It is not my intent to diminish the work and findings of joeqsmith with what I am about to say. His tests show one thing and one thing only, ie the ability of a meter to survive his pulse tests. This is something to consider when buying a meter but it is not the only criteria that a newbie should used in selecting a meter.
No problem.
This may be all you took away from this experiment but there was a lot to learn. I understand, you sell products like hand held meters. I'm not suggesting you would ever add your own bias to make more sales. You just need to make sure that you understand what is going on before you use this information as part of your sales pitch.
Safety is important, but none of these videos demonstrated an unsafe condition that I could see.
That was never a goal. Comments like this are why I don't think you really understand what can happen. I covered this subject upfront. If you don't feel that there are any concerns when an arc is combined with a high energy source, so be it. Personally, I would not trivialize it to my customers.
Thanks for the video. The failure of the UT139C seems to have been either a faulty PTC, bad spacing on the tracks that caused an arc over and then the failure of the PTC which then overloaded the MOVs too many times and then every time after the MOVs were a dead short and caused the big flashes.
If you are willing, I think it would make good videos investigating the failure mode of at least some of the meters and see if they could be repaired by just replacing a part or two.
There is no reason to spend a whole lot of time attempting to repair low cost devices like these. Just buy a new one. The goal was to find a meter that would survive, then you wouldn't need to be so concerned about replacing it. I showed where most meters were damaged in the video.
That said, I did waste some time repairing the UNI-T UT90A. The control IC was still good. Three traces had vaporized. One diode was shorted, 2 resistors were open. I aligned it and it seems fine. Nothing I would give away because of the damage to the switch area.
Sounds like you are most interested in the UT139C. Q8, Q9, Q2, Q3, R42 and the main control IC are all damaged. While the heat cracked the insulation around the one PTC, both of them are still fine.
Most of the damaged meters were ran again at even higher voltages, causing even further damage to them.
I was amazed that you killed the Klein, I liked its small size/lack of features.
Klein Tools, not as strong as a set of channel locks!!
The case is glued together. Indeed, there is a relay in it. I had attempted to contact Klein, Fluke and AMPROBE by email. I would have returned the Klein to them if they wanted it. I am not sure what the problem is with it. It appears the source was damaged, not the input. I tested it again tonight after I ripped it (literally) apart. It appears the PTC itself will not withstand the voltage. It arcs and I am sure this caused the damage. Of all of the meters, the mechanical design of this thing is fantastic, except you can not service it.
Muxr and Fungus, I agree about the AMPROBE. It really is a nice meter for the price. I like it better than the Fluke. I would like to have have a higher end Fluke, Keysight and AMPROBE to try and destroy (and I don't mean drop it).
If I had any bias towards one brand during this test, it was with Fluke. Again, I have to admit, this low cost Fluke really has changed my 30 year old view of their products. Good job Fluke!!
Hi Joe,
Since you are skilled enough to build your own generator, and have demonstrated coupling voltage with the surges, I could use your advice.
I want to couple AC voltage with the surge generator I pictured in this thread. I've researched what inductor should be used to couple this, and 1.5 mH seems the most common recommendation. But, I also want a inductor that can handle a considerable amount of current. So, I found a few 10A inductors, but not a 1.5 mH. In the 10A rating, they have a 1 mH, and a 2.5 mH. Could you tell me which size inductor would be the best to use with the 1.2/50 pulse width?
Sorry, I can't be of help other than suggest your life insurance is paid up. I just don't know enough about it. It's not just the current and inductance, that's a lot of voltage. The company who built your generator may be willing to supply you with information on their networks. You may find it better to get the right network for your system.