.  A fully charged battery should have a voltage of about 12.8 volts.

  Attached is a circuit to test the OV protection.  If the aircraft battery voltage is 12.2, connect two flashlight batteries in series with the OV ground wire.  Note the polarity of the flashlight batteries.  I would not expect the OV protection to trip the circuit breaker at 15.4 volts (12.2 + 1.6 + 1.6).  If the OV does trip the breaker, then the OV needs to be adjusted to a higher trip point (16v).

Joe

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_________________
Joe Gores

Jim P

Joined: 03 Apr 2012
Posts: 6

Posted: Wed Apr 04, 2012 11:09 am Post subject: Re: Troubleshooting Field Breaker

Thanks Joe, I'll run that test when I'm back out at the airport.

Jim P

Joined: 03 Apr 2012
Posts: 6

Posted: Sat Apr 07, 2012 12:03 pm Post subject: Re: Troubleshooting Field Breaker

Continued trouble shooting today. Bill at B&C suggested a probable cause of bad field connectors at the alternator. Swapped connectors and all seems fine. Field pin at alternator to ground is 3.5 Ohms so that seems within limits. I ran a jumper wire from the regulator to the field and still see the same issue. I did note that I'm seeing about 15.9 - 16V just before the breaker opens so the alternator seems to be putting out voltage.

nuckolls.bob(at)aeroelect
Guest

Posted: Sat Apr 07, 2012 7:45 pm Post subject: Troubleshooting Field Breaker

At 03:03 PM 4/7/2012, you wrote:

 	  Quote: 	
		  



Continued trouble shooting today. Bill at B&C suggested a probable 

cause of bad field connectors at the alternator. Swapped connectors 

and all seems fine. Field pin at alternator to ground is 3.5 Ohms so 

that seems within limits. I ran a jumper wire from the regulator to 

the field and still see the same issue. I did note that I'm seeing 

about 15.9 - 16V just before the breaker opens so the alternator 

seems to be putting out voltage.


	


   If it is that high, then it seems likely that

   the ov protection system is doing what it was

   designed to do. If regulator portion of the

   LR3 is functioning correctly, then it's being

   mis-informed as to actual bus voltage or perhaps

   it has been adjusted too high.



   One way to sort through all the variables is

   do some testing that is outside the current

   constellation of potential problems.



   I suggest you mail it to B&C. Priority mail

   in a free padded envelope from the post office

   would get it there in a day or two. Same for

   the trip back.



   If the regulator is okay, then this greatly

   simplifies your task.



   Bob . . .

racerjerry

Joined: 15 Dec 2009
Posts: 202
Location: Deer Park, NY

Posted: Sun Apr 08, 2012 6:35 am Post subject: Re: Troubleshooting Field Breaker

[quote="piavis(at)comcast.net"]I recently had the aircraft down for conditional inspection and after about 6 weeks started the aircraft, and when the alternator was brought on-line, the field breaker is now popping as soon as the alternator switch is closed.  

 	  Quote: 	
		  [b] 	




Don’t know if I am reading this correctly.  Could you be saying that this problem occurred immediately after the condition inspection?  If so, it could be a LO-Tech problem, like what was touched / swapped / painted (insulated) / or removed during the inspection.

_________________
Jerry King

Jim P

Joined: 03 Apr 2012
Posts: 6

Posted: Sun Apr 08, 2012 7:44 am Post subject: Re: Troubleshooting Field Breaker

That was the immediate thought, but there really wasn't anything in the system that was touched. Most of the work was in the engine area but didn't include any wiring or alternator work.

Bob McC

Joined: 09 Jan 2006
Posts: 258
Location: Toronto, ON

Posted: Sun Apr 08, 2012 9:07 am Post subject: Troubleshooting Field Breaker

How about something like engine ground strap?? Good clean tight

connections?? Slightly high resistance may not affect cranking but could

mess with voltage measurement by the regulator.



Bob McC



[quote] --

_________________
Bob McC
Falco #908
(just starting)

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