Handheld meter robustness testing

[joeqsmith]

Every meter I have looked at that has survived has some type of down stream protection.   With the Keysight meter,   we don't know what the entire circuit is nor do we know how it would stack up against all of the other meters.

[joeqsmith]

http://www.amazon.com/Morris-59050Vage-Continuity-Tester-12-300V/dp/B005BH6HRM

So your touching the side metal contact with your body and jamming it into a live circuit? 

[Lightages]

Yup, just like those neon lamp live circuit testers.

[Muttley Snickers]

I see an opening and excuse to post these pictures, no teardown was required as it seemed to be an incorporated feature.....

[joeqsmith]

I see an opening and excuse to post these pictures, no teardown was required as it seemed to be an incorporated feature.....

  Nice!   I bet where the leads solder in would jump.  Maybe if we were lucky, it would go from the red trace to the neon bulb first, then to the black for some added excitement.         Then the leads look like they would light up.   

Sound like Lightages has one that uses the humans body to complete the circuit rather than the leads.  Any pictures of this one?

The one I have is marked P-85.  Its rated for 12 - 440 volts AC/DC.   The Morris Products 59050  looks like it and is rated for 440 as well.   

It uses a couple of A76 button batteries.  No power switch.   It detects continuity around 6Meg.  Solid on at 2Meg.  Short circuit current is about 500nA.   If you supply 220VRMS to the across the inputs, the current is about 4.9uA   I tried the piezo grill starter then maxed out the new generator on it but it would not breakdown.     That was with nothing in series.     So I used the old generator set to 12KV and it still works.     

[joeqsmith]

While looking for something with neon bulbs that goes through the human body, I came across this UNI-T CAT IV 600V rated and another banned member.     

Could this be the 1st UNI-T that can actually survive on the new generator?   I think we will find out..
https://www.eevblog.com/forum/testgear/%28-product-review-%29-uni-t-ut15c-volt-stick-ip65-cat-iv-600v/

[joeqsmith]

I had been asked about running a Vichy VC99. Unless anyone is aware of a Vichy meter that is CAT III 600 rated, I can't see a reason to try one.  I would need to change the impedance and have a new section just for CAT II class or just run it with the 2 ohm source.  The CAT III meters have a hard enough time surviving. 

[joeqsmith]

2016 is starting out on a good note.  A new camera has been added to the mix.    A GGT (glass gas discharge tube) has been added to the test jig.   Will it survive the half cycle line test?  Will it even survive the basic test?  Sure looks pretty delicate. 

The first of three new meters arrived today.  Hint, it's a brand I have never ran,  costs more than a shot of Dewars 18 year old scotch at the bar,  uses gas discharge tubes and you know the plan is to see what it takes to damage it. 

So stay tuned. 

[fanOfeeDIY]

So stay tuned.

I will.

[joeqsmith]

Finally trying out the new camera.  My plan is to make up my own opto-coupled trigger cable that will be driven from the transient generator.   To start, I plan to use the signal generator to output a burst of 1KHz pulses into a counter.  The signal generator's trigger out will trigger the camera that will be pointed at the counter.  Then I should be able to determine the trigger jigger and latency.     

This video shows a glass type gas discharge tube at low speed.  Then I setup the counter at 1KHz and recorded at 240 and 960 fps.  Looks like it can almost keep up at 960 as expected.   Picture looks pretty poor.   Guessing it's an operator problem...

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

[Stupid Beard]

This video shows a glass type gas discharge tube at low speed.  Then I setup the counter at 1KHz and recorded at 240 and 960 fps.  Looks like it can almost keep up at 960 as expected.   Picture looks pretty poor.   Guessing it's an operator problem...

The picture quality issue might be insufficient light. You generally need a lot more light at faster frame rates. I am by no means knowledgeable in that area but that's what it looked like to me.

[joeqsmith]

This video shows a glass type gas discharge tube at low speed.  Then I setup the counter at 1KHz and recorded at 240 and 960 fps.  Looks like it can almost keep up at 960 as expected.   Picture looks pretty poor.   Guessing it's an operator problem...

The picture quality issue might be insufficient light. You generally need a lot more light at faster frame rates. I am by no means knowledgeable in that area but that's what it looked like to me.

I am guessing you are right.  The old Cannon I use will get real grainy like this even with stills in low light.   The parts to make the trigger for the camera are now all on order.  I had not realized the mini-USB they use is actually a 10-pin until after I had ordered some standard 5 pin ones.    But the two connectors for the transient generator are here so I can get started making changes to that.   One connector will be a standard 50 ohm output, the other will be an isolated type for the camera.   

In retrospect, attempting to build the generator on old technology was not the brightest idea I have had.   There are about 50 bytes if code space left and no I/O pins to make this programmable trigger.      

I have a 22V10 on the board with one unused input that I plan to use to make a multiplexer with a few of the other signals and hope to somehow cram it all in there.   

The other two meters I wanted to run also arrived.  Lots to do.....

[joeqsmith]

FFE7 to FFEF is still free....       Just to be clear, the ROM starts at F800, or 2K total.   

I ended up putting two trigger outputs on the generator.  One is a programmable pre-trigger that will drive the high speed camera, the other is at the time the transient is fired.   Both are just 5V 50 ohm outputs.  I'll make a separate circuit for the camera. 

trigger1: two additional BNCs for the pre-trigger and trigger
trigger2: added pre-trigger  to display, shown at 200ms
trigger3: trigger outputs.   bottom trace rising edge is the pre-trigger.  200ms to trigger rising edge (top trace) 

Joined a camera forum and asked about the Sony's remote.   May have to modify the camera to make this work.      Hope to have the Sony remote and a few other parts next week and I can start playing with it. 


01506                         *  INVALID INTERRUPT REQUIESTED
01507                         *
01508  A ffe6 3b              INVALID_IRQ RTI         

M6801 Portable Cross Assembler  0.05  Page 31
 Sat Jan 16 20:16:13 2016 
Options - MD,MC,NOG,NOU,W,NOMEX,CL,FMT,O
 
LINE   S PC   OPCO OPERANDS S LABEL    MNEMO OPERANDS COMMENT
01509                         *
01510                         * INTERRUPT VECTORS
01511                         *
01512  A fff0                          ORG   IRQ_VEC  FFF0 - ROM
01513  A fff0      ffe6     A          FDB   INVALID_IRQ SCI

[joeqsmith]

Strange UNI-T ad where they go after Fluke. 

[PedroDaGr8]

Strange UNI-T ad where they go after Fluke. 

Wow, that is truly truly weird.

[joeqsmith]

I need to drill a few more holes in my custom made camera mount.      The last parts for the trigger should be in tomorrow.  Won't be long now.....

In the mean time, finally some fire and smoke....  In this video, I put the meter proto board the test again and capture the results with the new camera.   

[joeqsmith]

Finished up the remote and tested the camera's trigger delay.   

https://www.youtube.com/watch?v=jNF-j2B8caU&feature=youtu.be

[joeqsmith]

And finally, the new camera with modified remote is connected to the surge generator for the very first auto trigger....   And it works!!! 

I'm thinking it's time to look at a meter with some GDTs in it! 

[joeqsmith]

One of the meters I wanted to run was the UNI-T UT15C VoltStick.   The UNI-Ts have been some of the worst meters I have looked at and this one in particular has a CAT IV 600 rating and it basically just reads voltage so you would think it would be very robust.

There is a review of it on this site
https://www.eevblog.com/forum/testgear/%28-product-review-%29-uni-t-ut15c-volt-stick-ip65-cat-iv-600v/

Will it overthrow 5Ky's Fluke 107??? 

[joeqsmith]

I like the picture they used for the packaging of the UT15C.  Hope you enjoy the review.

[Fungus]

I thought the continuity test would be the failure point but it's the only thing that survived. 

Quite a surprising amount of components inside it for such limited/low-accuracy functionality. 

[joeqsmith]

I thought the continuity test would be the failure point but it's the only thing that survived. 

Quite a surprising amount of components inside it for such limited/low-accuracy functionality. 

Hey there Mr Fungus.   I really thought this was going to be the first UNI-T that survived beyond 5ky's Fluke 107 or at least hung in there with the low end Flukes.   Mainly because of the CAT IV 600V rating on it and the it appears to be purpose built to measure  AC line voltage.    There were no reviews I could find that were in English so I thought I would run one.   I agree, it is very complex for what it does.   

I have updated the spreadsheet to include the UT15C.  No other changes were made.   

[ehuesman]

Hi Joe,

Your videos and this thread have been extremely helpful in my decision making about buying a budget multi-purpose multimeter, so thank you very much for the work you put in. I've posted my own thread concerning a couple models I've narrowed it down to, based in large part on your information. My question here has to do with your spreadsheet attached to this thread. Is there a way to annotate or color-code the headings so that I know the CAT rating each test applies to? Meaning, if one of the tests was "3.0KV 2 ohm", which CAT protection level would that fall under? I can look at the spreadsheet now and see where certain models failed, but I can't tell if the failure was before or after their supposed CAT rating (unless I'm missing something, which is totally possible, and in that case I apologize).

I'm specifically interested in the two Amprobe models and the Greenlee model you tested. The AM-510 and AM-530 are both supposed to be CAT III and the DM-20 was labeled a CAT II.

Thanks in advance!

- Eric

[joeqsmith]

Hi Joe,

Your videos and this thread have been extremely helpful in my decision making about buying a budget multi-purpose multimeter, so thank you very much for the work you put in. I've posted my own thread concerning a couple models I've narrowed it down to, based in large part on your information. My question here has to do with your spreadsheet attached to this thread. Is there a way to annotate or color-code the headings so that I know the CAT rating each test applies to? Meaning, if one of the tests was "3.0KV 2 ohm", which CAT protection level would that fall under? I can look at the spreadsheet now and see where certain models failed, but I can't tell if the failure was before or after their supposed CAT rating (unless I'm missing something, which is totally possible, and in that case I apologize).

I'm specifically interested in the two Amprobe models and the Greenlee model you tested. The AM-510 and AM-530 are both supposed to be CAT III and the DM-20 was labeled a CAT II.

Thanks in advance!

- Eric

Eric,  I'm glad you found the videos helpful.   Yes, I can easily color code the spreadsheet to show the CAT rating each test applies to.   In every case, THEY DON'T!!      
There are two big differences.   Because IEC is concerned with safety and I am only concerned with robustness, the meters NEVER see the energy levels they could if tested to the IEC standard.      The real generators will meet both the open and short circuit waveform requirements.   I limit the shorted energy to less than 20 Joules. 

For tests below 6KV, I now test with a open circuit, 100us FWHH.   6KV and above are now ran with a 50us FWHH, more like the IEC standard.     

Now........  Consider if the meter would not break over and had a 10M input.  It will not matter what the short circuit waveform looks like.    It's hard to push a few thousand amps through an open.    This is only going to come into play when something goes wrong.

I have not been buying meters that are lower than CAT III.   So I always test with a 2 ohm source now.   

For the 2nd edition of the standard, CAT III & IV 1.2/50us open waveform peaks are:
CAT III 50, 800 V peak
CAT III 100, 1500 V peak
CAT III 150, 2500 V peak
CAT III 300, 4000 V peak
CAT III 600, 6000 V peak
CAT III 1000, 8000 V peak
 
CAT IV 50, 1500 V peak
CAT IV 100, 2500 V peak
CAT IV 150, 4000 V peak
CAT IV 300, 6000 V peak
CAT IV 600, 8000 V peak
CAT IV 1000, 12000 V peak

A meter that is rated to CAT III 1000 does not mean it is also rated to CAT IV 600!!!!   So don't read more into this than what it is!

Obviously, I have been playing around with some higher energy levels but nothing that has been added to the spreadsheet and even then, these energy levels are still far below what we would test for with the IEC standards.   

Hope this helps.


   

[ehuesman]

I'm sure your answer would be helpful if I had the slightest clue as to what you were talking about, lol. I should've paid more attention to what you were saying in your videos. Based on some of your remarks and the title of the thread, I made the assumption (I know...) you were checking the multimeters against their claimed safety standard. I don't understand what you just told me, but I do understand my assumption was wrong. 

Either way, your testing was still a good guide for me and definitely was crucial in my decision to only go with independently tested models, so thank you.