Handheld meter robustness testing

[joeqsmith]

Dave reviewed the video and has approved it to be released.  I will allow Dave to comment on the findings.   

[EEVblog]

Dave reviewed the video and has approved it to be released.  I will allow Dave to comment on the findings.   

Thanks Joe, I commented on the Youtube video but will repeat that here:

SPOILER ALERT:
Thanks for the testing Joe. We think we may have uncovered a potential cause of failing at the 2kV impulse and will be looking into that. It was most likely the 2kV impulse on the ohms range that caused the failure at that point, as there is no mechanism whereby the Volts range could potentially fail at that voltage.
The meter is still under development as you mention, so changes are still on-going.
Even if it passed all the impulse tests, it will never be the best choice for those looking for the best high energy rated industrial meter (hence the lack of CAT IV rating, only CAT III, 600V max).
It is also being ETL certified to ensure full safety compliance of course.?

[imidis]

Thanks Dave and Joe

[kcbrown]

Even if it passed all the impulse tests, it will never be the best choice for those looking for the best high energy rated industrial meter (hence the lack of CAT IV rating, only CAT III, 600V max).

What??   But ... but ... 1.21 GW!!!

Surely it'll pass the kite string test...






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[EEVblog]

Even if it passed all the impulse tests, it will never be the best choice for those looking for the best high energy rated industrial meter (hence the lack of CAT IV rating, only CAT III, 600V max).

What??   But ... but ... 1.21 GW!!!

I'll pay that!

[jordanp123]

Looks like I'll be acquiring one, once they are released.

[Fungus]

Will David L. Jones be the next John Fluke? 

I think purple would be a better color.

[floobydust]

Troubleshooting 61010 impulse testing fails... don't impulse test because it's destructive and good luck finding out where the breakdown occurred.

My method is to use a HV power supply made of a car ignition coil and PWM circuit to generate mild HV. Or a high-pot tester.

Apply this to the circuit and you can hear/see the corona or make an arc. If the breakdown location is really elusive, do it in the dark but keep your nose away 
If you keep the HV applied for a long time (many seconds), ozone buildup occurs and the air breaks down at a lower level which can be misleading.
You can also place Kapton tape in the areas you guess the breakdown is occurring and look for results.

[Fungus]

Of course it's fast, it uses a flux capacitor!

(just don't go over 88Hz)

[EEVblog]

Troubleshooting 61010 impulse testing fails... don't impulse test because it's destructive and good luck finding out where the breakdown occurred.

Yes, tracking down the exact mechanism of the failure like this takes a huge amount of time, effort, and busted meters.

[Fungus]

The snowball test is a new one. 

https://www.youtube.com/watch?v=wkrbohiuUwU&feature=youtu.be&t=32m10s

[Fungus]

Of course it's fast, it uses a flux capacitor!

(just don't go over 88Hz)

The CEM meters I have are really bad.  So is the TPI. 

Whoosh?

[Crumble]

[...]
You saw a meter change 30X after being dropped?

The Metrahit changed about that ratio after being subjected to a magnetic field (I must admid I have not looked up the exact figure). I had assumed the drop test Fungus suggested was intended to provoke the relay changing this same way, that is why I mentioned it. Reading back the comments this might not have been the case. Excuse me for causing confusion... 

[joeqsmith]

[...]
You saw a meter change 30X after being dropped?

The Metrahit changed about that ratio after being subjected to a magnetic field (I must admid I have not looked up the exact figure). I had assumed the drop test Fungus suggested was intended to provoke the relay changing this same way, that is why I mentioned it. Reading back the comments this might not have been the case. Excuse me for causing confusion... 

This makes much more sense.  Thanks for clearing it up.  To be clear the ratio would be dependent on the input.  The higher in voltage, the larger the ratio because the meter just clamps it.  The PTC will just continue to drop more an more voltage.    And of course, the relay did not change states in the drop testing (I use that word very loosely)  I did but that does not mean that it can't happen.  That's why I suggest the shield does not solve the root problem.   

[Crumble]

No problem, sorry for that. I hadn't studied the exact workings of the relay, and just threw in the 30x remembering seeing about 4V when plugging into the 120V mains. The clamping behaviour is actually even worse, because it will then show roughly the same 4V when plugging it in to a way higher voltage than that. 

[joeqsmith]

No problem, sorry for that. I hadn't studied the exact workings of the relay, and just threw in the 30x remembering seeing about 4V when plugging into the 120V mains. The clamping behaviour is actually even worse, because it will then show roughly the same 4V when plugging it in to a way higher voltage than that. 

Yes, that is correct.   I have not heard anymore from them but sure would like to see that risk assessment. 

[joeqsmith]

Has anyone done any tests on the fuse kits Dave is offering?  I am interested in comparing data.   

[joeqsmith]

Video showing the 400mA ASTM fuse.

[Muttley Snickers]

I probably would have done it in the same manner anyway but for a minute there you had me worried using the Dremel free hand in that way, I haven't tried it with those ceramic fuses yet but with most of the other glass fuses you can just heat up the metallic tips with a lighter so as to melt the glue for removal of the ends, I have had to do this out in the field on the odd occasion but don't tell anybody.   

Also, and I know you have mentioned it in the past but those scratches on the Uni-T meter are just horrendous and not getting any better with time, I hope they are taking notice of your videos and how badly these screens are holding up, additionally it looks like somebody could do with a hair cut.   

[oh2hyt]

How close power measurement matches if you change 181A measure voltage between fuse input and amps jack of 121GW?

Also interested if 121GW does voltage measurement for power calculaltion referenced to amps jack or common jack (and estimates full burden voltage for calculation, or does it measure also full burden voltage)?

[joeqsmith]

Anyone else watch bigclive's last video and think it was going to be the end of that CEM meter?

[bitseeker]

Yeah, I jumped almost as high as his cats, despite knowing what was coming.

[MacMeter]

Once I heard "made for bad boys and girls", half way through video, I immediately began to wonder if JQS is coming up with some new MM testing protocols? If so, DYNAMITE!!!

[EEVblog]

In the mean time, someone was asking about how Dave could justify the 121GW as a $200 class meter.   The meter has a lot of unique features.    Here is a sneak peek of the VA feature being used to measure the power dissipation of the 400mA ASTM fuse.  Don't tell Dave I posted this. 

There was an error in your system setup here.
The error you are seeing was because you are not taking into account the insertion of the 121GW (and hence the small burden voltage of the 121GW) into your measurement. Your UT181 is not measuring at the same ground node a the 121GW is.
So it's a system connection error, not a meter error.
The 121GW can display it's own burden voltage (unique feature), but not in power measurement mode. But if you added that burden voltage and added to the voltage on the UT181 you should find that the two reading should match.?
Or of course simply connect the UT181 ground to 121GW ground.
This is why it was spot on at the low voltage, and then got progressively more error as you increased the current.?

[joeqsmith]

In the mean time, someone was asking about how Dave could justify the 121GW as a $200 class meter.   The meter has a lot of unique features.    Here is a sneak peek of the VA feature being used to measure the power dissipation of the 400mA ASTM fuse.  Don't tell Dave I posted this. 

There was an error in your system setup here.
The error you are seeing was because you are not taking into account the insertion of the 121GW (and hence the small burden voltage of the 121GW) into your measurement. Your UT181 is not measuring at the same ground node a the 121GW is.
So it's a system connection error, not a meter error.
The 121GW can display it's own burden voltage (unique feature), but not in power measurement mode. But if you added that burden voltage and added to the voltage on the UT181 you should find that the two reading should match.?
Or of course simply connect the UT181 ground to 121GW ground.
This is why it was spot on at the low voltage, and then got progressively more error as you increased the current.?

Funny, what you are calling an error in my setup, I was calling an error in the calculations.  Thanks for jumping in as I did not want to answer oh2hyt because I knew they were correct.  I just assumed this was a missing firmware calc.   

I was expecting the meter to measure the power at the load and would include the burden voltage as part of that calculation which is why it is connected this way.  Yes, if I wanted to measure the power dissipated by the load plus the meter, you are both correct and the three meters read very close.   I had tested it up to around 50 Watts (5A 10V sort of range).   I have not looked at AC.   

So, to be clear this is really what the plan is?  Not to display load power by compensating for the burden?