Good clamp meter for low DC currents

[ElectricPower]

Just wonder witch clamp meter i should buy if my main usage was to measure low DC currents in mA and uA with highest possible accuracy?

Is the EEVblog BM036 a good coice? Or can i buy something cheaper?

[wasedadoc]

Measuring such low dc currents with a clamp meter is prone to large errors.  The device is essentially measuring measurement magnetic field.  The wanted component is produced by the current you are trying to measure.  But other unwanted components come from the earth's magnetic field and other objects such as your screwdrivers, metal toolchest, vehicle engine and bodywork etc.  When set to measure dc current, clamp meters have a 'zero' button to null those out but the slightest movement of the meter changes those unwanted components and gives an error in your reading.

You can make the wanted field stronger if it is possible to have multiple turns of the wire passing through the clamp.  You then need to scale down the reading it gives you.

[DaneLaw]

What's your budget as it gets expensive fast if you want uA-clamp measurement ability?
uA in DC clamp regi?  gonna be a challenge to clean out for your "highest possible accuracy" and not drift.

I recall the UnitT 211B and the corresponding mocked-up Extech M63 can do uA on the clamp, but usually only in AC where they can muster 0.1mA resolution
An overall decent cheap AC&DC clamp meter for milliamp is the old UT210E, though not sure what they are going for here in late 2023 or if there are better alternatives for the price, as the UT210E got quite a few years/decade under its belly.. - many alternative models will nowadays do DC 1mA clamp measurement and quite a bit cheaper with dual display (freq) and higher native display count.

Previously the UT210E was around 30 to 35US delivered.. - for that price it's a decent low current (1mA res) DC clamp meter, but you will cycle that zero-button to the cows come home when pursuing DC readings down to the last mA to keep these hall sensors in check.

[Martin72]

Hi,

Is the EEVblog BM036 a good coice?

Lowest range is 60A....

A current clamp meter that can measure mA accourate is not cheap and cannot be cheap.
We (work) bought one from Benning to be able to measure standby currents.
We have it calibrated regularly and the accuracy is good.
But it is very sensitive, the maximum currents must not be exceeded, it can only measure up to 10A.
But it can also measure mA.

Benning CM11

[J-R]

Many clamp meters can measure uA through the test leads albeit with a pretty hefty voltage drop.  The BM036 does not have this uA feature, but the BM037 does.  However, the clamp is not going to give you any usable mA capabilities.

When I was searching for a DC mA clamp back in the day I settled on the Fluke 771.  It has 0.01mA resolution at the lowest range and can measure up to 110mA.  They are readily available on the second hand market.  0.01mA accuracy is possible with some care, 0.1mA is pretty easy and 1mA is basically guaranteed no matter the conditions.  However, it's very limited otherwise.  It's really made for a specific purpose (4-20mA loop signals).

Instead, could you make some kind of resistor shunt test fixture that could be easily inserted into your circuit?

[BILLPOD]

Check out the Owon CM2100 and the CM2100B, (which has Bluetooth capability).   I just got one in the mail, but haven't had a chance to test it out.    Several reviews on the interweb, (Tony Albus' is the best).

[HKJ]

With AC you can find clamp meters designed for earth leakage that can measure low current, for DC it is much harder due to the earth magnetic field. The best DC clamps I have seen can measure within a few mA (When used with care).
My preferred clamp meter for low current DC measurement  is the Benning CM11 (It can also do AC), it has 0.1mA resolution on both DC and AC.

[Pfriemler]

Got me a cheap Voltcraft with a 4A range. If you clamp the meter around the wire with no current, activate the REL function and then switch on the current, you may get a reading in mA range. But once you exceed the 4A only, you will get useless random readings. Hoped to get an mA clamp, but it´s almost crap.

[Kean]

Another vote here for the Fluke 771... if you must use a current clamp.  As mentioned it has a 0.01mA resolution, but realistically it can struggle with that and would require re-zeroing under any change in position or conditions.  Mind you, I just checked mine against a reference current source and it was pretty well spot on for several 1mA or 0.1mA steps, including up to the max 110mA.

I did use my Fluke 771 for low current measurements many years ago when I first got it, but I quickly realised it was much easier to just break the loop an insert a current meter.  Then even nano or pico amp measurements become (somewhat) easy.  And there are many designs published to assist with low burden current measurement.

Now my Fluke 771 is just something I would use for checking the occasional 4-20mA current loop as it was intended.

I have no idea how well the suggested Benning or Owon clamp meters would compare in real life, but the Fluke does way better than any of my UT210Es at low currents.

[Martin72]

I have no idea how well the suggested Benning or Owon clamp meters would compare in real life

"Next year" I can have a look at the calibration report of the Benning.
It is about ten times as expensive as the Owon and explicitly designed for low currents, so it will probably be good for something.
The Owon sounded so interesting to me that I ordered it and it should arrive tomorrow.
Then I can compare it with the current range of my 6.5 digit meter.

[linux-works]

and if you want linux remote control of that owon clamp, go to my github and enjoy.

https://github.com/sercona/Owon-Multimeters

[Martin72]

I recently found a current clamp meter that has a dedicated mA range and is still cheap (under 100):

[csuhi17]

The peaktech has a resolution of 1 mA and its accuracy is +/- 2.5 % + 30 dgt.
with a measuring range of 5000mA.
The Owon has a measurement limit of 2,000A, also on a 1mA scale. accuracy ±(2%+8dig)...

[Brumby]

As a cheapskate with not very demanding requirements, I can attest to the usefulness of the UT210E.

You really do have to consider ALL external sources of magnetic fields, but developing a technique and using the "zero" button has proven to give reasonably repeatable measurements. Measuring in the hundreds of uA isn't where it will shine, but - with a well practised technique - you might get some indicative measurements.

[Martin72]

The peaktech has a resolution of 1 mA and its accuracy is +/- 2.5 % + 30 dgt.
with a measuring range of 5000mA.
The Owon has a measurement limit of 2,000A, also on a 1mA scale. accuracy ±(2%+8dig)...

Oh, that makes it much more accurate, doesn't it?

@Brumby:
I also have a Uni-T UT210e here, so I can compare it.

[Someone]

As a cheapskate with not very demanding requirements, I can attest to the usefulness of the UT210E.

You really do have to consider ALL external sources of magnetic fields, but developing a technique and using the "zero" button has proven to give reasonably repeatable measurements. Measuring in the hundreds of uA isn't where it will shine, but - with a well practised technique - you might get some indicative measurements.

Wrap the/a wire n times around the clamp jaw, n times the sensitivity.

[Brumby]

[Wrap the/a wire n times around the clamp jaw, n times the sensitivity.

That applies to any clamp meter - and while it does improve low level measurements, it is not always convenient,  especially when zeroing.

[bastl_r]

using the "zero" button
Once you have done this, do not change the orientation significantly. Otherwise you will immediately have a huge measuring error.

[beatman]

Extech 380942 30A True RMS AC/DC Mini Clamp Meter.

[csuhi17]

That doesn't look bad either.
benning cm 10-pv

[wofritz]

I recently found a current clamp meter that has a dedicated mA range and is still cheap (under 100):

<Peaktech 4350>

I have this one.  It is working quite well even in the DC mA range. Problem is zeroing. Best results are obtained if you zero it in the circuit and don't change the setup after that. But that's not possible if you can not switch off the device under test, which might be the reason to use a clamp meter in the first place.

[Hydron]

I think mA resolution and careful zeroing is about as good as you can do without going to heroic efforts to minimise the gaps in the magnetic circuit (as the multi-kilobuck tek/hikoi/clone probes do, to the extent of lapping the core interfaces and using thin film hall sensors and nulling coils). Even those ones are pushing it for use at sub-mA resolution.

[HKJ]

I decided to check my Benning CM11 with a current source (Keithley 2460).
Short-term it only changes about 0.1mA, i.e. measuring 0.5mA it changes between 0.5mA or 0.6mA, but boosting the current to 1A for a short time (Maybe 10sec) may add a offset of a few mA*, i.e. requiring a new ZERO to get the low current reading correct again.
*This kind of offset is due to magnetizing the clamp, i.e. it will only occur first time or after a current direction reversal, I did play a bit with some clamp meters and magnetization here: https://lygte-info.dk/info/DMMClampDemag%20UK.html

The CM11 is much better than the UT210e, but the Fluke is probably better in the lowest measurements.

[HKJ]

Which Fluke has better DC measurement parameters than the Benning CM 10-PV? for the same amount of money?

https://www.benning.de/products-en/testing-measuring-and-safety-equipment/current-clamp-multimeter/pv-current-clamp-meter-cm-10-pv.html

The Fluke was mentioned earlier in the thread, it is a special purpose clamp meter, not a general purpose one and is probably much more expensive from new, but can be bought used.

[csuhi17]

Which Fluke has better DC measurement parameters than the Benning CM 10-PV? for the same amount of money?

https://www.benning.de/products-en/testing-measuring-and-safety-equipment/current-clamp-multimeter/pv-current-clamp-meter-cm-10-pv.html

The Fluke was mentioned earlier in the thread, it is a special purpose clamp meter, not a general purpose one and is probably much more expensive from new, but can be bought used.

I may have misinterpreted the description of the Benning that I linked to, which is why I deleted my previous question.
If I managed to understand correctly, then a
The uA measurement does not apply to the clamp meter...
The clamp meter measures with a minimum scale of 10mA.