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Pullable 60 Amp Breaker

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Tim_Lewis(at)msm.umr.edu
Guest

Posted: Sun Nov 18, 2007 6:05 pm Post subject: Pullable 60 Amp Breaker

Over the years I've looked without success for a pullable 60 Amp breaker.  The other day I noticed one in a friend's Glastar (an early two-weeks-to-taxi pathfinder).  I crawled under the panel, jotted down the part number, and found several sources on the net.  The part number is 413-K14-LN2, made by ETA.  I bought one from Pacific Coast Avionics (part number "ETA-60".  They have a 75 Amp version, too.

 

 Use with caution, of course.  Pulling the breaker when the alternator is putting out significant current can ruin the alternator (V = L*di/dt, I suppose).

 

 [img]cid:part1.03070702.07050801(at)msm.umr.edu[/img]

  	  Quote: 	
		  

-- 

Tim Lewis -- HEF (Manassas, VA)

RV-6A N47TD -- 900 hrs

RV-10 #40059 under construction

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longg(at)pjm.com
Guest

Posted: Mon Nov 19, 2007 6:02 am Post subject: Pullable 60 Amp Breaker

Great  find but an ANL fuse will offer the same protection and keep you or a curious  passenger from ruining your alternator. Not to mention it cost about 1/10 of  that breaker. Why are you so interested in isolating your alternator? When my  alternator fails it doesn't run a-muck in the engine compartment and burst into  flames, it simply becomes another lawn ornament.

 [quote]   

   --

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nuckolls.bob(at)cox.net
Guest

Posted: Mon Nov 19, 2007 7:20 am Post subject: Pullable 60 Amp Breaker

At 08:58 AM 11/19/2007 -0500, you wrote:



This thread has stirred a lot of concerns together which

I will attempt to put into perspective.



First, know that designers of upper-end production aircraft

have made a effort to get high-current, noise-carrying

conductors off the panel. The alternator is the strongest

noise source on the bus and it's b-lead is the strongest

emitter of magnetically coupled noise in the airplane. Hence,

a migration of b-lead protection out of the cockpit and onto

the firewall as seen here . . .



http://www.aeroelectric.com/Pictures/Wiring_Technique/Firewall_Ckt_Protection.jpg



Second, I cringe when concerns for the actions of

"curious passengers" are raised as drivers for how a

cockpit is laid out or fitted . . . I've flown hundreds

of passengers and never have I had to admonish anyone

to "not touch that". There would be only ONE time

that I might have to educate someone on passenger cockpit

etiquette. The second incident would result in a dispatched

return to the field and a polite request that the individual

exit the aircraft.



Third, it has been suggested that a breaker might serve

as the last-ditch means by which a pilot can bring a runaway

alternator to heel . . . or at least disconnect it from the

system. This logic is flawed for several reasons: (1) breakers

are designed to disconnect hard downstream faults in a system

where the voltage are on the order of 32 volts or less. (2)

A runaway alternator is capable of raising the b-lead terminal

to hundreds of volts in milliseconds where it is NOT reasonable

to expect the breaker to also serve as a SWITCH for reliable

disconnect of the offending alternator. Any attempt to use

a breaker (particularly a miniature one with plastic housing!)

for this purpose is to flirt with probability of cockpit fire

and much smoke.



Finally, know that a 60A breaker on a 60A alternator is

DESIGNED to nuisance trip.  The b-lead protection on an alternator

should stay closed at current levels perhaps 20% higher than

the nameplate rating of the alternator. The GA spam-can community

really blew it when 60A b-lead breakers were installed in 100,000+

aircraft with 60A alternators.



The ideas cited above are drivers for my personal design

goals that strive to (1) move b-leads out of the cockpit and

(2) supply any-time, any-conditions, positive ON-OFF control

of all energy sources to the aircraft crew.



Of course, we're free to establish and satisfy any alternative

design goals. Incorporation of the 60A, panel mounted,

pullable breaker to satisfy the goals cited is, in my humble

opinion, ignoring a lot of experience and thoughtful reasoning

suggesting that panel a mounted, b-lead breaker is not the

best-we-know-how-to-do.



Bob . . .



[quote]Great find but an ANL fuse will offer the same protection and keep you or 

a curious passenger from ruining your alternator. Not to mention it cost 

about 1/10 of that breaker. Why are you so interested in isolating your 

alternator? When my alternator fails it doesn't run a-muck in the engine 

compartment and burst into flames, it simply becomes another lawn ornament.

--

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klehman(at)albedo.net
Guest

Posted: Mon Nov 19, 2007 3:12 pm Post subject: Pullable 60 Amp Breaker

In addition to other concerns, if they are push on connections, I'd 

would not expect them to stand up to 60+ amps very long.  Can you even 

get push on connectors for awg 6 wire?

Ken



Tim Lewis wrote:



 	  Quote: 	
		   Over the years I've looked without success for a pullable 60 Amp 

 breaker.  The other day I noticed one in a friend's Glastar (an early 

 two-weeks-to-taxi pathfinder).  I crawled under the panel, jotted down 

 the part number, and found several sources on the net.  The part 

 number is 413-K14-LN2, made by ETA.  I bought one from Pacific Coast 

 Avionics (part number "ETA-60".  They have a 75 Amp version, too.



 Use with caution, of course.  Pulling the breaker when the alternator 

 is putting out significant current can ruin the alternator (V = 

 L*di/dt, I suppose).



-- 

Tim Lewis -- HEF (Manassas, VA)

RV-6A N47TD -- 900 hrs

RV-10 #40059 under construction

Tim_Lewis(at)msm.umr.edu
Guest

Posted: Mon Nov 19, 2007 4:52 pm Post subject: Pullable 60 Amp Breaker

The breaker  uses a 3/8" screw (huge flat head) on both lugs. 



Tim



-- 

Tim Lewis -- HEF (Manassas, VA)

RV-6A N47TD -- 975 hrs

RV-10 #40059 under construction



Ken wrote:

 	  Quote: 	
		   



 In addition to other concerns, if they are push on connections, I'd 

 would not expect them to stand up to 60+ amps very long.  Can you even 

 get push on connectors for awg 6 wire?

 Ken



 Tim Lewis wrote:



> Over the years I've looked without success for a pullable 60 Amp 

> breaker.  The other day I noticed one in a friend's Glastar (an early 

> two-weeks-to-taxi pathfinder).  I crawled under the panel, jotted 

> down the part number, and found several sources on the net.  The part 

> number is 413-K14-LN2, made by ETA.  I bought one from Pacific Coast 

> Avionics (part number "ETA-60".  They have a 75 Amp version, too.

>

> Use with caution, of course.  Pulling the breaker when the alternator 

> is putting out significant current can ruin the alternator (V = 

> L*di/dt, I suppose).

>

gmcjetpilot

Joined: 04 Nov 2006
Posts: 170

Posted: Tue Nov 20, 2007 1:24 pm Post subject: Pullable 60 Amp Breaker

 	  Quote: 	
		  From: "Robert L. Nuckolls, III" <nuckolls.bob(at)cox.net (nuckolls.bob(at)cox.net)> 

Subject: RE: Pullable 60 Amp Breaker 

 	  Quote: 	
		  First, know that designers of upper-end production aircraft 

have made a effort to get high-current, noise-carrying 

conductors off the panel.

  Never heard noise in my plane with B-lead CB in panel. 

I would just say prove it. Modern internally regulated alternators 

are not noisy so it's a moot point. Old Gen from days gone by, yes 

noisy.

  >Second, I cringe when concerns for the actions of 

 	  Quote: 	
		  "curious passengers" are raised as drivers for how a 

cockpit is laid out or fitted . . . 

  You are stretching. Does the passenger have a control 

yoke or stick they could shove right after takeoff or 

right before landing? No Bozo allowed.

 	  Quote: 	
		  Third, it has been suggested that a breaker might serve 

as the last-ditch means by which a pilot can bring a runaway 

alternator to heel . . . or at least disconnect it from the 

system. This logic is flawed for several reasons: (1) breakers 

are designed to disconnect hard downstream faults in a system 

where the voltage are on the order of 32 volts or less. (2) 

A runaway alternator is capable of raising the b-lead terminal 

to hundreds of volts in milliseconds where it is NOT reasonable 

to expect the breaker to also serve as a SWITCH for reliable 

disconnect of the offending alternator. Any attempt to use 

a breaker (particularly a miniature one with plastic housing!) 

or this purpose is to flirt with probability of cockpit fire 

and much smoke.

  With all due respect I think your logic is flawed. It may fit for external 

regulated  alternators but not for internally regulated ones. 

  A CB is RATED to disconnect at 32volts many many times, however 

it can handle much more. No I don't have an absolute number but 

when most 12 volt alternators with a so called over voltage rarely 

exceeds 17 v much less 32 v, your point is moot, 32v good enough.

  When you say 100's of VOLTS and Cockpit FIRE, it's fear mongering 

not based on facts. Science and engineering are based on facts not 

emotional reasons. CB catch on fire? Really? OK, prove it.

  Small 40 / 60 amp alternators are not pumping 100's of volts or amps.

Internally regulated alternators typically go to 16 or 17 volts, if 

regulation fails, easily controlled by a CB. Yes there may have 

been one "screw lose" case where voltage was truly out of control, 

but it's rare, and the voltage was undetermined. I  doubt it got to 

over 32 volts. 

  Also an ANL fuse will not blow with 100's of volts, it's a current 

device. If you want to wire your airplane like a Toyota with fuses, fine,

but there is no need to make stuff up against CB's in the panel. 

 	  Quote: 	
		  Finally, know that a 60A breaker on a 60A alternator is 

DESIGNED to nuisance trip. The b-lead protection on an alternator 

should stay closed at current levels perhaps 20% higher than 

the nameplate rating of the alternator. The GA spam-can community 

really blew it when 60A b-lead breakers were installed in 100,000+ 

aircraft with 60A alternators.

  Easily solved by sizing the CB properly. I guess they don't have 

smart people working for the GA spam-can community. Frankly CB's 

can take slight overloads for a period of time with out a trip. Again 

moot point Bob, if the alternator can  only put out 45 amps.

  >In my humble opinion, ignoring a lot of experience and 

 	  Quote: 	
		  thoughtful reasoning suggesting that panel a mounted, b-lead 

breaker is not the best-we-know-how-to-do. 

Bob . . .

  What?

  Fuses are fine. Buth with (stock) internal regulation the CB is a good 

reason to use a B-lead CB. Other engineers have worked on this 

Bob. The pull-able CB for the B-lead is specified. It's irresponsible of 

you to be so stubborn and opinionated, making ONE blanked edict 

that one size fits all. Fuses are not a BE ALL solution for every 

application. Follow the manufactures recommendation!

  In my humble opinion, I disagree with Bob with my thoughtful reasoning 

and facts. I don't care what you use but know why you are using it. I 

don't believe you will have noise or won't be able to disconnect the  

b-lead manually if you want to. When people talk 100's of volts & fire 

they are exaggerating in non-scientific emotional arguments, not 

engineering. Have Bob prove these are real problems. I could come 

up with lots of NIT PICK reasons a fuse really is a poor choice.

Cheers George

        [quote][b]

schaefer(at)rts-services.
Guest

Posted: Tue Nov 20, 2007 2:16 pm Post subject: Pullable 60 Amp Breaker

Why would anyone want to reset a tripped 60A breaker in flight ?   

If you want to disable the alternator than switching off the alternator field would generate a lot less transients that components have to deal with.  

   

   

   

       [quote][b]

nuckolls.bob(at)cox.net
Guest

Posted: Wed Nov 21, 2007 3:15 pm Post subject: Pullable 60 Amp Breaker

Date: Tue, 20 Nov 2007 13:23:04 -0800 (PST)

From: <gmcjetpilot(at)yahoo.com>

Subject: RE: Pullable 60 Amp Breaker

To: aeroelectric-list(at)matronics.com



 	  Quote: 	
		  

 >First, know that designers of upper-end production aircraft

 >have made a effort to get high-current, noise-carrying

 >conductors off the panel.



Never heard noise in my plane with B-lead CB in panel.

I would just say prove it. Modern internally regulated alternators

are not noisy so it's a moot point. Old Gen from days gone by, yes

noisy.


	


    George, this has nothing to do with the style of

    regulator. 3-phase rectified AC has a 5% built-in ripple

    component that is a physical artifact of the product.

    I've encountered magnetically coupled noises in both

    automobiles and aircraft. So your statement about "modern

    internally regulated alternators not being noisy" is

    demonstrably in error and your admonition to "prove it"

    is a manifestation of your proven history of inability

    or unwillingness to carry on discussions based on

    physics and simple-ideas.



    I've troubleshot and fixed a number of magnetically

    coupled alternator whine problems on aircraft and once

    in my own automobile. It's doubtful that any demonstration

    would be sufficient "proof" to make this phenomenon

    real and significant in your limited understanding.

    Alternators are much more noisy than generators.

 	  Quote: 	
		   >Third, it has been suggested that a breaker might serve

 >as the last-ditch means by which a pilot can bring a runaway

 >alternator to heel . . . or at least disconnect it from the

 >system. This logic is flawed for several reasons: (1) breakers

 >are designed to disconnect hard downstream faults in a system

 >where the voltage are on the order of 32 volts or less. (2)

 >A runaway alternator is capable of raising the b-lead terminal

 >to hundreds of volts in milliseconds where it is NOT reasonable

 >to expect the breaker to also serve as a SWITCH for reliable

 >disconnect of the offending alternator. Any attempt to use

 >a breaker (particularly a miniature one with plastic housing!)

 >or this purpose is to flirt with probability of cockpit fire

 >and much smoke.



With all due respect I think your logic is flawed. It may fit for external

regulated alternators but not for internally regulated ones.


	


    It matters not what style of alternator is being

    considered, any alternator running self-excited by

    a field voltage which is a product of it's own output

    is capable of well over 100 volts of output. See:



http://aeroelectric.com/articles/When_is_110V_not_Over_Voltage.pdf



 	  Quote: 	
		  

A CB is RATED to disconnect at 32 volts many many times, however

it can handle much more. No I don't have an absolute number but

when most 12 volt alternators with a so called over voltage rarely

exceeds 17 v much less 32 v, your point is moot, 32v good enough.


	


    Yes, the runaway alternators that were NOT putting out

    hundreds of volts were being loaded by a battery that

    was dutifully sacrificing itself by accepting what the

    alternator could deliver due to its inherent current

    limiting.



    But the very act of opening the b-lead on a runaway

    alternator disconnects the battery and all other parts

    of the ship's systems. As soon as the contacts of the

    'switch' open, the alternator becomes unrestrained and

    b-lead voltage will rise rapidly to values much greater

    than the 32-volt rating of the breaker. Once you strike

    the arc between the opening contacts, one has 100+

    volts at 40-60 amps (4,000+ watts) of potential power

    being dumped into the fire. This would probably be

    contained by an all-metal enclosure like:



http://www.aeroelectric.com/Pictures/Contactors/s701-1.jpg



    but enclosures like this . . .



http://www.aeroelectric.com/Pictures/Contactors/6041_Contactor.jpg



    . . . have proven incapable of containing such fires



http://www.aeroelectric.com/Pictures/Failures/6041_Contactor_Failure.jpg



 	  Quote: 	
		  

When you say 100's of VOLTS and Cockpit FIRE, it's fear mongering

not based on facts. Science and engineering are based on facts not

emotional reasons. CB catch on fire? Really? OK, prove it.


	


    It is an absolute certainty that an enclosure like this



http://www.aeroelectric.com/Pictures/Breakers/circuitbreakers.jpg



    will not contain such fires either.



 	  Quote: 	
		  

Small 40 / 60 amp alternators are not pumping 100's of volts or amps.

Internally regulated alternators typically go to 16 or 17 volts, if

regulation fails, easily controlled by a CB. Yes there may have

been one "screw lose" case where voltage was truly out of control,

but it's rare, and the voltage was undetermined. I doubt it got to

over 32 volts.


	


    As soon as the runaway alternator is disconnected from

    the system by pulling a breaker, the battery is relieved

    of sacrificial duties and the voltage at the alternator's

    b-lead will rise rapidly and to magnitudes previously cited. . .

    the Mother of All Load Dumps.



 	  Quote: 	
		  

Also an ANL fuse will not blow with 100's of volts, it's a current

device. If you want to wire your airplane like a Toyota with fuses, fine,

but there is no need to make stuff up against CB's in the panel.


	


   Fuses are not expected to protect against over-voltage events

   but over-current events. Know that a runaway alternator has

   NEVER put out more current that what's established by the

   physics of it's magnetics. I.e, not enough to open the

   b-lead protection irrespective of it's design (assuming

   it is sized for sufficient headroom to avoid nuisance

   tripping). Nonetheless, bus voltages are carried upward

   to many times greater than normal bus voltage unless

   some well considered means for stopping it has been included

   in the design.

 	  Quote: 	
		   >Finally, know that a 60A breaker on a 60A alternator is

 >DESIGNED to nuisance trip. The b-lead protection on an alternator

 >should stay closed at current levels perhaps 20% higher than

 >the nameplate rating of the alternator. The GA spam-can community

 >really blew it when 60A b-lead breakers were installed in 100,000+

 >aircraft with 60A alternators.



Easily solved by sizing the CB properly. I guess they don't have

smart people working for the GA spam-can community. Frankly CB's

can take slight overloads for a period of time with out a trip. Again

moot point Bob, if the alternator can only put out 45 amps.


	


    That's what I said. The 60A breaker is too small for

    being used with a 60A alternator. Yes, MOST nuisance

    tripping is avoided by the noteworthy time delays

    inherent in the design of CBs . . . but the majority

    of nuisance trips of breakers in light aircraft are

    the 60A b-lead breaker tied to a 60A alternator.



    Your off-hand comment about the intelligence of folks

    working in GA is uncalled for and yet another manifestation

    of your long and oft demonstrated history of belligerent,

    ill-informed, nay ignorant participation on this List.

    There are MANY folks within GA that would very much

    like to rectify the condition cited . . . but it's never

    bubbled to the top-ten-problems list with an airframe OEM and

    the FAA makes it insanely $difficult$ to make even the

    simplest changes. Hence, this marginal design has

    endured for decades more out of resignation to the

    authority of a higher power than of ignorance or apathy.

 	  Quote: 	
		   >In my humble opinion, ignoring a lot of experience and

 >thoughtful reasoning suggesting that panel a mounted, b-lead

 >breaker is not the best-we-know-how-to-do.

 >Bob . . .



What?



Fuses are fine. Buth with (stock) internal regulation the CB is a good

reason to use a B-lead CB. Other engineers have worked on this

Bob. The pull-able CB for the B-lead is specified. It's irresponsible of

you to be so stubborn and opinionated, making ONE blanked edict

that one size fits all. Fuses are not a BE ALL solution for every

application. Follow the manufactures recommendation!


	


   This isn't a fuses/breakers discussion, it's

   an examination of the physics which govern assembly

   of some exceedingly simple ideas into recipes for

   success with an acknowledgment of hazards which

   should be considered as part of a thoughtful design.



 	  Quote: 	
		  

In my humble opinion, I disagree with Bob with my thoughtful reasoning

and facts. I don't care what you use but know why you are using it. I

don't believe you will have noise or won't be able to disconnect the

b-lead manually if you want to. When people talk 100's of volts & fire

they are exaggerating in non-scientific emotional arguments, not

engineering. Have Bob prove these are real problems. I could come

up with lots of NIT PICK reasons a fuse really is a poor choice.


	


    George, you have been politely requested to keep

    your comments on this topic to yourself . . . they've

    been read many times for years on this List and debunked

    as recorded and published at:



http://www.aeroelectric.com/articles/gmcjetpilot.html



http://aeroelectric.com/articles/The_Truth_about_Crowbar_OV_Protection.pdf



    You have designed nothing, fixed nothing, contributed

    nothing to the understanding of physics, serviced no

    customers, taught no classes, or offered a 100% satisfaction

    assured warranty for your products. Yet you persist

    in lurking at the edges of a sandbox not of your

    construction to throw rocks and mud while hiding behind

    a pseudonym decorated with much alphabet soup of

    self proclaimed titles/accolades. You claim superior

    engineering insight while never having demonstrated

    it with useful work-product.



    I've demonstrated/experienced/explained every assertion

    I've ever made based on my hands-on experiences with these

    systems since I did my first OV relay design for Cessna

    Aircraft in 1975. Your belittling diatribes and circular

    arguments contribute nothing to the advancement of

    our science, understanding or art and yet you deign to

    call me a liar. Your brand of 'science' is not welcome

    in this classroom. You sir are the secretive, fraudulent

    participant in these discussions and I will ask you

    politely for the third or forth time, please go away.



    Bob . . .



       (---------------------------------------)

       ( . . . a long habit of not thinking    )

       ( a thing wrong, gives it a superficial )

       ( appearance of being right . . .       )

       (                                       )

       (                 -Thomas Paine 1776-   )

       (---------------------------------------)

nuckolls.bob(at)cox.net
Guest

Posted: Wed Nov 21, 2007 3:52 pm Post subject: Pullable 60 Amp Breaker

At 04:12 PM 11/20/2007 -0600, you wrote:



 	  Quote: 	
		  Why would anyone want to reset a tripped 60A breaker in flight ?



If you want to disable the alternator than switching off the alternator 

field would generate a lot less transients that components have to deal with.


	


    Yes, you'll have to research this topic in the

    archives a bit. It's not about whether or not

    one should 'reset' a tripped breaker but one

    of selecting design goals. I.e, is it (1)

    reasonable to assume an alternator with a "broken"

    internal regulator can be depended upon to

    remain at or below 17 volts and (2)

    depend on a panel mounted b-lead breaker

    to disconnect said alternator from the bus

    after (3) the pilot becomes aware of the OV

    condition.



    It has been suggested that this design

    goal is a suitable alternative to architectures

    and goals embraced by the vast majority

    of the TC aviation community.



    Bob . . .

        ----------------------------------------)

        ( . . .  a long habit of not thinking   )

        ( a thing wrong, gives it a superficial )

        ( appearance of being right . . .       )

        (                                       )

        (                  -Thomas Paine 1776-  )

        ----------------------------------------

medorrisjr(at)hotmail.com
Guest

Posted: Wed Nov 21, 2007 5:46 pm Post subject: Pullable 60 Amp Breaker

With several hundred, uh thousands (they become blurred and seemingly insignificant)  of flight hours I now attempt a life-long goal of building my own airplane.  My self-professed weakness is wiring, electronics and electricity in general.  Thus, my reason for joining this forum.  I read every post with an open mind and hopefully add to my limited understanding of the traveling electron.

  

 In following this thread of "Pullable 60 Amp Breaker" I am reminded of something I learned a long time ago.  The only difference between a jet pilot and a jet engine is the fact that a jet engine stops whining when you shut it down.

 Happy Thanksgiving & Best Regards to all,

 Marvin

  

 



e: Wed, 21 Nov 2007 17:08:17 -0600

 	  Quote: 	
		   To: aeroelectric-list(at)matronics.com

 From: nuckolls.bob(at)cox.net

 Subject: Re: AeroElectric-List: RE: Pullable 60 Amp Breaker

 

 --> AeroElectric-List message posted by: "Robert L. Nuckolls, III" <nuckolls.bob(at)cox.net>

 

 

 

 

 Date: Tue, 20 Nov 2007 13:23:04 -0800 (PST)

 From: <gmcjetpilot(at)yahoo.com>

 Subject: RE: Pullable 60 Amp Breaker

 To: aeroelectric-list(at)matronics.com

 

 >

 > >First, know that designers of upper-end production aircraft

 > >have made a effort to get high-current, noise-carrying

 > >conductors off the panel.

 >

 >Never heard noise in my plane with B-lead CB in panel.

 >I would just say prove it. Modern internally regulated alternators

 >are not noisy so it's a moot point. Old Gen from days gone by, yes

 >noisy.

 

 George, this has nothing to do with the style of

 regulator. 3-phase rectified AC has a 5% built-in ripple

 component that is a physical artifact of the product.

 I've encountered magnetically coupled noises in both

 automobiles and aircraft. So your statement about "modern

 internally regulated alternators not being noisy" is

 demonstrably in error and your admonition to "prove it"

 is a manifestation of your proven history of inability

 or unwillingness to carry on discussions based on

 physics and simple-ideas.

 

 I've troubleshot and fixed a number of magnetically

 coupled alternator whine problems on aircraft and once

 in my own automobile. It's doubtful that any demonstration

 would be sufficient "proof" to make this phenomenon

 real and significant in your limited understanding.

 Alternators are much more noisy than generators.

 

 

 > >Third, it has been suggested that a breaker might serve

 > >as the last-ditch means by which a pilot can bring a runaway

 > >alternator to heel . . . or at least disconnect it from the

 > >system. This logic is flawed for several reasons: (1) breakers

 > >are designed to disconnect hard downstream faults in a system

 > >where the voltage are on the order of 32 volts or less. (2)

 > >A runaway alternator is capable of raising the b-lead terminal

 > >to hundreds of volts in milliseconds where it is NOT reasonable

 > >to expect the breaker to also serve as a SWITCH for reliable

 > >disconnect of the offending alternator. Any attempt to use

 > >a breaker (particularly a miniature one with plastic housing!)

 > >or this purpose is to flirt with probability of cockpit fire

 > >and much smoke.

 >

 >With all due respect I think your logic is flawed. It may fit for external

 >regulated alternators but not for internally regulated ones.

 

 It matters not what style of alternator is being

 considered, any alternator running self-excited by

 a field voltage which is a product of it's own output

 is capable of well over 100 volts of output. See:

 

 http://aeroelectric.com/articles/When_is_110V_not_Over_Voltage.pdf

 

 >

 >A CB is RATED to disconnect at 32 volts many many times, however

 >it can handle much more. No I don't have an absolute number but

 >when most 12 volt alternators with a so called over voltage rarely

 >exceeds 17 v much less 32 v, your point is moot, 32v good enough.

 

 Yes, the runaway alternators that were NOT putting out

 hundreds of volts were being loaded by a battery that

 was dutifully sacrificing itself by accepting what the

 alternator could deliver due to its inherent current

 limiting.

 

 But the very act of opening the b-lead on a runaway

 alternator disconnects the battery and all other parts

 of the ship's systems. As soon as the contacts of the

 'switch' open, the alternator becomes unrestrained and

 b-lead voltage will rise rapidly to values much greater

 than the 32-volt rating of the breaker. Once you strike

 the arc between the opening contacts, one has 100+

 volts at 40-60 amps (4,000+ watts) of potential power

 being dumped into the fire. This would probably be

 contained by an all-metal enclosure like:

 

 http://www.aeroelectric.com/Pictures/Contactors/s701-1.jpg

 

 but enclosures like this . . .

 

 http://www.aeroelectric.com/Pictures/Contactors/6041_Contactor.jpg

 

 . . . have proven incapable of containing such fires

 

 http://www.aeroelectric.com/Pictures/Failures/6041_Contactor_Failure.jpg

 

 

 

 >

 >When you say 100's of VOLTS and Cockpit FIRE, it's fear mongering

 >not based on facts. Science and engineering are based on facts not

 >emotional reasons. CB catch on fire? Really? OK, prove it.

 

 It is an absolute certainty that an enclosure like this

 

 http://www.aeroelectric.com/Pictures/Breakers/circuitbreakers.jpg

 

 will not contain such fires either.

 

 >

 >Small 40 / 60 amp alternators are not pumping 100's of volts or amps.

 >Internally regulated alternators typically go to 16 or 17 volts, if

 >regulation fails, easily controlled by a CB. Yes there may have

 >been one "screw lose" case where voltage was truly out of control,

 >but it's rare, and the voltage was undetermined. I doubt it got to

 >over 32 volts.

 

 As soon as the runaway alternator is disconnected from

 the system by pulling a breaker, the battery is relieved

 of sacrificial duties and the voltage at the alternator's

 b-lead will rise rapidly and to magnitudes previously cited. . .

 the Mother of All Load Dumps.

 

 >

 >Also an ANL fuse will not blow with 100's of volts, it's a current

 >device. If you want to wire your airplane like a Toyota with fuses, fine,

 >but there is no need to make stuff up against CB's in the panel.

 

 Fuses are not expected to protect against over-voltage events

 but over-current events. Know that a runaway alternator has

 NEVER put out more current that what's established by the

 physics of it's magnetics. I.e, not enough to open the

 b-lead protection irrespective of it's design (assuming

 it is sized for sufficient headroom to avoid nuisance

 tripping). Nonetheless, bus voltages are carried upward

 to many times greater than normal bus voltage unless

 some well considered means for stopping it has been included

 in the design.

 

 

 > >Finally, know that a 60A breaker on a 60A alternator is

 > >DESIGNED to nuisance trip. The b-lead protection on an alternator

 > >should stay closed at current levels perhaps 20% higher than

 > >the nameplate rating of the alternator. The GA spam-can community

 > >really blew it when 60A b-lead breakers were installed in 100,000+

 > >aircraft with 60A alternators.

 >

 >Easily solved by sizing the CB properly. I guess they don't have

 >smart people working for the GA spam-can community. Frankly CB's

 >can take slight overloads for a period of time with out a trip. Again

 >moot point Bob, if the alternator can only put out 45 amps.

 

 That's what I said. The 60A breaker is too small for

 being used with a 60A alternator. Yes, MOST nuisance

 tripping is avoided by the noteworthy time delays

 inherent in the design of CBs . . . but the majority

 of nuisance trips of breakers in light aircraft are

 the 60A b-lead breaker tied to a 60A alternator.

 

 Your off-hand comment about the intelligence of folks

 working in GA is uncalled for and yet another manifestation

 of your long and oft demonstrated history of belligerent,

 ill-informed, nay ignorant participation on this List.

 There are MANY folks within GA that would very much

 like to rectify the condition cited . . . but it's never

 bubbled to the top-ten-problems list with an airframe OEM and

 the FAA makes it insanely $difficult$ to make even the

 simplest changes. Hence, this marginal design has

 endured for decades more out of resignation to the

 authority of a higher power than of ignorance or apathy.

 

 

 > >In my humble opinion, ignoring a lot of experience and

 > >thoughtful reasoning suggesting that panel a mounted, b-lead

 > >breaker is not the best-we-know-how-to-do.

 > >Bob . . .

 >

 >What?

 >

 >Fuses are fine. Buth with (stock) internal regulation the CB is a good

 >reason to use a B-lead CB. Other engineers have worked on this

 >Bob. The pull-able CB for the B-lead is specified. It's irresponsible of

 >you to be so stubborn and opinionated, making ONE blanked edict

 >that one size fits all. Fuses are not a BE ALL solution for every

 >application. Follow the manufactures recommendation!

 

 This isn't a fuses/breakers discussion, it's

 an examination of the physics which govern assembly

 of some exceedingly simple ideas into recipes for

 success with an acknowledgment of hazards which

 should be considered as part of a thoughtful design.

 

 >

 >In my humble opinion, I disagree with Bob with my thoughtful reasoning

 >and facts. I don't care what you use but know why you are using it. I

 >don't believe you will have noise or won't be able to disconnect the

 >b-lead manually if you want to. When people talk 100's of volts & fire

 >they are exaggerating in non-scientific emotional arguments, not

 >engineering. Have Bob prove these are real problems. I could come

 >up with lots of NIT PICK reasons a fuse really is a poor choice.

 

 George, you have been politely requested to keep

 your comments on this topic to yourself . . . they've

 been read many times for years on this List and debunked

 as recorded and published at:

 

 http://www.aeroelectric.com/articles/gmcjetpilot.html

 

 http://aeroelectric.com/articles/The_Truth_about_Crowbar_OV_Protection.pdf

 

 You have designed nothing, fixed nothing, contributed

 nothing to the understanding of physics, serviced no

 customers, taught no classes, or offered a 100% satisfaction

 assured warranty for your products. Yet you persist

 in lurking at the edges of a sandbox not of your

 construction to throw rocks and mud while hiding behind

 a pseudonym decorated with much alphabet soup of

 self proclaimed titles/accolades. You claim superior

 engineering insight while never having demonstrated

 it with useful work-product.

 

 I've demonstrated/experienced/explained every assertion

 I've ever made based on my hands-on experiences with these

 systems since I did my first OV relay design for Cessna

 Aircraft in 1975. Your belittling diatribes and circular

 arguments contribute nothing to the advancement of

 our science, understanding or art and yet you deign to

 call me a liar. Your brand of 'science' is not welcome

 in this classroom. You sir are the secretive, fraudulent

 participant in these discussions and I will ask you

 politely for the third or forth time, please go away.

 

 Bob . . .

 

 (---------------------------------------)

 ( . . . a long habit of not thinking )

 ( a thing wrong, gives it a superficial )

 ( appearance of being right . . . )

 ( )

 ( -Thomas Paine 1776- )

 (---------------------------------------)

 

 

=====
	


 	  Quote: 	
		   

 

 


	


  [quote][b]

nuckolls.bob(at)cox.net
Guest

Posted: Wed Nov 21, 2007 8:47 pm Post subject: Pullable 60 Amp Breaker

At 07:43 PM 11/21/2007 -0600, you wrote:



 	  Quote: 	
		  



With several hundred, uh thousands (they become blurred and seemingly 

insignificant)  of flight hours I now attempt a life-long goal of building 

my own airplane.  My self-professed weakness is wiring, electronics and 

electricity in general.  Thus, my reason for joining this forum.  I read 

every post with an open mind and hopefully add to my limited understanding 

of the traveling electron.



In following this thread of "Pullable 60 Amp Breaker" I am reminded of 

something I learned a long time ago.  The only difference between a jet 

pilot and a jet engine is the fact that a jet engine stops whining when 

you shut it down.


	




   It is for folks such as yourself that at least

   some among us must go out of their way to protect

   the liberties of all against the attacks of a

   few. This is the simple-idea that defines

   honorable behavior. I (and I'm sure others)

   will continue to sift and refine the inventions

   to be formed from solid understanding of their

   component simple-ideas. You have come to the

   right place sir.



   Bob . . .

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