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#4063 - 09/09/01 01:42 PM AFCI breakers  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
I've been reading some of your older messages about provision of AFCIs. This is quite fascinating as we don't have anything like these breakers over here (not yet anyway!).

Does anyone know exactly how these devices work?


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#4064 - 09/09/01 08:29 PM Re: AFCI breakers  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
http://www.zlan.com/arc.htm

Paul;
they sense an arc of (i believe) 75W or more

.......have you ever heard the expression 'tail waggin' the dog'???
[Linked Image]

[This message has been edited by sparky (edited 09-09-2001).]


#4065 - 09/10/01 08:17 AM Re: AFCI breakers  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Thanks for the link. I figured they'd obviously have to be more complex than the standard thermal/magnetic or even amplified GFI types.

The only way I can see for them to work is for the circuitry to look for short pulses of increased current but not trip on longer pulses. I can see how such a circuit could be developed with simple op-amps etc. in integrated form, though I wouldn't be surprised if they actually use a micro-controller to analyze the current pulses.

I just wondered if any more technical details on the actual arrangement were available.

Does the AFI rely on the control circuitry to trip on normal overcurrent, or does it incorporate a normal thermal/magnetic trip as a backup?

Quote
Originally posted by sparky:

.......have you ever heard the expression 'tail waggin' the dog'???


Most definitely!


#4066 - 09/10/01 06:14 PM Re: AFCI breakers  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
http://www.zlan.com/afci_c4.htm

Paul,
i could'nt really answer any of your Q's , this (check pix in link) is definitly not my forte' .

i'd like to know how to detect a bad AFCI


#4067 - 09/10/01 08:09 PM Re: AFCI breakers  
sparky66wv  Offline
Member
Joined: Nov 2000
Posts: 2,236
West Virginia
Steve,

No "test button" as per GFCI?

I've yet to get a close look at one of these buggers...

Guess the "pair of wires and a really steady hand" won't do it...

Great Q... Just how do we test them?

[Linked Image]

I suppose one could run a spot (read arc) light on an AFCI circuit (If you could find one that runs on 120V 20A) and provide a known safe long-lasting arc...

[This message has been edited by sparky66wv (edited 09-10-2001).]


-Virgil
Residential/Commercial Inspector
5 Star Inspections
Member IAEI

#4068 - 09/11/01 05:27 AM Re: AFCI breakers  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
Virgil;
yes there's a test button on the breaker itself, just like a GFI. I just haven't found a tester to plug in thoughout the circuit like the one's used for receptacles with the GFI tester.
where would i get a calculated arc of say, 76watts's [Linked Image]


#4069 - 09/11/01 04:53 PM Re: AFCI breakers  
nesparky  Offline
Member
Joined: Jun 2001
Posts: 642
omaha,ne
Don't worry since this will be a problem sure the mahufacturers who got the code comitte to cram them down our throuts will soon have a expensive tester for us to buy.


ed

#4070 - 09/11/01 06:55 PM Re: AFCI breakers  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Quote
Originally posted by sparky66wv:

I've yet to get a close look at one of these buggers.


Now there's another word that has a somewhat different meaning on this side of the Atlantic!


#4071 - 09/11/01 07:01 PM Re: AFCI breakers  
pauluk  Offline
Member
Joined: Aug 2001
Posts: 7,520
Norfolk, England
Quote
Originally posted by sparky:
http://www.zlan.com/afci_c4.htm
Paul,
i could'nt really answer any of your Q's , this (check pix in link) is definitly not my forte' .
i'd like to know how to detect a bad AFCI


Thanks for that. The diagrams & notes on that site are very helpful. Looks as though as I was right about the microprocessor analyzing the current.

Did you follow the links there to the pages about testing an AFCI?

They seem to be using another micro-driven test unit which stores typical arc waveforms and then re-generates them to test the breaker, except it's done via the non-shunted neutral line only in order to keep the current down.


#4072 - 09/11/01 08:07 PM Re: AFCI breakers  
sparky  Offline
Member
Joined: Oct 2000
Posts: 5,311
http://www.zlan.com/testing/testing3.htm

well it certainly looks $$$$
[Linked Image]


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