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CIRCUIT BREAKERS

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RV4WGH(at)aol.com
Guest

Posted: Wed Apr 12, 2006 7:59 am Post subject: CIRCUIT BREAKERS

I have a 55 Amp alternator and have been looking for a 60 or 70 Amp -  

push-pull (on-off) circuit breaker. I assume one of those would be the  appropriate 

rating.

 

Anyone know of a source?

 

Thanks,

 

Wally Hunt

Rockford, IL

RV-4 Finishing Kit

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Bruce(at)glasair.org
Guest

Posted: Wed Apr 12, 2006 8:53 am Post subject: CIRCUIT BREAKERS

Use a fuse link instead. If you pop a breaker that size do you really want

to reset it in flight?



Bruce

www.glasair.org

 



--

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nuckollsr(at)cox.net
Guest

Posted: Wed Apr 12, 2006 10:00 am Post subject: CIRCUIT BREAKERS

At 11:55 AM 4/12/2006 -0400, you wrote:



 	  Quote: 	
		  



I have a 55 Amp alternator and have been looking for a 60 or 70 Amp -

push-pull (on-off) circuit breaker. I assume one of those would be 

the  appropriate

rating.



Anyone know of a source?


	


    I'd recommend you go to an ANL current limiter mounted

    on the firewall and wired as described in the Z-figures.



    If you absolutely must have a breaker, the right sized

    (75 amp) is going to be a fat rascal.



    Bob . . .

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Jerry Grimmonpre'

Joined: 09 Jan 2006
Posts: 144
Location: Huntley, Illinois 60142

Posted: Wed Apr 12, 2006 10:38 am Post subject: CIRCUIT BREAKERS

Bruce,

I'm just trying to find a suitable B lead protection with the following 

questions ... no foul intended, Bruce.  Have you used a fuselink for the 

purpose expressed below?  What gage wire are you advocating to use with say, 

a 10 AWG B lead from the alternator?  The standards point to using four 

gages smaller, or, 14 AWG.  Is this what you are advocating to substitute 

for say a 70A CB or 80A current limiter?

Thanks ...

Jerry Grimmonpre'



 	  Quote: 	
		   



 Use a fuse link instead. If you pop a breaker that size do you really want

 to reset it in flight?



 Bruce

 www.glasair.org



 



 I have a 55 Amp alternator and have been looking for a 60 or 70 Amp -

 push-pull (on-off) circuit breaker. I assume one of those would be the

 appropriate

 rating.



 Anyone know of a source?



 Thanks,



 Wally Hunt

 Rockford, IL

 RV-4 Finishing Kit

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nuckollsr(at)cox.net
Guest

Posted: Thu Apr 13, 2006 5:29 am Post subject: CIRCUIT BREAKERS

At 01:36 PM 4/12/2006 -0500, you wrote:



 	  Quote: 	
		  



Bruce,

I'm just trying to find a suitable B lead protection with the following

questions ... no foul intended, Bruce.  Have you used a fuselink for the

purpose expressed below?  What gage wire are you advocating to use with say,

a 10 AWG B lead from the alternator?


	


     When you say 10AWG b-lead feeder, I presume you're talking

     about a SMALL alternator, like the SD20. Here you're talking

     about fusible links on the same order as those used in automobiles

     (14AWG). Yeah, that size b-lead/alternator combination is probably

     a good candidate for fusible link . . . but under the cowl.

 	  Quote: 	
		     The standards . . .


	




     Let's be careful about what we label as "standards" . . . the fusible

     links in automotive applications are common practice supported

     by good science and practical experience. If we elevate the practice

     to a "standard" then the next creep in concept will elevate it to a

     regulation. There are roaming hoards of individuals constantly on the

     lookout for things to elevate to regulatory status all in the name

     of safety . . . and nobody is against being safer, right?



 	  Quote: 	
		    . . . point to using four gages smaller, or, 14 AWG.  Is this what you

  are advocating to substitute for say a 70A CB or 80A current limiter?


	


     Here's where we get a disconnect. A 10AWG/14AWG feeder-link combo

     is in the 20-30A alternator class. If you're looking to replace

     a 70A breaker, then we're talking 6AWG or 4AWG feeders and fusible

     links are indeed impractical. Then the CB or current limiter becomes

     hardware of choice. Since the b-lead protection does not benefit

     from pilot access, a limiter is attractive. Know that limiters

     have a VERY long and conservative operating time constant compared

     with fuses. See:



http://aeroelectric.com/articles/anl/anlvsjjs.html



     Note that a 100A limiter will carry 170A indefinitely

     and that it's blowing time constant is much longer

     than fuses. Breakers fall between fuses and limiters

     with respect to sensitivity and speed.



     Which b-lead are you wrestling with? An SD-20 or something

     larger?



     Bob . . .

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Jerry Grimmonpre'

Joined: 09 Jan 2006
Posts: 144
Location: Huntley, Illinois 60142

Posted: Thu Apr 13, 2006 10:08 am Post subject: CIRCUIT BREAKERS

 	  Quote: 	
		   

 <nuckollsr(at)cox.net>



 At 01:36 PM 4/12/2006 -0500, you wrote:



     When you say 10AWG b-lead feeder, I presume you're talking

     about a SMALL alternator, like the SD20. Here you're talking

     about fusible links on the same order as those used in automobiles

     (14AWG). Yeah, that size b-lead/alternator combination is probably

     a good candidate for fusible link . . . but under the cowl.


	


My bad Bob ...

I erroneously labeled a 60A alt B lead with a 10 AWG and stared at for so 

many days ... began to believe it as well.   It deserves a 6 AWG ... correct 

me if wrong.  In this installation, would a 60A current limiter be OK since 

the CL have an 80% over load rating?



 	  Quote: 	
		   http://aeroelectric.com/articles/anl/anlvsjjs.html


	


Thanks for the link and your leadership, Bob ... that clears up alot.



Jerry Grimmonpre'

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nuckollsr(at)cox.net
Guest

Posted: Thu Apr 13, 2006 4:33 pm Post subject: CIRCUIT BREAKERS

At 01:05 PM 4/13/2006 -0500, you wrote:



 	  Quote: 	
		  





 > 

 > <nuckollsr(at)cox.net>

 >

 > At 01:36 PM 4/12/2006 -0500, you wrote:

 >

 >     When you say 10AWG b-lead feeder, I presume you're talking

 >     about a SMALL alternator, like the SD20. Here you're talking

 >     about fusible links on the same order as those used in automobiles

 >     (14AWG). Yeah, that size b-lead/alternator combination is probably

 >     a good candidate for fusible link . . . but under the cowl.



My bad Bob ...

I erroneously labeled a 60A alt B lead with a 10 AWG and stared at for so

many days ... began to believe it as well.   It deserves a 6 AWG ... correct

me if wrong.  In this installation, would a 60A current limiter be OK since

the CL have an 80% over load rating?



 > http://aeroelectric.com/articles/anl/anlvsjjs.html



Thanks for the link and your leadership, Bob ... that clears up alot.


	


    You're correct. An ANL 60 will be just fine on the b-lead

    of a 60A alternator.



    Bob . . .

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