The following is not meant to be anything more than a sharing of my experiences in using my UT210e for doing DC current measurements with the clamping jaws. I am not planning of working through the theory, but if discussion wants to travel that path, I am all for it.
Most clamp meters can only do current measurements in the AC domain and some of those can be really cheap and even the cheap ones can give useful measurements if you keep within their limitations - notably frequency. DC current measurement is more challenging and requires something different to the simple loop antenna approach.
The UT210e is one of those meters that can do it, but there are a couple of tips I would like to offer that have come from my efforts to get consistent results using one of these.
First, my testing setup:
I have 2 LED strips salvaged from an old TV that are mounted under my desk. (These have been invaluable in locating things dropped on the floor.) Each has it's own wiring running back to a bench power supply. Here, I have separated the wires in order to have easy access for the clamp.
Once switched on to the 2A range, the
Select button is pressed once to switch the meter into DC mode.
Bring the clamp up NEXT TO the wiring you want to measure - in the position you will be using to perform the measurements (or as close as possible). Do NOT put any wires through the clamp jaws!
You will likely get a non-trivial reading: (I have had some instances where I get a reading of over 200mA.)
Keep the meter in that position and press the
Zero button
You will now have a reading that will be close to zero. If you are lucky, it will be zero.
It's important to keep the meter in the same orientation!! Here's what can happen with just changing the angle - and I've had variations of 30mA or more doing this ... and we haven't even tried taking a measurement yet!