CAFI and GFCI Breakers

[Kiril]

What do you mean by?

Perhaps this will shed some light on what I'm referring to.

Arc Fault Detection Through Model Reference Estimation

Why would you want to install Ground Fault Circuit Interrupters on a home automation for in the first place?

I'm not to the housing. The UPB switches and some receptacles are part of the "home automation" system.

Simply Automated

If anyone has any experience with the above products, I would welcome any insights and opinions.

 

[JWelectric]

I think that there is a big difference in the arc fault device in a home and one in an aircraft.

 

[Sponsor]

 

[Kiril]

I think that there is a big difference in the arc fault device in a home and one in an aircraft.

I don't think you read the paper, and even if it was about aircraft systems, I believe electricity operates the same in an aircraft as it does in a house.

See section 4.0

ARC RECOGNITION IN AN AC NETWORK

In order to validate the arc recognition approach,
experiments were carried out using a published standard
for arc recognition in 60 Hz alternating current systems,
U.L. 1699 [7]. In our experiments, current data was
collected using a 1000:1 current sense transformer,
model number CT-000, manufactured by Coilws.com,
Inc. Samples of current information were acquired at 50
KHz using a 12 bit A/D converter. Two benchmark
cases were developed that correspond to what are
generally very difficult cases to analyze for a fault. The
first such case is an 800 watt dimmer circuit that is
highly nonlinear and that exhibits many of the behaviors
typical of arcing but that is not a fault load and should
not be identified as such. The second case is a low
level carbonized path fault which is masked by a
legitimate load. A successful arc detection procedure
should always recognize the latter situation as a fault
and should never recognize the former.​

Anyhow, I am just trying to understand this better so I know what performance I can to expect from the equipment I put into my house. I discussed the matter with my better half and we decided that the best approach would be to use CAFI in place of the required AFCI, and use GFCI receptacles instead of breakers for personnel protection.

 

[Speedy Petey]

Kiril, are you an engineer, or maybe IBM?

 

[Mikept]

I have a question for the EE's here who understand these things. Would a CAFI prevent me from using my crowd pleasing 60hz 15kv30ma NeonSignTransformer based 3' high Jacobs Ladder?

 

[Mikey]

My first reaction would be - no, since the arc is downstream from the transformer. However, CAFIs weren't part of my EE curriculum . I've wondered about the arcs produced by the motor in my Bosch hammer-drill, though.

Kiril - I think GFCI, AFCI, and CAFI can be summarized as:

GFCI - intended to protect personnel by tripping on current flow of 5-6ma out of the circuit - presumed to be through a person to ground.
AFCI - intended to protect property by tripping when a series arc is detected - presumed to be a fire-starting event. (And, indirectly, to protect personnel from the ensuing CO and fire - they were first required in bedrooms.)
CAFI - intended to protect propery by tripping as an AFCI does, but also when a parallel arc (i.e., to ground) of 5A is detected. Both events are potential firestarters, but if the parallel fault is to ground via a person, it's a fatal current.

Note that none of these devices provides surge protection for attached devices. In a perfect world, a single device would provide protection from every imaginable fault, and would be inexpensive, but this is an imperfect world. The paper you cited is an interesting way to go about attacking the technical problem; I doubt we'll ever consider it inexpensive, but if it's attached to an airplane it doesn't have to be.

Probably the best way to get all protections now is lightning protection, a whole-house surge protector, CAFIs at the panel, GFCI receptacles, and purpose-built surge protection at the device. I've got 3 out of 4 (no CAFIs yet) and haven't fried anything yet while living in the most lightning-prone area of the US. (see http://www.lightningsafety.noaa.gov/lightning_map.htm)

Mike (EE, A&P, ex-IBM, fwiw)

 

[JWelectric]

Kiril, are you an engineer, or maybe IBM?

Petey, Take a few minutes and read that paper and have a few laughs as I did.

Arc Fault in the home will never see anything used in the testing process outlined in that paper.

Using a sampling rate of 50 KHz,

Someone somewhere must have a lose cork to think that the average home is going to have anything close to this with another load in parallel.

Then in their test they set controls to keep the arc at a predetermined level. When we have an arc fault is a system installed in a house I suppose that the gremlins come around and install equipment to keep the arc to a level and frequency that fools the arc fault device.

The only thing that I gathered from reading that link is that in a lab I can get just about any result my heart desires to prove just about anything I decide I want to prove.

 

[Mikept]

No the frequency of the test was 60hz, they didnt change that to get a good arc. Their device took current mesurments (samples) 50k times a second.