Products > Test Equipment
Brymen BM789
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2N3055:

--- Quote from: AVGresponding on September 25, 2021, 07:24:07 am ---
--- Quote from: joeqsmith on September 24, 2021, 10:07:06 pm ---I think it was an American who asked.

Not too surprised by by people getting a poke from their appliances.  I was surprised they were concerned about an arc flash.   I wonder if there's a special group that consider ANY spark an arc flash event.  Maybe the same group that always discusses safety here?  That would explain a lot.   

That can't be it because it seems many are not from the United States.

--- End quote ---

"arc fault protection" is the latest buzz-phrase in electrical installation here. Lots of profit to be made implementing the new regs, which is a good thing, right?   :popcorn:

--- End quote ---

There is a lot of confusion because there is a failure mode where in residential installations, sometimes bad connections cause local sparking and contact resistance overheating of connections, that can damage insulation to the point of it itself becoming conductive and starts heating by itself and can create fires.. They realized that this bad contact sparking could be detected by looking into current spectrum etc...

Some of that detection technology came from arch flash fault protection tech (current signature analysis), so marketing jumped at opportunity and used all the drama and buzzwords to make appear that is some sort of "distant cousin" of arc flash accidents.. And you should be afraid, very afraid.. Jerks... They call it "arc protection", not "arc flash fault protection" so technically they didn't say it is the same..

Slow smoldering of insulation and arc flash accidents shouldn't be confused...

Arc flash accidents cannot happen if there is not enough energy.
Non professional shouldn't work on anything where arc flash accident can happen.
And probably won't have access to anything where it can happen.

OTOH, people nowadays have large machinery in their garages, and it is tempting to try to repair failed VFD or welding inverter by yourself. Some of these can have serious DC capacitor bank, that can hurt you. Those can seriously hurt your face, hands, eyes and hearing...
When shorted, compared to real arc flash accident, they are mere large firecrackers compared to the block of C4 .
But you can get seriously hurt by firecracker if you put it next to your face or hold it in a closed hand.


 
bdunham7:

--- Quote from: AVGresponding on September 25, 2021, 07:24:07 am ---"arc fault protection" is the latest buzz-phrase in electrical installation here. Lots of profit to be made implementing the new regs, which is a good thing, right?   :popcorn:

--- End quote ---

I just had a fire that did thousands of dollars of damage that was due to a defective device arcing internally.  I have AFCI breakers on certain circuits, but this was a 240VAC circuit for the swimming pool, so GFCI not AFCI is what is installed.  AFCI might just have prevented that fire. 
joeqsmith:

--- Quote from: 2N3055 on September 25, 2021, 08:25:39 am ---There is a lot of confusion because there is a failure mode where in residential installations, sometimes bad connections cause local sparking and contact resistance overheating of connections, that can damage insulation to the point of it itself becoming conductive and starts heating by itself and can create fires.. They realized that this bad contact sparking could be detected by looking into current spectrum etc...

Some of that detection technology came from arch flash fault protection tech (current signature analysis), so marketing jumped at opportunity and used all the drama and buzzwords to make appear that is some sort of "distant cousin" of arc flash accidents.. And you should be afraid, very afraid.. Jerks... They call it "arc protection", not "arc flash fault protection" so technically they didn't say it is the same..

Slow smoldering of insulation and arc flash accidents shouldn't be confused...
...

--- End quote ---

I watch very few electronics channels and even less having to do with electrical circuits.  That said, I subscribed to John Ward's channel years ago and have watched several of his videos.   

He produced several on this subject.  I left him a comment after seeing one of his early ones and was glad to see him continue to provide more details about them.    I tried to procure that exact same part from Eaton but wasn't able to locate one in the USA. 






Neutrion:
One more question about the BM789 which annoys me a bit:
The treshold for continuity is between 100Ohm and 420Ohm.
First I am not sure what this intervall means. But more importantly, isn't 420Ohm too high for finding shorts? I got used to 10-20Ohm but this one beeps all the time. Now I see that the 869 has also 200Ohm treshold but they doubled that with the 789. So there must be some application for it... What is it? I can't think it is just accidentally so high.
(The continuity voltage is 2,3 Volts measured with a multimeter.)
bdunham7:

--- Quote from: Neutrion on September 25, 2021, 04:11:21 pm ---The treshold for continuity is between 100Ohm and 420Ohm.
What is it? I can't think it is just accidentally so high.

--- End quote ---

It might be that they use a low test current.  Unfortunately, continuity threshold is a spec that we will all never agree on, so the only solutions are to either live with what you get or find a meter that has selectable thresholds--which is pretty rare.
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