New clamp meter uni-t ut210e - readings

[mike_mike]

Hi! I have a Uni-t UT210E clamp meter.
I get the following AC current readings on the display, first when the wire is on the upper part of the clamp, and the second when the wire is on the lower part of the clamp.
It is normal to get 2 different readings ?

LE: I am powering a few halogen lamps, from a 12Vac power transformer. the meter is at about 10cm close to the transformer. Even if I place the meter to a higher distance from the transformer, the readings are the same.

[mikerj]

Yes pretty normal, the magnetic circuit in these seems to be a bit "leaky" so moving the wire around can slightly different results.  When using a clamp meter, after placing the jaws around the wire zero the meter and don't move the wire whilst taking measurements.

[radiolistener]

I get the following AC current readings on the display, first when the wire is on the upper part of the clamp, and the second when the wire is on the lower part of the clamp.
It is normal to get 2 different readings ?

Just tested for AC current, my UT210E measurement doesn't depends on wire position (about 0.001 Amp change or no change at all).

But if you're using DC measurement mode, UT210E is very sensitive to the environment magnetic field, so it can change for a little if you move or rotate clamp meter. Use ZERO button in DC mode to eliminate offset. And measure current in the same position as you pressed ZERO button in order to avoid offset due to environment magnetic fields.

[Doctorandus_P]

I would expect some difference but 15A and 16A are reasonable currents and about 12% apart.

Recently I saw an extensive teardown and adjustment procedure (on youtube) for the thing. It has 2 Hall sensors (one on each side of the jaw) in a bridge configuration and a few pots to balance the bridge.

[Trader]

Hi! I have a Uni-t UT210E clamp meter.
I get the following AC current readings on the display, first when the wire is on the upper part of the clamp, and the second when the wire is on the lower part of the clamp.
It is normal to get 2 different readings ?

LE: I am powering a few halogen lamps, from a 12Vac power transformer. the meter is at about 10cm close to the transformer. Even if I place the meter to a higher distance from the transformer, the readings are the same.

https://www.fluke-direct.com/pdfs/cache/www.fluke-direct.com/i2500-10/datasheet/i2500-10-datasheet.pdf

[theHWcave]

@Trader, that's  really interesting but more for other meters. The UT210E uses hall-effect sensors which work on a different principle than the Fluke sensor which looks like a Rogowski coil which are know to be sensitive to were the wire is position. That said, it strikes me that all the pictures in the datasheet have the loop hanging around the wires which is convenient but the worst position for accuracy according to the very same datasheet.  Moreover they are shown surrounding several cables at one which is normally a no-no with clamp meters. Maybe that is useful to get an idea if the currents are not balanced? It looks very odd.

@mike_mike: Check that the clamp is really closed properly. The ends need to be in contact across the whole area.  In the UT210E the mechanics of clamp are really not very strong despite looking fairly robust. I had to glue mine already.  The proper position for the wire is actually marked on the clamp with two little triangles on either side. Its much closer to the hinge than to the opening. The UT210E has only hall-effect sensors, and no current transformer, so the hall effect sensors are in use even for AC.The only difference is that for AC current, you don't need to zero the meter because the "DC" part is cancelled out. However, repeated measurements of strong AC currents can leave your meter magnetised just as happens with DC currents. So its a good idea to occasionally de-magnetize the clamp with a degaussing coil  (an AC field that slowly decays to zero over a few seconds) . I use one of the cheap chinese de-magnitizing units for that which is basically a mains transformer with only a primary and the iron core cut open. I added a PTC to get the automatically decaying field instead of having to slowly move the meter away from the running de-magnetiser which also works...

[Doctorandus_P]

I agree with the unfortunate fact that the mechanical part of the clamp is not very robust. It's the biggest disadvantage by far for this very nice clamp meter.

As I already wrote before, a 12% deviation is quite big. Bigger then it should be.
Later you added you had to repair the hinge by gluing it, and this may be the cause of the deviation.
This meter has two hall sensors, one on each side where the clamp halves meet, and the breaking and glueing is likely to have some effect on the distance between these halves and you may have to re-calibrate how the signals from these hall sensors are added.

[mike_mike]

I calibrated the clamp meter (by pressing the blue and yellow buttons at the same time and simultaneous rotating the knob to resistance, diode and capacitance measure) and now It mesures 10.16 Aac in the center of the clamp, 10.5 Aac in the upper side of the clamp and in the lower side of the clamp 9.95A.
A standard multimeter set to 20Aac measures 9.90Aac.

In the manual it shows +-(2.5%+8) accuracy on the 20Aac scale.

It is still bad ?

[Vovk_Z]

It is still bad ?

Very fine, I think. I doubt it can be better.

[mike_mike]

Finally, I returned the clamp meter to the shop, because it was working incorrectly.
I bought another model (UT203R) and this model seems to work better than the previous one.