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    Help using dmm safety

    I has some electronics exp. My dmm uni-t UT61E
    Its manual http://www.uni-trend.com/productsdet...743&CateId=743

    So can this dmm be used to read volts over 1000v?

    I have done so with 500v caps, but nothing @ or over 500v.

    Will it break dmm? Can my test leads keep the voltage from zaping me?

    Thanks for your time

    Link to pdf
    https://drive.google.com/file/d/0B4J...RuQjdoVEk/view

    See page 6 and 16
    Last edited by cwolford; 03-04-2017, 06:30 PM.

    #2
    Re: Help using dmm safety

    Originally posted by cwolford View Post
    So can this dmm be used to read volts over 1000v?
    No. Almost all handheld modern multimeters can read up to 1000V. Over that, your mileage may vary depending on the situation.

    If you need to measure over 1000V, get the proper tool.

    I have done so with 500v caps, but nothing @ or over 500v.
    The UT61E doesn't have very good input protection (many threads/teardowns over at eevblog).

    Will it break dmm? Can my test leads keep the voltage from zaping me?
    Measuring high voltage can break the multimeter in many ways. Again, many examples and pictures at eevblog.

    If you measure high voltage (i.e. > 50V) on a regular basis, get a set of grabbers or pinchers so you can measure hands free.

    In addition, double and triple check your rotary dial and input jack settings before making a live measurement. If you have your multimeter set to measure amps and your probes are in the amps jack and you try to measure voltage, you could literally have a once in a lifetime experience.
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      #3
      Re: Help using dmm safety

      "If you measure high voltage (i.e. > 50V) on a regular basis, get a set of grabbers or pinchers so you can measure hands free."

      I assume one would hook up ever thing to take the measurement with the grabbers, then setup dmm then kick on the circuit?

      Never thought about this lol. Thanks I will get a set.

      Comment


        #4
        Re: Help using dmm safety

        I have the "GS" version of the UT61E.
        It is CAT-III rated for 300v and CAT-II rated for 600v.
        I would only use this meter for low energy circuits.

        The specifications on their website say it is rated for up to 750VAC and 1000VDC.
        But that said there is a reason that the "GS" version (which has better fuses and protection) is downrated compared to the non GS version!

        I would throw away the original probes and get a set of Fluke probes with screw-on alligator clips.
        The included ones with mine where very flimsy and actually had intermittent connection anyway...

        But if you need to measure high voltage circuits do get a proper high voltage probe instead!
        (So instead of 1000v the meter will read 100v for example with a 10:1 probe).
        Last edited by Per Hansson; 03-05-2017, 03:43 AM.
        "The one who says it cannot be done should never interrupt the one who is doing it."

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          #5
          Re: Help using dmm safety

          You can always roll your own high voltage probe. Start with something like this.

          http://www.electronicsurplus.com/bem...ic-1090meg-ohm

          If you feel uncomfortable doing it, DON'T!

          Comment


            #6
            Re: Help using dmm safety

            Originally posted by Per Hansson View Post
            I have the "GS" version of the UT61E.
            It is CAT-III rated for 300v and CAT-II rated for 600v.
            Yes, that is also discussed over at eevblog. The GS version has better input protection than the non GS version and is more likely to meets its 300V and 600V rating.

            BTW, the Brymen BM869 is UL listed to 1000V CATIV, but when subjected to high votlage (i.e. > 1000V) like this badcap member did, look at the damage

            https://www.badcaps.net/forum/showthread.php?t=45936

            Just one of the pictures from that thread below. Badcaps member won't say what he was measuring, but look at the damage.

            And this is from a company that designs well made multimeters and gets many third party certifications.
            Attached Files
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              #7
              Re: Help using dmm safety

              @OP, if you want to learn more about multimeter input protection basics, see Dave Jones' video

              https://www.youtube.com/watch?v=zUhnGp5vh60
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                #8
                Re: Help using dmm safety

                Originally posted by cwolford View Post
                Can my test leads keep the voltage from zaping me?
                If your test leads have any break in the insulation or exposed wiring on the sleeves, watch out!
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                  #9
                  Re: Help using dmm safety

                  retiredcaps, yes I remember that thread, read it also on eevblog.
                  Consider what kind of damage could have been done if a meter with a fake CAT rating at 1000v had been used like the first batches of the UT61E for example.
                  Scary to even think about when you see this picture and imagine your hand holding the meter!
                  "The one who says it cannot be done should never interrupt the one who is doing it."

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                    #10
                    Re: Help using dmm safety

                    So thanks for the info, a lot to take in. I know better than to just start messing around, I have had a few class in the matter.

                    So I need to test a transform for a back light issue, and my kids keep me from browsing the net for days on end finding good info for diy. Any one know of a good dig high voltage prob?

                    I assume I can make it and test it on 100v or 200v to make sure it work right.

                    Never thought about a voltage shunt. That's basically what it is right. Like when you need to measure amps?

                    Thanks for your help guy and girls.

                    Comment


                      #11
                      Re: Help using dmm safety

                      Originally posted by cwolford View Post
                      So I need to test a transform for a back light issue,
                      If you think the transformer is bad, you don't need to measure the ACV (likely 1100 to 2000V) of it. There is a safer way.

                      Looking at your Phillips thread post #1 only, you may have 2 seconds to black? I wrote a guide on how to test the inverter transformer by using the ohms functionality of your meter. See the sticky.

                      PS. I no longer participate in fixing TV/LCD monitor threads. I did that for almost 4 years and despite writing guides and helping, no one seems to read them so I gave up.
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                        #12
                        Re: Help using dmm safety

                        Originally posted by retiredcaps View Post
                        If you think the transformer is bad, you don't need to measure the ACV (likely 1100 to 2000V) of it. There is a safer way.

                        Looking at your Phillips thread post #1 only, you may have 2 seconds to black? I wrote a guide on how to test the inverter transformer by using the ohms functionality of your meter. See the sticky.

                        PS. I no longer participate in fixing TV/LCD monitor threads. I did that for almost 4 years and despite writing guides and helping, no one seems to read them so I gave up.
                        Going to read it now. I have no clue what is part of he back light circuit. I will test what I am pointed at or replace the parts etc. I don't have the skill yet to know how to track down all the things in that circuit.

                        I am grateful for people like you. Thank you so much.

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