Products > Test Equipment
Non-Contact voltage sensing (NCV) "pen" or similar for DC?
ckambiselis:
Hi,
I have been trying to find a tool to detect DC voltage at the 100-500V range without having to make contact with the circuit, but the only thing I can find is from an Australian company named Modiewark, which makes one for the rescue services, but the thing is massive for easier gripping and the price is over the roof.
The idea is to use it at a production line after safety testing the equipment which also powers up the device, there are a few DC capacitors that are still holding charge for a few minutes after the test, and we would like to make sure they are empty before the next guy starts handling the device, because of the mechanical design of the device, probing the circuit is really difficult, having to put your hands inside the device and possibly getting zapped.
I understand that technically since the current flowing is really small it is almost impossible to make a non-contact measurement, but maybe there is something I'm missing, any suggestions are appreciated.
Thanks
Oscar
AndyC_772:
I'd be interested in this too. Not sure what the underlying physical detection mechanism could be, though.
M0HZH:
The company I work for makes electrical test equipment (including NCVs) and I can tell you two things:
1. Non-contact detectors should NEVER be used for safety purposes.
2. As far as we know, there's no method to RELIABLY detect DC without contact. The electroscope principle wouldn't work reliably enough for safety products. R&D is looking into it, I'll post here if they come back.
As a side note, I would add a built-in bleed resistor, high-voltage capacitors should have one anyway.
ckambiselis:
The device does have bleed resistors, in about 2 minutes they should be empty, but they are just not fast enough for the production line, and making a change would cost a pretty penny, also not sure if they might effect the circuit in an undesirable way.
Would be interested in what your team comes up with!
Oscar
AVGresponding:
Perhaps you should consider adding in a manual switch with lower value resistor, to discharge them faster.
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