Clamp current meters and why lack of DC current?

[vinlove]

I have just got a clamp meter delivered from online seller. It said on the listing "AC/DC Voltage Current ... blah blah" so I thought it would do both AC DC Current, but found out it does only do AC Current.  No DC Current. Because of this, I will be returning the meter for full refund.

Why do they not include DC Current capability in the meter?

I was looking at many other clamp meters, and most of them only does AC Current. Why do they do that?

[ogden]

Would be nice for you to be more specific because there are many clamp current meters with both AC and DC measurements. Anyway your question is answered here:

[vinlove]

My point of the question was simple and specific = why many clamp meters do not have DC current capabilities?

You can see them on all online sellers clamp meters. Some do include both AC and DC current capabilities, but many of them don't.
My use of clamp meters would be more for DC current measuring, so it was pointless buying AC current only meters.

And they mention in the listing as if it is for AC and DC current, but when you get it in hand, it is not.


Thanks for the vid. It looks like about how clamp meters work, not why many clamp meters on the market do not have DC current capabilities?

[BillB]

My point of the question was simple and specific = why many clamp meters do not have DC current capabilities?

It depends on how they are constructed.  Cheap AC clamps may be nothing more than coils.  AC/DC clamps use hall-effect sensors with smarts for conditioning.  See here:

https://www.transcat.com/media/pdf/CurrentProbeSelectionGuide.pdf

[Kleinstein]

An AC current clamp can be relatively cheap and still good performance.
A DC clamp function needs a magnetic flied sensor and a more demanding core material and mechanics and is thus more expensive. Still the performance at low current is usually poor, especially at low currents.  The video describes the problem quite well.

So DC clamps are rare and more expensive special instruments.

[eKretz]

Exactly right Bill. The clamps with AC current measurement only are measuring current with a coil of wire - which can't measure DC current. Hence, those meters don't measure DC current.

To measure both AC and DC current, the clamp needs to be made with a hall effect sensor, which as noted adds to the complexity and cost.

[janoc]

If you want a cheap clamp that can do DC current, then UT-210E may be a good candidate:

http://www.uni-trend.com/index.php?m=content&c=index&a=show&catid=189&id=231

It has a 2A range, so it is useful even for low currents  and not only for an electrician.

[Terry01]

If you want a cheap clamp that can do DC current, then UT-210E may be a good candidate:

http://www.uni-trend.com/index.php?m=content&c=index&a=show&catid=189&id=231

It has a 2A range, so it is useful even for low currents  and not only for an electrician.

Ill 2nd for the UT-210E. There are plenty discussions on the forum about this meter and a couple of hacks too. I have 1 and it's a great wee meter for what it is.

[vinlove]

Great explanations, thanks.

Imagine buying DMM with just AC voltage capability only?   It shouldn't be called then MM anymore. MM means all functions are in one box, I would imagine.

So getting just AC Current Clamp Meter just sounded odd to me.  I can see it requires more sophisticated parts for DC Current, but these days price of these parts and modules keep coming down, hence we could even afford a 20 dollar DSOs, and 10 dollar FGs, Freq counters ...etc.

I have returned the AC only current clamp meter, so will need to shop for another one, = definitely with both AC and DC current clamp meter.

[CDaniel]

You must understand that this is primary a professional's tool , and a traditional electrician simply doesn't need to measure high DC currents , another reason why even big companies like Fluke still sell some only AC clamp meters.

[jfiresto]

... I have returned the AC only current clamp meter, so will need to shop for another one, = definitely with both AC and DC current clamp meter.

If you are in Europe or Asia and after a professional, general purpose meter, the Benning CM-11 was the least expensive unit I could find when I was looking a couple years ago. It pretty much provides +/-1 mA + 1% absolute accuracy on the lowest DCA range. Originally it was to do better than that, but achieving such accuracies is hard.

[Bratster]

If you want a cheap clamp that can do DC current, then UT-210E may be a good candidate:

http://www.uni-trend.com/index.php?m=content&c=index&a=show&catid=189&id=231

It has a 2A range, so it is useful even for low currents  and not only for an electrician.

Ill 2nd for the UT-210E. There are plenty discussions on the forum about this meter and a couple of hacks too. I have 1 and it's a great wee meter for what it is.

I'll third for the UT-210E, it's a nice little current meter

Sent from my Pixel 2 XL using Tapatalk

[vinlove]

If you are in Europe or Asia and after a professional, general purpose meter, the Benning CM-11 was the least expensive unit I could find when I was looking a couple years ago. It pretty much provides +/-1 mA + 1% absolute accuracy on the lowest DCA range. Originally it was to do better than that, but achieving such accuracies is hard.

That looks a great clamp meter, but wow price seems very high.  I am just a hobbist, and learner, so I don't need highest spec and quality instruments for professionals.

But I thought there are many situations where DC current is important, for example, when even simple task like battery is being recharged, sometimes I don't know whether charging is working or not without any measurement.  In that case, I could measure the DC current from the charger, and know whether it is getting charged or not.

Because DC current varies according to its charging state, and  without having to break the circuit and insert meter, hence using clamp meter would be handy thing, if it works

It is very useful to be able to measure DC current in many occasions like that, and it is just one example.  Also when recharging is finished, the DC current from the charger will read 0A.

[Martin72]

I'll third for the UT-210E, it's a nice little current meter

Here a comparison I did between UT210E and ZES LMG 670 ( Base Accuracy 0.1%, Price 30000€) on 50/400Hz:



Amazing performance for it´s price.

DC-current comparison following after my holidays.

[bob91343]

Measuring direct current with a clamp meter isn't impossible but it won't work in the usual manner.  Its basis is a transformer, which won't go to dc.

I have a clamp-on meter that measures dc.  But it's a sophisticated HP unit that is line powered.  No transformer here, but a circuit that matches the magnetic field in a feedback loop.

My ac clampon meter is simple and cheap but won't work for very low frequencies or for dc.

A little thought about the principles of operation will reveal the reasons.

[IanB]

And they mention in the listing as if it is for AC and DC current, but when you get it in hand, it is not.

It most likely measures DC current through the probes, just not with the clamp. This will be clear if you look at the specifications and not just the headline.

Actually, "everyone" knows that regular clamp meters do not measure DC current with the clamp. You have now become part of "everyone" 

[bitseeker]

The UT-210E is a good choice for home and hobbyist use. Just note that the hall effect sensor is very sensitive. For best results, null the meter prior to taking each measurement and don't move it or the wire during a measurement.

Variations in the magnetic field in the clamp and around the meter will affect your readings. Hence, the position and location of the wire within the clamp, the direction of current flow, the orientation of the meter, other nearby current-carrying wires, magnets, motors, etc., and even build up of magnetic flux in the clamp can cause values to be different.

Clamp meters are handy and good to have, but they do require additional attention, especially with low currents.

[vinlove]

UT-210E seems getting good reviews.

I managed to order a lot cheaper one called Proster 6000 count.  It does AC DC Current.
Yeah you must read the specs. real carefully, not just main descriptions.  But why can't they write the main descriptions accurately, and allow us saving time?

Other applications I could use DC clamp meter would be for automotive problem diagnosis and check ups, where you could just clamp the meter, and read voltages and currents. Would be so handy.

I was checking voltages on my car's Oxygen sensor leads, and it was nightmare using DMM with probes because the access hole was tiny. Clamp meter which works on dc voltage and current would have done great service for the job.

[graybeard]

UT-210E seems getting good reviews.

I managed to order a lot cheaper one called Proster 6000 count.  It does AC DC Current.
Yeah you must read the specs. real carefully, not just main descriptions.  But why can't they write the main descriptions accurately, and allow us saving time?

Other applications I could use DC clamp meter would be for automotive problem diagnosis and check ups, where you could just clamp the meter, and read voltages and currents. Would be so handy.

I was checking voltages on my car's Oxygen sensor leads, and it was nightmare using DMM with probes because the access hole was tiny. Clamp meter which works on dc voltage and current would have done great service for the job.

The Proster if I read the specs correctly the least significant digit in current mode is 100mA  the UT-210E is 1mA, 100X more sensitive.  The UT-210E is far more useful.

[vinlove]

The Proster if I read the specs correctly lest significant digit in current mode is 100mA  the UT-210E is 1mA, 100X more sensitive.  The UT-210E is far more useful.

I could not find official quoted spec. for the least sig digit in current mode in the listing both Proster and UT-210E.  Maybe you could supply the link for the spec.?

Two points on the UT-210E would be,

1. Good reviews mostly, but some concern is its build quality, that it seems made with flimsy parts and lousy control knobs.

2. Not sure how useful it would be for home diy use to get 1mA accuracy.   Mostly I seem happy reading in A and 0.1A.  Most of little devices in house such as phones and chargers and radios are running 100mA - 1A.  My phone charger runs at about 800mA - 900mA.

Is there any device or parts which runs at 1mA - 9mA ?

[BravoV]

Put it simple, if you are looking for "cheap" say <100 US bucks for a new, current "clamp" that can do DC measurement reliably at below 1 A with mA resolution, then forget it.

[ogden]

Imagine buying DMM with just AC voltage capability only?   It shouldn't be called then MM anymore.

Yes you are right. Clamp meters are indeed Clamp Meters, not Multi Meters. DC current option became popular/widespread only when low cost solid state hall effect sensors became widely available.

I can see it requires more sophisticated parts for DC Current, but these days price of these parts and modules keep coming down, hence we could even afford a 20 dollar DSOs, and 10 dollar FGs, Freq counters ...etc.

Yes, it is happening with clamp meters as well. Today decent <= 50$ clampmeter usually offers everything - AC/DC current and AC/DC voltage measurement while 20 years ago you could only dream about such.

[vinlove]

This is a real detailed review on UT-210E, and it doesn't seem much different from the Proster Clamp Meter in specs.

https://lygte-info.dk/review/DMMUNI-TUT210E%20UK.html

[ogden]

This is a real detailed review on UT-210E, and it doesn't seem much different from the Proster Clamp Meter in specs.

https://lygte-info.dk/review/DMMUNI-TUT210E%20UK.html

Please comment how you came to that conclusion?       

UT-210E have 100, 20, 2A ranges. Down to 1mA resolution and 3%+10_counts accuracy @2A range. Proster don't even have multiple ranges for current. To be honest, I can't even find any specs for that... thing. Well... except clamp opening 28mm 28m if it counts 

[vinlove]

Please comment how you came to that conclusion?       

UT-210E have 100, 20, 2A ranges. Down to 1mA resolution and 3%+10_counts accuracy @2A range. Proster don't even have multiple ranges for current. To be honest, I can't even find any specs for that... thing. Well... except clamp opening 28mm 28m if it counts 

I didn't conclude.  I had an impression from the review by quick glance to it.

On the Proster 6000 count clamp meter, you could be right. I couldn't find any specs at all. I have cancelled the order.