On 11/05/2019 14:33, Commander Kinsey wrote:
I got hold of a second hand one of these:
https://www.torontosurplus.com/rs-co...lampmeter.html

A HEME 100 clamp meter.
I can't find specs for it online, only a HEME 1010.
I've tried reading a few currents with it (using a brand new battery in
it), and it seems to underread a fair bit on DC (0.56A instead of 0.62A)
and AC (7.5A instead of 8.5A).* It's also susceptible to wires near it -
for example if you put the live inside the clamp but the neutral is an
inch or so from the outside of the clamp, it reads a bit of that too and
gives a higher reading.* Are these things supposed to be accurate?* Can
I adjust it?

How are you measuring the reference currents of 0.62A and 8.5A?

Using the specification of the HEME 1010

You are on the 400Amp range with a resolution of 0.1A
The accuracy is +/-5 digits (+/- 0.5 Amps) plus 1.3% of reading (0.1A)
so the reading is 6A +/-0.6A

If you are using a multimeter as the comparison it may be equally
inaccurate, especially if the internal battery is failing. Often a
failing battery in a multimeter gives high readings.


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