DC clamp meter

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Old 02-17-20, 12:25 PM
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DC clamp meter

Hello

I have a TES-3092 AC/DC clamp meter.
For DC current mode, there is a button to zero the display, but this gives random negative results, rarely zero.
Maybe the jaws have to be de-magnetized?
Any one have an idea what I can try?

TIA
Marty
 
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Old 02-17-20, 12:36 PM
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Welcome to the forums.

That is the way most DC clamp meters work. With AC there is a large alternating magnetic field that is easy to measure. There is no alternating field with DC.

In DC current mode....Hall effect sensors are used to sense the magnetic field caused by the DC current flow which causes a small voltage across the Hall effect sensor. This small change is hard to measure and makes the meter very sensitive to external influences.

Clamp on DC amp meters are not used for an exact measurement. You would use an inline wired meter for that. For a quick average reading the clamp on should be close enough.
 
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Old 02-18-20, 11:04 AM
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Thanks.
That still doesn't explain why I need 10 tries to get it down to a usable value, usually -0.3 at best.

Regards
 
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Old 02-18-20, 03:26 PM
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Hall effect sensors used in DC clamp meter are influenced by earth's magnetic fields as well. You will never be able to get stable 0.

The best way to measure is to clamp on the wire you want to measure and zero it before connecting the load to the wire. Do not move wire around.

Is -0.3 you get in mA or A ?

Your meter has 0.1A resolution with +- (1.5%rdg + 2dgts) at 200A range.
The fact your meter has such a big range tells me it probably will be very in accurate in measuring small currents.

I would not use DC clamp meter for measuring anything smaller than a few amps.
 
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Old 02-18-20, 06:09 PM
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The further you use a DC clamp on meter from anything AC operated the easier it will be to zero.

I owned a mobile electronics shop for many years. I used several clamp on DC meters for rough current measurements in vehicles. It was always easier to zero them out in a car away from AC magnetic fields.
 
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Old 02-21-20, 05:01 PM
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Thanks guys.
.

But I repeat, it can take 10 tries to get it down to a usable value. Sometimes its as high as +/-2.x amps. Never the same twice. Why is it soo random?.
I've searched extensively on the 'net, but am not able to find the owners manual.

Thanks
Marty


 
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Old 02-21-20, 08:23 PM
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Sorry...... can't offer much further help.
I looked for a manual too but a lot of Chinese products don't offer online manuals and have little to no online technical information. They don't even offer one on the company website.

TES products
 
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Old 02-22-20, 06:32 AM
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Who designed the internal circuit? To get a measure of reading stability, one must choose op amps with good input offset voltage and current stability with temperature. Of course, the Hall effect device must be stable with both temperature and external mag fields. The zero circuit may also play into why u need to push the button many times to get very close to a zero read.
what full scale range is displayed when you see 2amps offset?
For more info, research instrumentation amplifiers😁
 
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Old 02-22-20, 11:51 AM
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not sure what your measuring exactly and maybe you want the clamp on feature but would imagine a standard amp meter would be a lot better.
 
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Old 02-24-20, 06:54 AM
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Hey Alan:
I am measuring current in my car at the battery. Not practical to go in series; I would need a shunt to be safe. This is a perfect application for a clamp meter.
Regards
 
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Old 02-24-20, 11:35 AM
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I would recommend getting another clamp meter with narrower range. They usually are more accurate for lower currents. I had a good luck with Uni-T models, although it still is not as good as other big name companies.

Also, you don't really need a shunt to measure car battery draw unless you are measuring starting and charging current. Connecting multimeter in series is perfectly fine for measuring parasitic draw and are more accurate.
 
 

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