Cheap Chinese multimeter and high voltage AC - Page 1
Forum section: electronics / testgear

author: synapsis
author_rank: Regular Contributor
timestamp: July 12, 2014, 06:03:07 am
content: I had a cheap Chinese multimeter (same one with the transistor tester that's almost everywhere) that I damaged when I accidentally sent 11kV DC through it. It killed the DC reading, but AC still worked fine. I just bought a Casio camera to try out the slow motion ability, so I decided to send the multimeter off in a "scientific" way. Since it's a little relevant to the forum, I figured I'd link it here.The only way I could get an arc to come out of the meter was to take the back rubber cover off and put it on a copper plate. It held up surprisingly well physically. Until the fire started.

author: SeanB
author_rank: Super Contributor
timestamp: July 12, 2014, 08:00:20 am
content: OOps, it arced over for some reason. I saw a Fluke 77 that was accidentally used on 11kV, it had a very clean board with no copper traces on it, and a copper plated case. It came in and they asked if it was covered by the warranty........ Funny thing is the only parts that survived were the display, the battery and the 2 HRC fuses.

author: Neilm
author_rank: Super Contributor
timestamp: July 12, 2014, 04:46:12 pm
content: I once had to test a very cheap meter my company was considering re-branding with our logo. We did the surge test required by 61010, but at less voltage as we didn't have the equipment to do the proper voltage. I didn't think it passed for about half a dozen reasons so wanted to try it at the 4kV we could do before going to a proper test house (and paying).for those who don't know, the test involves superimposing a spike (4kV in this instance) on live mains (440V on our setup). The idea is that the spike starts the breakdown and the mains supplies the energy.The result was a very loud explosion that took out the trip to the 100A trip. There wasn't much of any of it left afterwards.The second best was another cheap import - same test gave a loud bang and explosion escaped through the case join and would have burnt anyone holding it. When I took that apart, most of the chips had the tops missing but all that was left of the microprocessor was a few of the bond wires hanging in mid air.

author: Electronics-Repairman
author_rank: Contributor
timestamp: July 12, 2014, 05:15:32 pm
content: As much as I'm not a " I must have a certain big brand person" , I don't think Chinese cheap meters and high voltages go together, I bought a Gossen Metrawatt, I'm not recommending them, I've just always liked German engineering, even if it is expensive.

author: synapsis
author_rank: Regular Contributor
timestamp: July 12, 2014, 05:44:49 pm
content: Quote from: Neilm on July 12, 2014, 04:46:12 pmI've been thinking of hooking it up to my capacitor bank (that'll break the case for sure), but I'm still trying to find a way to discharge it from a control panel. The Chinese meter used to be semi-permanently on the bank to show charge before I put an analog meter on it.I'd try the mains spike, but I'm not well versed in AC enough to figure out how to do it with what I have laying around.

author: pickle9000
author_rank: Super Contributor
timestamp: July 12, 2014, 06:13:50 pm
content: Quote from: Electronics-Repairman on July 12, 2014, 05:15:32 pmThis falls under the category "no win", 5 dollars or 500 dollars it would die. Try hitting a Fluke with a sledge hammer...

author: Electronics-Repairman
author_rank: Contributor
timestamp: July 12, 2014, 06:26:20 pm
content: Quote from: pickle9000 on July 12, 2014, 06:13:50 pmVery True I should have read the post more carefully, for some reason I thought it was a house mains test, I suppose you could have 4KV if you had an electric chair in the cellar, I have known ordinary 240v line mains destroy a cheap chinese meter, which what I based my reply on , see I'm suffering engineer disease now, of not reading post in full

author: Bored@Work
author_rank: Super Contributor
timestamp: July 12, 2014, 07:50:51 pm
content: The point is not the meter surviving. The point is you surviving.

author: echen1024
author_rank: Super Contributor
timestamp: July 13, 2014, 02:32:58 am
content: Quote from: Bored@Work on July 12, 2014, 07:50:51 pm