Handheld meter robustness testing

[joeqsmith]

That was interesting to watch, thank you for making the video. I'm a bit puzzled though by one thing: Obviously Uni-T put in some effort into making the meter robust to transients, so how could they miss the ESD susceptibility? Or rephrased, how would the meter survive transients, but not ESD events? Is this because of the (presumed, on my part) much smaller rise time of static discharges?

In any case, it feels like they're stepping up their game. If you look at what they've been doing so far, the next generation of meters in a couple of years will probably be hard to fault, but cost a third of what a Fluke costs. Which will hopefully make Fluke and others think about some strategic improvements as well. And your videos as well as those of your fellow videobloggers sure help with making issues more visible

Thanks. 

I dug into the standards and still to be honest, I have no idea if they need to meet the 61326 standard.  All I ever seem to hear about is safety and 61010.  So, maybe they are fine not meeting it.   

I think what Saturation posted is spot on.  These are two completely different transients and what works for one may not work for another.   One thing the EMC standard is clear about, when it comes to ESD the product can not be damaged.  When we look at the 61010, I am still not sure if this is a requirement or not. 

Great job remediating the problem. 

For other readers, a big difference between the tests is that static discharge waveforms are in nanoseconds while the impulse waveform are in microseconds.   So the energies involved relative to human injury is mJ for static versus J for impulses, but to high impedance electronics, its still deadly.  Why Uni-T didn't take it into account is puzzling given the effort to get ETL listed, typically the ETL consultant would have mentioned it.

[joeqsmith]

Last of the pocket meters made it in.   Both the UT181A and the UT10 were ordered on the same date.  Maybe in a few weeks I'll have a chance to look at them.  Time to have a look at that 210E.

I did end up sending UNI-T a second email with links to the videos and my recommendations for the 181.  Who knows, maybe we will see a UT181B in the future. 

[joeqsmith]

What happens when your meter is used to measure the output of a microwave oven transformer?   

https://www.youtube.com/watch?v=eY5Rh2gokgg&feature=youtu.be

And you thought my tests were harsh!   

[RobertoLG]

ahh, it doesn't show the test, just the damaged meter...

[joeqsmith]

Yea, I know!  We were shorted!  I was reading the description.    If it were me, I would have left the cover off, pointed the camera at it, then connect the thing back up.   

I need a microwave transformer...

This happened to my multimetr after I have tried to measure voltage on secondary winding of a samsung microwave owen after replacement of a burned glas fuse. I do not know what I was fhought about that moment, but as I red later the voltage level on it is about 3 kV. Thanks god I still have both of my hands. As autopsy shown, it is only 1 ptc and couple of resistors inside, and this is all input overvoltage protection of this multimeter. I wrote an email to manufacturer but they use "ostrich policy" in their job. So, I writing about this for those people, who is going to buy this fake rated device. Do not do it, even for low voltage works, because some day, somehow, you may forget about CAT ratings, and stick it to mains, or worse house incoming power supply 380 V, but nobody will tell you that will happen after that!

[RobertoLG]

heh, I have one here lol, from an old 1600 watts microwave, the capacitor is rated for 2400 VAC , the magnetron too and no I won't kill my meter with it   

[joeqsmith]

Looks like a good sized transformer.   I wonder if any handheld meter would survive a 1 minute hookup.   

[RobertoLG]

Looks like a good sized transformer.   I wonder if any handheld meter would survive a 1 minute hookup.

ya, it's about 6 kilos, the microwave was almost as big as an old CRT TV, with no spinning plate.  the only way to find out is to do the test lol, and that guy from the video learned a lesson he'll never forget at least.

[SeanB]

I have a microwave sitting around........ Should i connect a cheapie meter I do not like to it on DC volts and see where the smoke comes out?

[rsjsouza]

Or take its guts, create a cheapie microwave gun and aim at the unloved DMM.

Something similar as to what these bozos did a while ago...

http://gizmodo.com/this-kid-took-apart-a-microwave-to-create-an-insane-an-1612804394

[joeqsmith]

Looks like TME is selling the UT71D for $170 US.  Not the cheapest handheld to kill this way.   

[gameru]

Looks like TME is selling the UT71D for $170 US.  Not the cheapest handheld to kill this way.

Only a couple things are cheap on TME.It's a good shop,but with high prices

[joeqsmith]

A viewer had asked about making lower current measurements in the 4 to 20mA range using the Fluke 17B+.   

https://www.youtube.com/watch?v=89HDlSq8WEg&feature=youtu.be

[Fungus]

Nice use of the current shunt on the Fluke 101. 

[joeqsmith]

With the 4-20, I would think the risk would be fairly low but you never know.   

Nice use of the current shunt on the Fluke 101. 

[Fungus]

Nice use of the current shunt on the Fluke 101. 

With the 4-20, I would think the risk would be fairly low but you never know.   

What's the risk? A burnt out resistor?

[Fungus]

I'm sure you can find a suitable high power shunt if you know the current range:

eg. http://www.ebay.com/itm/320757994835

[joeqsmith]

Working in an industrial environment and hooking up to anything with an unprotected device would have a risk.   Assuming your working in the range of 24V or less would seem like a risk.  With what I show, there is no blast shield, no fuse, the wires hang right out there for you to touch and the banana connectors are not what should be used.  A clamp would be much safer choice and because you are not going in-line would make things go quicker.   

Again, I think the risk would be fairly low but buying a meter that has all the protection built-in seems like a small price to pay if this is your job. 

Nice use of the current shunt on the Fluke 101. 

With the 4-20, I would think the risk would be fairly low but you never know.   

What's the risk? A burnt out resistor?

[blacksheeplogic]

Working in an industrial environment and hooking up to anything with an unprotected device would have a risk.   Assuming your working in the range of 24V or less would seem like a risk.  With what I show, there is no blast shield, no fuse, the wires hang right out there for you to touch and the banana connectors are not what should be used.  A clamp would be much safer choice and because you are not going in-line would make things go quicker.   

Again, I think the risk would be fairly low but buying a meter that has all the protection built-in seems like a small price to pay if this is your job. 

If you are measuring inline (not using a clamp) a DMM with a ma range is probably a good option if you have any concerns first. A number of process meters won't appreciate any excessive voltages on the terminals. Both of mine are rated for 30V/24ma MAX on the terminals with the meter being essentially a very expensive fuse in the case of an overload.

[joeqsmith]

I'm sure a few of you are wanting to see some meter carnage!    After all, watching a UNI-T survive 15KV gets pretty boring.   

I finally broke out the pocket meters and did a quick check on them.  Suddenly the Harbor Freight free meter does not seem so bad.   These are all CAT II 300V rated but my plan is to not change anything in the test setup.   They are small and while I have not had them apart yet, I have to believe these things are going to make a mess.   

Maybe over the weekend I can get something together.   So stay tuned...

[joeqsmith]

Having a look at the new pocket meters.   

[joeqsmith]

Much to my surprise, one of the pocket meters has actually been holding up rather well.   Imagine if you made some "high end" meter and it could not handle what a sub $20 CAT II pocket meter could handle.  Should have everything wrapped up today.   

[joeqsmith]

The last meter just won't die. I have the Dremel, X-acto and dope out.   Time for a break while things dry....   

[tautech]

The last meter just won't die.

Sub $20 meter.......  

Looking forward to this vid.......

[joeqsmith]

It finally died.  However there's not working dead, then there is 600 Joules of dead.         Looks like one more day of testing.