over current in clamp meter - Page 1
Forum section: electronics / testgear

author: hussamaldean
author_rank: Unknown
timestamp: November 25, 2018, 04:04:09 am
content: Hi all,I am planning to buy clamp meter to measure the current for motors, high power led and so on. but the question is what happen if the current was beyond the limit of the clamp meter. let say a clamp meter with 60A and the current in circuit was 100A ?will the meter get damaged or remains functional ?I know it is stupid question but I want to knowregards

author: 0culus
author_rank: Super Contributor
timestamp: November 25, 2018, 06:29:31 am
content: I would think it wouldn't be a problem since there is no actual electrical contact between the meter and the conductor you are measuring current through (unlike current measurements with a traditional multimeter). Assuming, of course, something else doesn't blow up.Fluke has some resources with FAQs:https://www.fluke.com/en-us/learn/best-practices/test-tools-basics/clamp-meters/what-is-a-clamp-meterIt looks to me like the primary consideration is choosing one that works in the ranges you are planning to measure.

author: graybeard
author_rank: Frequent Contributor
timestamp: November 26, 2018, 03:35:22 am
content: I would check the manual to see what limits the manufacturer specifies and stick to those limits. Since they designed it and if it is a quality piece of gear it should specify the maximum overload limits.You could blow a fuse in the meter since the clamp is a current transformer that causes a smaller current to flow in the meter, it would be an annoyance but not the end of the world.If you grossly exceed the maximum current rating of the meter it is possible you could induce enough heat in the core to cause damage. If the overload is of a thermally short duration it could be fine.It is also possible the core would saturate at the higher current peaks and be fine.

author: NiHaoMike
author_rank: Super Contributor
timestamp: November 26, 2018, 05:11:29 am
content: It might magnetize the core causing an offset until it's degaussed.

author: graybeard
author_rank: Frequent Contributor
timestamp: November 26, 2018, 09:03:41 am
content: possible, but unlikely with an AC signal

author: Fungus
author_rank: Super Contributor
timestamp: November 26, 2018, 09:11:01 am
content: Quote from: hussamaldean on November 25, 2018, 04:04:09 amIt's just a magnetic field, no permanent damage can occur.It might need degaussing afterwards if you went way over the limit though(depending on the clamp and how much you went over).

author: hussamaldean
author_rank: Unknown
timestamp: November 26, 2018, 09:59:16 am
content: Quote from: Fungus on November 26, 2018, 09:11:01 amthx a lot it will be 600A DC-AC TRMS oneI won't reach more than 20A in my experiments and maybe some other stuff for home usage like heater

author: Neomys Sapiens
author_rank: Super Contributor
timestamp: November 26, 2018, 11:40:48 pm
content: All of the above holds true for CLAMPMETERS only. When you use an external current clamp (multimeter accessory), which is supposed to have the multimeter operating in current mode, you have to take care not to leave it unconnected. Because in this case, you will have a large voltage on the clamp's secondary winding. The manufacturers warn about this mainly to avoid injury, but I assume that their open circuit voltage rating is only good for the nominal maximum current. In this case, open circuit + overcurrent might damage the secondary.Pure Hall Sensor clamps (and clampmeters) should be safe in this regard, whereas compound devices (like the fast current clamps from Tek etc.) are affected, because they have a secondary winding.

author: coppercone2
author_rank: Super Contributor
timestamp: November 27, 2018, 12:28:24 am
content: it sounds kinda like the clamp should have a circuit that interfaces with the MM to open a connection, or at least a enable button.

author: joeqsmith
author_rank: Super Contributor
timestamp: November 28, 2018, 03:44:50 am
content: I bought a UNI-T UT-210E clamp meter. One of the first things I did was crank up the welder. A few strikes and the meter would over range with no current. No damage. Just a quick degauss.I should mention that after that first test, there was enough offset that the Rel would not zero out the meter.

author: HKJ
author_rank: Super Contributor
timestamp: November 28, 2018, 07:24:53 am
content: I played a bit with magnetization on clamp meters here:https://lygte-info.dk/info/DMMClampDemag%20UK.html