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New Uni-Trend UT513 and UT61E do not mix

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I just picked up a Unit-Trend UT513 insulation tester for some specific uses but wondered about the leads on my multimeters and how my mulitmeters would stand up to high voltage. Do they stand up to 1000V? Well yes all survive this test. I can say that the UT61E does not like 2500V though!.

I get nice arcing across the selector dial traces on the UT33C and it works to spec afterwards. Not so on the UT61E. Nice buzzing sound, and then when restarted, not so happy anymore. What did I expect? Well I expected problems as the Unit-Ts have no MOVs or spark gaps on the inputs and it shows.

The UT61E now displays the ohms symbol on the voltage range, mF on the mV range, displaying random numbers, megohms on the miliamp and microamp ranges with overload. I am not blaming the meter as I did something clearly outside of its specifications but this does show you that perhaps he exclusion of MOVs or spark gaps is a cost cutting decision that will come to haunt the owner of the meter. A cheap little MOV would have prevented this damage, and it is damage that could occur by static discharge from a carpet.

I might see if there is some little passive that has failed on the input but I will not be too diligent. Maybe I will order another from Frankie.

I put some spark gaps in mine. Still wouldn't try 2.5kV across it on purpose!

No point checking passives, you've done the main IC in.

Yes, you probably fried the IC. I would still check the current limiting resistor and the PTC for damage, just in case.
How many amps does that UT513 deliver with a 2500V short? Probably a lot more than your Persian carpet.
My 71B has also got a spark gap now.

The UT513 says it is limited to less than 2ma. AT 2500V that is still a lot of energy for the chip to dissipate. I knew I was going to blow something up and I wanted to see what it would take to make the UT61E go silly. Yeah, I am sure the main chip is fried internally too. Too bad I didn't put some MOVs in first to test it and then without so we could see if they make a difference in this case. The UT513 will do 5000V at 1ma at least BTW.

Any meter I review from now on will be tested at 500V or 1000V depending on its claimed ratings.

Here a cheaper device to blow up your meters if the protection is bad, with 1000V 1Hz pulses at <2mA and 0.5 joule  ^-^

Wytnucls, a real Persian carpet is made with wool so it is less static than those nylon mixed factory made ones ;)


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