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KamW
Joined: 16 Jul 2001
Posts: 68
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 16 Oct 2004 18:34 How to check if isolated circuit is not shorted |
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Hi
I have two isolated circuits. I am looking for idea, of how could I check if there is no short between them.
Of course it is easy with external ohmometer, but in fact I have to ask uC in one circiut if there is no short with the second one. Both circuts are optoisolated.
Best regards
KamW
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prinsloo
Joined: 19 Sep 2004
Posts: 94
Helped: 1
Location: Bethlehem RSA
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| 16 Oct 2004 18:50 How to check if isolated circuit is not shorted |
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| Ohm meter is the prefered way,you'll have to take uot all ic's and follow the schematics or take out the ic's and switch circuit on. Good luck
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KamW
Joined: 16 Jul 2001
Posts: 68
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| 16 Oct 2004 18:56 Re: How to check if isolated circuit is not shorted |
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Hi prinsloo
ohm meter it was kind of joke- in fact I have to check in real time if there is short circuit. One circuit has to check if it is shorted with the second, and there still should be optoisolated barier between circuits.
Any idea?
KamW
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nicleo
Joined: 06 Sep 2004
Posts: 717
Helped: 60
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| 17 Oct 2004 3:11 How to check if isolated circuit is not shorted |
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| Is the optocouler (I assume it's optocoupler as you mentioned both circuits are optoisolated) the only device that connect both circuits?
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KamW
Joined: 16 Jul 2001
Posts: 68
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| 17 Oct 2004 9:11 Re: How to check if isolated circuit is not shorted |
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Yes exactly. And I have to check if it really is the only one !!
Question is very simple, but solution ......
regards
KamW
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nicleo
Joined: 06 Sep 2004
Posts: 717
Helped: 60
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| 17 Oct 2004 14:13 How to check if isolated circuit is not shorted |
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| Interesting question ... do you have any idea what are the possible causes that will result in short-circuit between circuit1 and circuit2 ?
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KamW
Joined: 16 Jul 2001
Posts: 68
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| 17 Oct 2004 20:40 Re: How to check if isolated circuit is not shorted |
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In meter with two independent measuring path it is extremally easy. A lot of connections will be outside of the box ...
Problem is that the results of measuremens are false while there is short circuit between meters
regards
KamW
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House_Cat
Joined: 21 Feb 2002
Posts: 1356
Helped: 275
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| 18 Oct 2004 7:03 Re: How to check if isolated circuit is not shorted |
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The only way to detect whether the two circuits are "shorted" together from inside the circuits is if some current flows between the two. In order for that to be true, there has to be a return path for the current between the two in addition to the "short".
If the two circuits do not share anything in common, and are totally opto-isolated, there is no way to detect a single "shorted" point between the two from within either one.
An analogy would be to lock yourself in a windowless room and try to detect when someone is touching the wall on the outside of the house - you can't do it without some information from outside the room.
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KamW
Joined: 16 Jul 2001
Posts: 68
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| 18 Oct 2004 9:36 Re: How to check if isolated circuit is not shorted |
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| There is no question that there should be any connection between citrcuits. I think a few Mohms would be enought. But in my oppinion the problem to avoid destruction of one of circuit while there are high difference in potentials between them. Am I right?
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nicleo
Joined: 06 Sep 2004
Posts: 717
Helped: 60
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| 18 Oct 2004 10:10 How to check if isolated circuit is not shorted |
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| Are both circuits identical?
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KamW
Joined: 16 Jul 2001
Posts: 68
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| 18 Oct 2004 14:03 Re: How to check if isolated circuit is not shorted |
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| Of course they are not identical. One is uC with meter, and the second is just meter.
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