AFCI test button

[K8MHZ]

As we all know, the only way to test both GFCI and AFCI devices is by using the test button.

Having knowledge of the internal workings of a GFCI, I can see how pressing the test button creates an electrical imbalance through a CT by partially bypassing it. The CT detects resultant current and the device is electrically activated. The test button function is pretty close duplicating to any real world possibilities that exist.

I haven't torn an AFCI apart. I want to know if pushing the button is just a mechanical activation, or does the button create a type of a spark that the internal components 'see' and the device electrically shuts down, as the above?

Or does it simply supply voltage to an IC that has one pin set to trip when it sees that voltage, and that pin has no other function?

Inquiring minds want to know.

Thanks

 

[hbiss]

Or does it simply supply voltage to an IC that has one pin set to trip when it sees that voltage, and that pin has no other function?

Going by the smoke and mirrors that these things are I think that would be an accurate assumption. :roll:

-Hal

 

[kwired]

If you don't work for the design team of one of the AFCI manufacturers you don't have proper security clearance to see that information.

It is better protected then a lot of National Security information is.

Nothing will stop you from taking one apart, but there aren't that many out there with the interest in doing so that will understand what they are looking at.

 

[GoldDigger]

The difficult part is figuring out the contents of the program memory by looking at the outside of the chip.

 

[JFletcher]

As we all know, the only way to test both GFCI and AFCI devices is by using the test button.

Yes, because duplicating a series fault is not a way to test an AFCI (or, imo, the AFCI fails the test).

 

[mgookin]

The difficult part is figuring out the contents of the program memory by looking at the outside of the chip.

+1

 

[bphgravity]

Section 15.1 of the UL 1699 Standard for AFCIs:

15.1 An AFCI shall be provided with a test circuit that simulates an arc such that the arc detection circuit
or software is caused to detect the simulated arc.[

 

[Little Bill]

Section 15.1 of the UL 1699 Standard for AFCIs:

How does UL (or anyone) tell if a simulated arc is actually produced or just a "snake oil" button to kill the circuit when it's pressed?

 

[mbrooke]

How does UL (or anyone) tell if a simulated arc is actually produced or just a "snake oil" button to kill the circuit when it's pressed?

Even then, the arc that the AFCI might be simulating might not be what arcing looks like in the real world to begin with. Point being the AFCI in that guys video could certainly produce a glove upon hitting test for the signature analysis at hand within the AFCI, however glove or hand none reflect the real world.

 

[ceknight]

Section 15.1 of the UL 1699 Standard for AFCIs:

:thumbsup:

Just a suggestion, but you might get some insight into each mfr's test button functions by looking up their patents. The only ones I'm (barely) familiar with are Pass and Seymour's, only because a friend of mine (Bruce Macbeth) did much of their AFCI developing and inventing way back when.

If you look up the patent info for the P&S combo GFCI/AFCI test button, for instance, you'll find this abstract: "A combination AFCI/GFCI includes a single test button which when pushed, tests both the arc fault and ground fault detection circuitry and the circuit interrupter. Closing the test button causes a simulated ground fault and enables a signal steering circuit. The steering circuit redirects the ground fault detector output to an arc fault simulator circuit which produces a simulated arcing pulses that are coupled, preferably by way of an extra winding, to an arc fault sensor transformer. The arc fault detector senses the arc fault simulator pulses coupled to the sensor transformer and, if everything is operating normally, triggers a switching device such as an SCR which activities a circuit interrupter. In this way, both the ground fault circuit interrupter and arc fault circuit interrupter functions are tested simultaneously, and the test is initiated by a single test button. When the circuit interrupter is not in the test mode, the steering circuitry is disabled and either a ground fault or an arc fault or both will independently activate the switching device and the circuit interrupter."

Of course, patent info is no guarantee that they produced it that way, there could just be a little vial of snake oil in there instead.

 

[mgookin]

How does UL (or anyone) tell if a simulated arc is actually produced or just a "snake oil" button to kill the circuit when it's pressed?

When you get a product listed, your trade secrets remain just that.
You have to give them enough information for them to be able to be assured of compliance, but they don't necessarily release that information in the listing.