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inline ac polarity checker

stupidinventer

Mar 26, 2014
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Mar 26, 2014
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I’m looking to find a way to check polarity inline. What I’m doing is I have people build power supply’s for me I have made a tester for them but I cant figure out how to have it check the ac polarity inline. the power supply’s do not have a ground if that helps. I have been experimenting with already available testers u can buy at home depot but they wont test beyond were they are plugged in witch defeats the purpose. Any ideas would help immensely. [email removed]
 
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davenn

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Sep 5, 2009
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hi there
welcome to the forums :)

you know you cannot check the polarity of an AC mains circuit it changes back and forward 50/60 times a second

so what are you really trying to achieve ?

cheers
Dave
 

KMoffett

Jan 21, 2009
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I think that the OP is referring to "outlet checkers". Which has nothing to do with the wiring of the AC side of power supply. For that, (s)he would have to compare the continuity of the AC wiring of the power supply to the design schematic. With no ground to reference, there is no real difference with which side of the AC line goes to the internal circuit.

We had a sales person sneak a prototype device into one our hospital ORs. It set off the power isolation monitors. I went to bench test it and got knocked across the room. Had one hand grounded (not realizing it) and touched the metal case with the other. The person that assembled it has reversed the hot and ground wires inside the case. :eek:

Ken
 

kpatz

Feb 24, 2014
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You say the supplies aren't grounded, I assume that means they have a 2 prong plug? Is the plug polarized (fits only one way in the socket)?

If they are, and you can tell by looking at the board which is supposed to be "hot" and which is supposed to be "neutral", you can use a multimeter to test the continuity, to ensure that the neutral connection on the board is connected to the wider prong on the plug. Obviously do this with it unplugged, and try not to touch any capacitors on the board as they can carry a high voltage.

If the plug isn't polarized, this means the supply is (hopefully) properly insulated and the output is properly isolated, so it won't matter which way it's plugged in.
 

davenn

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Sep 5, 2009
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I think that the OP is referring to "outlet checkers".

yup assumed that, but wanted the poster to make clear his intensions ;)

Dave
 
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