Matronics Email Lists Forum Index Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
 
 Get Email Distribution Too!Get Email Distribution Too!    FAQFAQ   SearchSearch   MemberlistMemberlist   UsergroupsUsergroups   RegisterRegister 
 ProfileProfile   Log in to check your private messagesLog in to check your private messages   Log inLog in 

Why CB on regulator field supply?

 
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List
View previous topic :: View next topic  
Author Message
Voyager



Joined: 30 Jun 2020
Posts: 29

PostPosted: Sun Jan 16, 2022 1:25 pm    Post subject: Why CB on regulator field supply? Reply with quote

I have two questions I have yet to find an answer to either through searches here or in the AeroElectric Connection.

1. I follow Bob’s logic on using fuses rather than breakers and am planning that for my RANS S-21. However, his one exception seems to be on the supply for the regulator (alternator field). I am assuming a CB is specified here either to make testing the OC crowbar easier as the test is then nondestructive or because of the time to trip characteristic of a CB compared to a fuse. Can someone enlighten me as to the reason?

2. Peripherally related is the question as to why the FAA recommends higher rated CBs than fuses on many conductor sizes in table 11-3 in AC43.13-1B? Anyone explain that?

I assume both of those are explained somewhere, but I’ve yet to stumble on the explanations.

Thanks,
Matt


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
View user's profile Send private message
Ceengland



Joined: 11 Oct 2020
Posts: 252
Location: MS

PostPosted: Sun Jan 16, 2022 3:11 pm    Post subject: Why CB on regulator field supply? Reply with quote

On Sun, Jan 16, 2022 at 3:31 PM Voyager <m.whiting(at)frontier.com (m.whiting(at)frontier.com)> wrote:

Quote:
--> AeroElectric-List message posted by: "Voyager" <m.whiting(at)frontier.com (m.whiting(at)frontier.com)>

I have two questions I have yet to find an answer to either through searches here or in the AeroElectric Connection.

1. I follow Bob’s logic on using fuses rather than breakers and am planning that for my RANS S-21.  However, his one exception seems to be on the supply for the regulator (alternator field).  I am assuming a CB is specified here either to make testing the OC crowbar easier as the test is then nondestructive or because of the time to trip characteristic of a CB compared to a fuse.  Can someone enlighten me as to the reason?

2. Peripherally related is the question as to why the FAA recommends higher rated CBs than fuses on many conductor sizes in table 11-3 in AC43.13-1B?  Anyone explain that?

I assume both of those are explained somewhere, but I’ve yet to stumble on the explanations.

Thanks,
Matt

I'd have to wonder if the AC43 table issue is tied to the 'conditions':
 
[img]cid:ii_kyhv81nr0[/img]

Wild guess, but perhaps the fuse milspec is for some slow-blow fuse. A 'generic' breaker will typically open much slower than a 'generic' fuse. (Note the quotes....)
My understanding is that the roots of using a pullable breaker for the field are (at least) two-fold: It gives the pilot a way to manually disable a problem alternator, and it allows recovering from a 'nuisance trip' for instance, a momentary 'spike' in voltage due to a load dump may cause the OV protection to trip. A breaker gives you a chance to be sure that the OV issue is real, and not a nuisance trip.
Charlie


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List



image.png
 Description:
 Filesize:  12.2 KB
 Viewed:  929 Time(s)

image.png



_________________
Charlie
Back to top
View user's profile Send private message
Voyager



Joined: 30 Jun 2020
Posts: 29

PostPosted: Wed Jan 19, 2022 6:36 am    Post subject: Re: Why CB on regulator field supply? Reply with quote

Ceengland wrote:
On Sun, Jan 16, 2022 at 3:31 PM Voyager <m> wrote:

Quote:
--> AeroElectric-List message posted by: "Voyager" <m>

I have two questions I have yet to find an answer to either through searches here or in the AeroElectric Connection.

1. I follow Bob’s logic on using fuses rather than breakers and am planning that for my RANS S-21.  However, his one exception seems to be on the supply for the regulator (alternator field).  I am assuming a CB is specified here either to make testing the OC crowbar easier as the test is then nondestructive or because of the time to trip characteristic of a CB compared to a fuse.  Can someone enlighten me as to the reason?

2. Peripherally related is the question as to why the FAA recommends higher rated CBs than fuses on many conductor sizes in table 11-3 in AC43.13-1B?  Anyone explain that?

I assume both of those are explained somewhere, but I’ve yet to stumble on the explanations.

Thanks,
Matt

I'd have to wonder if the AC43 table issue is tied to the 'conditions':
 
[img]cid:ii_kyhv81nr0[/img]

Wild guess, but perhaps the fuse milspec is for some slow-blow fuse. A 'generic' breaker will typically open much slower than a 'generic' fuse. (Note the quotes....)
My understanding is that the roots of using a pullable breaker for the field are (at least) two-fold: It gives the pilot a way to manually disable a problem alternator, and it allows recovering from a 'nuisance trip' for instance, a momentary 'spike' in voltage due to a load dump may cause the OV protection to trip. A breaker gives you a chance to be sure that the OV issue is real, and not a nuisance trip.
Charlie


The characteristics of fuses vs. CB and nuisance trips were my guesses also, but I was hoping someone had more than a guess. Since the alternator supply is on a switch, I am not sure using a CB to manually turn off the alternator is needed as you can just turn off the alternator switch.


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
View user's profile Send private message
Ceengland



Joined: 11 Oct 2020
Posts: 252
Location: MS

PostPosted: Wed Jan 19, 2022 8:07 am    Post subject: Why CB on regulator field supply? Reply with quote

On Wed, Jan 19, 2022, 8:56 AM Voyager <m.whiting(at)frontier.com (m.whiting(at)frontier.com)> wrote:

Quote:
--> AeroElectric-List message posted by: "Voyager" <m.whiting(at)frontier.com (m.whiting(at)frontier.com)>


Ceengland wrote:
> On Sun, Jan 16, 2022 at 3:31 PM Voyager  wrote:
>
>
> > --> AeroElectric-List message posted by: "Voyager"
> > 
> >  I have two questions I have yet to find an answer to either through searches here or in the AeroElectric Connection.
> > 
> >  1. I follow Bob’s logic on using fuses rather than breakers and am planning that for my RANS S-21.  However, his one exception seems to be on the supply for the regulator (alternator field).  I am assuming a CB is specified here either to make testing the OC crowbar easier as the test is then nondestructive or because of the time to trip characteristic of a CB compared to a fuse.  Can someone enlighten me as to the reason?
> > 
> >  2. Peripherally related is the question as to why the FAA recommends higher rated CBs than fuses on many conductor sizes in table 11-3 in AC43.13-1B?  Anyone explain that?
> > 
> >  I assume both of those are explained somewhere, but I’ve yet to stumble on the explanations.
> > 
> >  Thanks,
> >  Matt
> > 
> > 
> I'd have to wonder if the AC43 table issue is tied to the 'conditions':
>  
> [img]cid:ii_kyhv81nr0[/img]
>
> Wild guess, but perhaps the fuse milspec is for some slow-blow fuse. A 'generic' breaker will typically open much slower than a 'generic' fuse. (Note the quotes....)
>
>
> My understanding is that the roots of using a pullable breaker for the field are (at least) two-fold: It gives the pilot a way to manually disable a problem alternator, and it allows recovering from a 'nuisance trip' for instance, a momentary 'spike' in voltage due to a load dump may cause the OV protection to trip. A breaker gives you a chance to be sure that the OV issue is real, and not a nuisance trip.
>
>
> Charlie


The characteristics of fuses vs. CB and nuisance trips were my guesses also, but I was hoping someone had more than a guess.  Since the alternator supply is on a switch, I am not sure using a CB to manually turn off the alternator is needed as you can just turn off the alternator switch.

The gotcha is the OV protection; if it 'nuisance trips, with a fuse there's no recovery. With a breaker, you can reset it. 


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Charlie
Back to top
View user's profile Send private message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Thu Jan 20, 2022 8:57 am    Post subject: Why CB on regulator field supply? Reply with quote

Quote:

The characteristics of fuses vs. CB and nuisance trips were my guesses also, but I was hoping someone had more than a guess. Since the alternator supply is on a switch, I am not sure using a CB to manually turn off the alternator is needed as you can just turn off the alternator switch.

ASSUMING elects to incorporate crowbar ov
protection in their project, then to mitigate
possible but RARE nuisance trips of the OV
system, a crew accessible circuit breaker is
the field supply protection of choice. In
the event of an OV trip event, the pilot has
an opportunity to reset the breaker ONE time
to confirm the existence of failure in the
alternator's regulator.

ADDITIONALLY, if one chooses to use a DPST
battery master switch, battery and alternator come
ON-OFF together, the a pullable field supply
breaker is handy for disabling the alternator
for battery only ground operations thus elininating
an energy wasting, full-field drain on the battery.

NOTE. When picking a breaker for upstream management
of field supply in the crowbar system, it is a
really good idea to pick a breaker that is (1)
qualified to function as designed after a substantial
number of hard-fault trips. (2) actuates really
fast under the typical 50 to 200A current pulse
that an OV event impresses on the device. This style of breaker
is highly recommended for this application:

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

This is one of many breakers NOT suited for service
upstream of a crowbar ov management device:

http://aeroelectric.com/Pictures/Breakers/Breaker_Failure_1a.jpg

Note also that all wound-field, alternator controllers
from B&C feature built-in crowbar ov management systems.
Incorporation of the recommended breaker applies to
these products. I've had a few readers over the years
who elected to protect their field supply with a fuse . . .
this is no more hazardous than a host of other
alternator failures . . . but pretty inconvenient
if that fuse resides in the recommended out-of-sight-
out-of-mind location in the airplane.




Bob . . .

Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
Steve Kelly



Joined: 08 Jul 2016
Posts: 18

PostPosted: Thu Jan 27, 2022 11:59 am    Post subject: Why CB on regulator field supply? Reply with quote

Bob,  This discussion poses a (probably dumb) question.  My system consists of a L40 alternator, LR3C-14 regulator and the 2 circuit breakers and lamp that come with B&C's installation kit.  Also have the standard split rocker switch for batt and alt.   The question is what is the appropriate action- in flight- to take if one of the breakers should pop or the light illuminates.   While I'm sure I could muddle through it, it would be nice to have a clear course of action.  If the 5A breaker pops does that mean there was an overvoltage situation.  If I reset it one time and it pops again, does that mean there is a problem with the regulator?  What about a warning lite and the breakers don't pop.  Does that mean that maybe the alternator is not producing power?
  Also, for me at least, being primarily VFR neither situation would be considered an emergency.
Thanks, Steve
On Thu, Jan 20, 2022 at 12:03 PM Robert L. Nuckolls, III <nuckolls.bob(at)aeroelectric.com (nuckolls.bob(at)aeroelectric.com)> wrote:

Quote:
Quote:

The characteristics of fuses vs. CB and nuisance trips were my guesses also, but I was hoping someone had more than a guess.  Since the alternator supply is on a switch, I am not sure using a CB to manually turn off the alternator is needed as you can just turn off the alternator switch.

   ASSUMING elects to incorporate crowbar ov
   protection in their project, then to mitigate
   possible but RARE nuisance trips of the OV
   system, a crew accessible circuit breaker is
   the field supply protection of choice. In
   the event of an OV trip event, the pilot has
   an opportunity to reset the breaker ONE time
   to confirm the existence of failure in the
   alternator's regulator.

   ADDITIONALLY, if one chooses to use a DPST
   battery master switch, battery and alternator come
   ON-OFF together, the a pullable field supply
   breaker is handy for disabling the alternator
   for battery only ground operations thus elininating
   an energy wasting, full-field drain on the battery.

   NOTE. When picking a breaker for upstream management
   of field supply in the crowbar system, it is a
   really good idea to pick a breaker that is (1)
   qualified to function as designed after a substantial
   number of hard-fault trips. (2) actuates really
   fast under the typical 50 to 200A current pulse
   that an OV event impresses on the device. This style of breaker
   is highly recommended for this application:

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

   This is one of many breakers NOT suited for service
   upstream of a crowbar ov management device:

http://aeroelectric.com/Pictures/Breakers/Breaker_Failure_1a.jpg

   Note also that all wound-field, alternator controllers
   from B&C feature built-in crowbar ov management systems.
   Incorporation of the recommended breaker applies to
   these products. I've had a few readers over the years
  who elected to protect their field supply with a fuse . . .
  this is no more hazardous than a host of other
   alternator failures . . . but pretty inconvenient
   if that fuse resides in the recommended out-of-sight-
   out-of-mind location in the airplane.

  


  Bob . . .

  Un impeachable logic: George Carlin asked, "If black boxes
  survive crashes, why don't they make the whole airplane
  out of that stuff?"



- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Steve
Back to top
View user's profile Send private message
user9253



Joined: 28 Mar 2008
Posts: 1770
Location: Riley TWP Michigan

PostPosted: Thu Jan 27, 2022 4:34 pm    Post subject: Re: Why CB on regulator field supply? Reply with quote

Whenever any circuit breaker pops, it is best to wait until safely on the ground before resetting or troubleshooting.
Circuit breakers can trip due to over current, or short circuits, or from loose wire terminals that make heat.
The best indicator of charging system failure is a voltmeter showing low voltage (less than 13.5VDC).


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Joe Gores
Back to top
View user's profile Send private message
nuckolls.bob(at)aeroelect
Guest





PostPosted: Fri Jan 28, 2022 9:55 pm    Post subject: Why CB on regulator field supply? Reply with quote

At 06:34 PM 1/27/2022, you wrote:
--> AeroElectric-List message posted by: "user9253" <fransew(at)gmail.com>

Whenever any circuit breaker pops, it is best to wait until safely on the ground before resetting or troubleshooting.

yeahhhh . . . mostly . . .

Circuit breakers can trip due to over current

(soft fault)

or short circuits

(hard fault)

or from loose wire terminals that make heat . .

(terminal on the breaker itself? probably
not . . . you'd have to conduct a LOT of
loose-joint, heat-energy into the breaker
to trip it's bi-metal current sense mechanism)

The best indicator of charging system failure is a voltmeter
showing low voltage (less than 13.5VDC).

Yes, but this discussion was about the SPECIAL
CASE for a DELIBERATE hard fault generated
by a crowbar ov management system. In this
case, it's possible that the ov trip was
a nuisance event so resetting this breaker
ONE time is called for. A short interval
re-trip is probable cause that the ov
condition is real.

The last generation of crowbar ov modules
were much more resistant to the dv/dt
transient . . . a number of my readers
have reported satisfactory operations with
just a fuse on the alternator field supply
feeder. If I resurrect this product, it will
probably be 100% immune to such stimuli.




Bob . . .

Un impeachable logic: George Carlin asked, "If black boxes
survive crashes, why don't they make the whole airplane
out of that stuff?"


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
user9253



Joined: 28 Mar 2008
Posts: 1770
Location: Riley TWP Michigan

PostPosted: Mon Jan 31, 2022 7:33 am    Post subject: Re: Why CB on regulator field supply? Reply with quote

Quote:
or from loose wire terminals that make heat . .

(terminal on the breaker itself? probably
not . . . you'd have to conduct a LOT of
loose-joint, heat-energy into the breaker
to trip it's bi-metal current sense mechanism)

I was speaking in general when I gave 3 causes for breakers tripping, not specifically the alternator field circuit.
I worked in an industrial electrical setting. On more than one occasion I found circuit breakers tripped due to heat caused by their screws being loose. Of course those circuit were probably carrying 15 amps or more. The whole electrical system in my RV-12 uses less than 15 amps. Smile
Speaking of loose screws, it seems that the vast majority of electrical problems are caused by loose connections.


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List

_________________
Joe Gores
Back to top
View user's profile Send private message
Voyager



Joined: 30 Jun 2020
Posts: 29

PostPosted: Sun Feb 13, 2022 5:58 am    Post subject: Re: Why CB on regulator field supply? Reply with quote

Bob, thanks for your explanation. What you said is what I was guessing, but it is good to hear it from the source. I plan to use a CB on the alternator and fuses everywhere else as I think the alternator field is the only circuit where you consistently use a CB in your architectural diagrams. Please let me know if there are other areas where you consider a CB a better solution.

Regards,
Matt


- The Matronics AeroElectric-List Email Forum -
 

Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:

http://www.matronics.com/Navigator?AeroElectric-List
Back to top
View user's profile Send private message
Display posts from previous:   
Post new topic   Reply to topic    Matronics Email Lists Forum Index -> AeroElectric-List All times are GMT - 8 Hours
Page 1 of 1

 
Jump to:  
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum


Powered by phpBB © 2001, 2005 phpBB Group