DC Clamp Meter Questions - Page 1
Forum section: electronics / beginners

author: DW1961
author_rank: Frequent Contributor
timestamp: February 11, 2021, 06:31:09 am
content: I thought it would be really cool to have a DC clamp meter, so I requested one from Vine to review (Amazon's free product for review program).So, first off, nope, not for my applications which are all low voltage 2-3 amps or less. The meter only measures to 100mA or 0000.x. So, really not too useful. It's a 600-1000A meter.Link:https://www.amazon.com/gp/product/B08KXWLGD3That was my fault for not paying attention.Second, when measuring DC current, if I used the power wire, I got no reading. If I used the return wire, then it would read out ok. I'm assuming this is a DC thing?Third, the Clamp meter has an NCV function. However, when I tap the leads area, it goes off with beeps. The vendor sent another one out and said the tech said just not to tap it there--lol. It did the same thing, but not nearly as badly. I have another Chinese AC clamp meter, and I tested it by setting it to NCV and taping on it, and once in a while it would sound off too. Anyone know why that is, or is it just poor quality?As always, thanks!

author: thm_w
author_rank: Super Contributor
timestamp: February 12, 2021, 12:48:25 am
content: Return it and get a UT210E.QuoteThey should be the same.

author: SG-1
author_rank: Regular Contributor
timestamp: February 12, 2021, 01:25:20 am
content: Every NCV pencil type tester I have ever used, does the same thing. They are very sensitive to e-fields & the touching is probably producing a spike (static charge) in the e-field at the point of contact. I have used at least five different brands or models. Even my Flir DM284 does it when tapped near the sensor.

author: DW1961
author_rank: Frequent Contributor
timestamp: February 12, 2021, 02:40:51 am
content: Quote from: SG-1 on February 12, 2021, 01:25:20 amGood to know. Thanks for the information.

author: DW1961
author_rank: Frequent Contributor
timestamp: February 12, 2021, 02:42:07 am
content: Quote from: thm_w on February 12, 2021, 12:48:25 amStrange then, since this one wasn't. Good deal on that mini DC clamp meter. Just what I need. I'll keep an eye on Vine for one in the future.

author: floobydust
author_rank: Super Contributor
timestamp: February 12, 2021, 05:37:44 am
content: It's common for the iron jaws to get magnetized, then you getmagnetic hysteresishappening.Which manifests as the DC clamp meter cannot be zeroed, or it zeroes OK but is near clipping the A/D and reads low. Usually it shows up as a large asymmetry in readings that should be the same i.e. + or -1A when you flip the wire around- does not give the same reading.I see this in DC clamp meters in the 1A and less. A 600A-1,000A DC clamp meter I think only would be used reading car starter motors or maybe welding currents if it's got min/max.I demagnetize the jaws to fix this, but they can get re-magnetized with a single high current DC pulse, or a magnetized screwdriver etc. touching the jaws.You can also wrap say 10 turns in the jaws to get a 10X multiplier if you are working at the low end of the meter's range.

author: DW1961
author_rank: Frequent Contributor
timestamp: February 12, 2021, 05:51:00 pm
content: Quote from: floobydust on February 12, 2021, 05:37:44 amThat's exactly what it was ding on the positive side, reading really low. So you think it was because the jaws were magnetized. In any event, I was not paying attention because the meter really isn't for low current work. It only measures in 100mA increments. Once I REL'ed (zeroed) it gave me about the same as my other meter, except it was only reading .4 instead of .459 because that's all it can do. This is really, like you said, for high current applications.Well, again, thanks guys. Much appreciated when you can help pull off the blinders of ignorance.