Products > Test Equipment
Non-Contact voltage sensing (NCV) "pen" or similar for DC?
AndyC_772:
--- Quote from: M0HZH on April 13, 2023, 02:23:16 pm ---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.
--- End quote ---
My interest in this topic is for an application that's not safety critical (we know the cable is live, always) - but we'd like to measure the voltage with some quantifiable degree of accuracy. A simple 'voltage / no voltage' isn't useful.
I can't think how it might work, though I know there are instruments used in ESD control that can measure the electrostatic potential at a point with respect to ground.
Presumably whatever technique they use wouldn't be useful here, since it's perfectly possible to have an insulated cable with a conductor at 400V on the inside, but a surface charge giving multiple kV on the outside.
Piercing the insulation with a sharp probe isn't an option, sadly.
joeqsmith:
https://youtu.be/n7z9DjCaxD8?t=201
ckambiselis:
While this seems a good option, would an electrostatic fieldmeter be able to measure at these lower voltages under 1kv? The value doesn't need to be accurate anyway.
Kleinstein:
--- Quote from: ckambiselis on April 21, 2023, 05:20:52 am ---While this seems a good option, would an electrostatic fieldmeter be able to measure at these lower voltages under 1kv? The value doesn't need to be accurate anyway.
--- End quote ---
It depends of the distance ( capacitance) one can have. The fieldmeter is sensitive to voltage divided by distance. In a controlled evironment, a Kelvin probe can get to the 10 mV range.
There are a few describtions on field-mills.
A principle problem is that it does not take much (e.g. charges trapped at the surface of insulators) to effect the electrostatic field. For an AC detection there is also often quite some background main hum around.
ckambiselis:
Well the devices are unpowered and the closest powered device is the motor moving the line, under it, behind around 4mm of grounded aluminum. It is possible to stick a non contact insulated prob in the device to "search around" for possible voltages, to make it easier for the meter to detect the voltage.
Oscar
Navigation
[0] Message Index
[*] Previous page
Go to full version