REFLECTOR: Alternator Field

Wed Apr 27 23:57:40 CDT 2005

Subject: Re: REFLECTOR: Alternator Field

14.2 volts should be fine - the over-voltage trips on high voltage - not 

current.

I'd guess that the circuit breaker is a bit too small (and from your 

symptoms, it sounds like it is on the ragged edge).  The gear pump cycling 

on is probably causing a voltage down spike which is causing a field current

up spike and tripping your 2 amp breaker every once in a while.  If you are 

not replacing the wire, I'd go with a 3 amp breaker.. If you are going to 

replace the wire with 20 gauge, I'd take it on up to 5 amps.

FWIW; A #22 is rated to 5 amps.

Al

I have a 65 amp Lycoming alternator and a VR-600 solid state regulator on a 

5 amp breaker.  Never has tripped.  I bought the parts to build Bob 

Nuckolls' over voltage protection system but never installed it.

Ronnie

----- Original Message ----- 

From: "Rene Dugas" <dugasd at bellsouth.net>

To: "'Velocity Aircraft Owners and Builders list'" <reflector at tvbf.org>

Sent: Wednesday, April 27, 2005 12:57 PM

Subject: RE: REFLECTOR: Alternator Field

> Thanks for the help.

> My CB is 2 amp for field and I use the B & C LR-3 voltage regulator with

> over voltage protection.  My Vision reads 14.2 volts with a max at 14.3

> recorded in the Max screen.  I'm waiting for a call from B& C to discuss

> voltage setting changes and test procedures.  Changing the CB to a 4 or

> 5 amp is a possibility and I can change the wire from a 22 g to 20 g.  I

> do not know how the over voltage system works in the LR-3.  The CB pops

> based on current not voltage Right?  There is an adjustment for voltage

> on the side of the regulator.  Maybe 14.3 volts is too high.  I'll ask.

> Thanks

> Rene'

>

> -----Original Message-----

> From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On

> Behalf Of Jim Sower

> Sent: Tuesday, April 26, 2005 10:20 PM

> To: Velocity Aircraft Owners and Builders list

> Subject: Re: REFLECTOR: Alternator Field

>

> What size circuit breaker on your Alt Fld? Remember, you're not

> protecting the field, you're protecting the field WIRE. The CB should

> pop before the wire melts, but waaay above what the field "should" draw.

>

> Also, how about over voltage protection? What kind do you have?

> Jim S.

>

> Rene Dugas wrote:

>

>> /Dear fellows,/

>>

>> I flew from Houston to north Louisiana on Sunday. My Alt. Field

>> Circuit Breaker opened three times on the flight. The Vision picked it

>

>> up within 3 seconds. I pressed it in again and flew without event for

>> about 30 minutes and it popped again. I noticed that the gear pump

>> cycled at the same time(yellow motor run light momentarily

>> illuminated). I checked the bulbs on the gear indicator and cycled the

>

>> pump without event. No problems for 20 minutes and it popped again.

>> Pushed it in and continued to charge at usual 12 amps. Upon landing no

>

>> problems with gear motor running with strobes and pitot heat on at 47

>> amps. Checked wire to alt. no burns or evidence of short. I've been

>> told the spring in the CB can get weak causing inappropriate opening.

>> I feel this may be related to my pump not being able to spin with

>> significant slack in the gear play causing an electric motor unable to

>

>> move condition causing a high draw condition. Just a feeling. I am not

>

>> an EE! Ideas on order of tests or start replacing parts - CB, wiring,

>> Alt., Etc. Is there a condition in the alternator that will cause this

>

>> and can I check for it? I jacked my plane up and my gear will cycle

>> about each 20 to 30 minutes which matches the frequency of the

>> problem. I can not run it on jacks to test. I had the CB open twice

>> before in 250 hrs and reran the wire. No problem in over 150 hrs.

>>

>> Ideas?

>>

>> /Rene'/

>>

>> / /

>>

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