Poll

Are you interested in seeing more handheld meters tested?

This testing is pointless! Please STOP damaging these meters!
3 (6.4%)
 Yes, I would like to more meters tested.
44 (93.6%)

Total Members Voted: 47

Author Topic: Handheld meter robustness testing  (Read 647717 times)

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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #750 on: March 08, 2016, 11:28:07 pm »
Measure down to 10A...?  :-//

Maybe down was correct and the "0" was supposed to be an "m"?   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #751 on: March 10, 2016, 06:33:04 pm »
The Hioki DT4252 part 2.

How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline RobertoLG

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Re: Handheld meter electrical robustness testing.
« Reply #752 on: March 10, 2016, 11:05:02 pm »
tuff meter, huh?   :-+
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #753 on: March 10, 2016, 11:22:44 pm »
tuff meter, huh?   :-+

If it had just a small amount more plastic in that guard I would not be surprised if I could not damage it.   

I have updated the spreadsheet for those interested.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline RobertoLG

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Re: Handheld meter electrical robustness testing.
« Reply #754 on: March 10, 2016, 11:46:42 pm »
tuff meter, huh?   :-+

If it had just a small amount more plastic in that guard I would not be surprised if I could not damage it.   

I have updated the spreadsheet for those interested.

hehe, I really would like to have one of these...but heh "just dreams" nevermind

and thanks for the nice testing videos  :-+
 

Offline quarks

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Re: Handheld meter electrical robustness testing.
« Reply #755 on: March 11, 2016, 01:46:47 am »
Great work and very informative :-+ :-+ :-+
 

Offline saturation

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Re: Handheld meter electrical robustness testing.
« Reply #756 on: March 13, 2016, 04:59:21 pm »
Great work, Joe, as always on this entire series.

Hioki builds great devices, but this Hioki DMM series continues to have 2 shortcomings. 

First, the creepage distances are a bit close [ as Joe points out too] in other areas.

https://www.eevblog.com/forum/testgear/new-hioki-multimeer-and-first-project/msg736814/#msg736814

Why is there no NRTL safety rating beyond CE or KCC [ the are not recognized in the USA by OSHA ]?  It may be because of what Joe shows.

From the slow motion, where the creepages are too close, added areas of arcing occur. If all the arcing is stopped by the plastic spacer it would be best to reshoot the video showing no added arcing occurs. 

The basic Hioki design out of box however, has a fault, and it allows arcs to propagate despite the GDT input protection at the 8kV impulse, which is the CAT III, 600V rating.

You can see the GDT glowing in the videos.  the GDT is simply not fast enough for this application.

http://blog.circuitprotection.com/communications/movs-vs-gdts-which-one-do-i-use/

It would be better to use both the MOV and GDT at the inputs or MOV alone.  The GDT acts to prolong the life of the MOVs particularly in high energy overvoltage.

Recall, this is a test impulse.  The real world worse case is that the impulse rides atop high energy AC, such as line voltage, and if the arcing occurs, it provides the pathway for an arc blast.

In this screen grab, one arc extended around the plastic shield from V+ terminal.  Another extends from the center GND terminal from one of end of the fuse and from the fuse end to the ground plane.  You can also see the GDT glowing.



In this grab, the corona post arcing lights up the fault areas.


The meter surviving the arc is a good thing, but that could be because so much energy is shunted across the inputs nothing appears to the more high impedance DMM circuitry.

However, the point of the protective devices is to protect the user first, not the DMM, for the specific CAT rating of the meter.




The Hioki DT4252 part 2.


« Last Edit: March 13, 2016, 05:20:18 pm by saturation »
Best Wishes,

 Saturation
 

Offline mos6502

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Re: Handheld meter electrical robustness testing.
« Reply #757 on: March 13, 2016, 07:11:19 pm »
However, the point of the protective devices is to protect the user first, not the DMM, for the specific CAT rating of the meter.

Well, that's a bit of a flaw in this entire test series. It's like doing crash tests with cars, and then concluding that the car that deformed the least must be the best one, without considering what would have happened to the occupants.
for(;;);
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #758 on: March 14, 2016, 12:57:42 am »

From the slow motion, where the creepages are too close, added areas of arcing occur. If all the arcing is stopped by the plastic spacer it would be best to reshoot the video showing no added arcing occurs. 

It would be better to use both the MOV and GDT at the inputs or MOV alone.  The GDT acts to prolong the life of the MOVs particularly in high energy overvoltage.

Recall, this is a test impulse.  The real world worse case is that the impulse rides atop high energy AC, such as line voltage, and if the arcing occurs, it provides the pathway for an arc blast.

In this screen grab, one arc extended around the plastic shield from V+ terminal.  Another extends from the center GND terminal from one of end of the fuse and from the fuse end to the ground plane.  You can also see the GDT glowing.

The meter surviving the arc is a good thing, but that could be because so much energy is shunted across the inputs nothing appears to the more high impedance DMM circuitry.


If you like, I can re-shoot the video with the 14KV pulse and the small insert.   

What I mention in the video as being a possible secondary clamp are marked BZ 4CZRV  and BZ 5DGS9.   

You are very much correct, both of these generators are very low energy (less than 20J).  The original generator will output a 50uS FWHH with an open but will not meet the IEC current waveform.  For reason!! 


However, the point of the protective devices is to protect the user first, not the DMM, for the specific CAT rating of the meter.

Well, that's a bit of a flaw in this entire test series. It's like doing crash tests with cars, and then concluding that the car that deformed the least must be the best one, without considering what would have happened to the occupants.

Car crash testing infers safety, which again is not what these tests have ever been about.   Of course the internet is filled with people who will never figure this out. 


How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #759 on: March 14, 2016, 01:29:18 am »
Guessing it is a BZ series TVS from Littlefuse.  Very fast...

You pointed out how it arcs without the fuse on the right.  If I rerun the meter, would you like the fuse in place (which should prevent that arc)?     
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #760 on: March 15, 2016, 02:58:36 am »
Guessing it is a BZ series TVS from Littlefuse.  Very fast...

You pointed out how it arcs without the fuse on the right.  If I rerun the meter, would you like the fuse in place (which should prevent that arc)?   

I looked up the parts I suspected were TVSs.  Looks like the BZ is the part and the rest is the date code.  The BZ is a SMAJ24A or SMBJ24A,  400W unidirectional TVS.  Switching time will be very fast on these.  Once the GDT fires, it should dissipate most of the energy.   



How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #761 on: March 15, 2016, 03:04:53 am »
I took a few pictures of the second breakdown that was pointed out.   In this first picture, the red line shows the path, starting with the input, across the slit (note the plastic insert from testing), to the fuse holder.  Because there was no fuse installed, it was going to go between the common and Amp connectors or instead it jumped to the right side of the fuse holder and followed its way back to the common.
 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #762 on: March 15, 2016, 03:27:14 am »
In these two pictures we can see where the arc took place.  The blue is where I touched it with the ink pen during the video.   Again, had the fuse been in place, it would have just jumped at the one side (with this generator).   

What makes it unique is normally once a meter arcs, they will fail functionally as I increase the levels. In most cases the meters are not repairable.   I would guess in many cases there is some form of arc that happens before the meters become nonfunctional.  I may not always hear it or see it on the DSO.   

Some meters like the Flukes, Brymen, AMPROBEs, there has been enough additional protection circuitry that it has saved the control IC and I have been able to repair them to some degree (less PCB damage).     In the case of the Hioki, we have a meter that requires about 10KV to arc across a controlled gap and no damage to any of the electronics.   

How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #763 on: March 15, 2016, 04:03:22 am »
Closer view of area
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #764 on: March 16, 2016, 02:00:51 am »
However, the point of the protective devices is to protect the user first, not the DMM, for the specific CAT rating of the meter.

I would guess that most of the safety in hand held meters comes from the mechanics.   Things like spacing, wall thickness, double walled, etc.  Things like the GDTs, MOVs, secondary clamps, PTCs are there to protect the meter so it does not need to be replaced or repaired.   Maybe have a look at patents 5396168, 5606481, 5920188
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #765 on: March 20, 2016, 02:32:53 am »


How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
The following users thanked this post: saturation

Offline RobertoLG

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Re: Handheld meter electrical robustness testing.
« Reply #766 on: March 20, 2016, 03:08:05 am »
nice meter  :-+
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #767 on: March 21, 2016, 02:19:47 am »
nice meter  :-+

I don't like how the Hioki has an error when there is a large offset in an AC signal.  Not a fan of the display or back light on it.   

I was looking at the Digitek DT-2843R you asked about.  5ky had sent me a TekPower TP2844R.   The circuit boards for the two meters are very similar.  There is a placeholder for the MOV on the TekPower but it was not populated.   The Digitek PCB is marked K10062843R,  the TekPower is K10052844R.   It may do better with the MOV installed across the inputs with my tests but it seems like a bad idea.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline RobertoLG

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Re: Handheld meter electrical robustness testing.
« Reply #768 on: March 21, 2016, 02:54:10 am »
nice meter  :-+

I don't like how the Hioki has an error when there is a large offset in an AC signal.  Not a fan of the display or back light on it.   

I was looking at the Digitek DT-2843R you asked about.  5ky had sent me a TekPower TP2844R.   The circuit boards for the two meters are very similar.  There is a placeholder for the MOV on the TekPower but it was not populated.   The Digitek PCB is marked K10062843R,  the TekPower is K10052844R.   It may do better with the MOV installed across the inputs with my tests but it seems like a bad idea.

thank you for taking a look into it, I saw your video testing it, and from that other guy too, I just wanted to know more clearly how it would do with some harder testing, and yeah better be careful.
and about the hioki, I liked it, it's a very robust meter, that can handle some bad stuff very well, I would buy one without doubt if I could, did a search just for curiosity, but they don't sell them here in brazil, I found a rebranded brymen, but the price is ridiculous, I think it's the same model that Dave is selling, maybe in the future I get something better if I can.
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #769 on: March 22, 2016, 02:25:04 am »
nice meter  :-+

I don't like how the Hioki has an error when there is a large offset in an AC signal.  Not a fan of the display or back light on it.   

I was looking at the Digitek DT-2843R you asked about.  5ky had sent me a TekPower TP2844R.   The circuit boards for the two meters are very similar.  There is a placeholder for the MOV on the TekPower but it was not populated.   The Digitek PCB is marked K10062843R,  the TekPower is K10052844R.   It may do better with the MOV installed across the inputs with my tests but it seems like a bad idea.

thank you for taking a look into it, I saw your video testing it, and from that other guy too, I just wanted to know more clearly how it would do with some harder testing, and yeah better be careful.
and about the hioki, I liked it, it's a very robust meter, that can handle some bad stuff very well, I would buy one without doubt if I could, did a search just for curiosity, but they don't sell them here in brazil, I found a rebranded brymen, but the price is ridiculous, I think it's the same model that Dave is selling, maybe in the future I get something better if I can.

This would be the one time it would be fun to run it with the included probes on a real generator rather than my toy setup.  It would not tell you anything about how it compares with the other meters but we could get a pretty good idea about safety.  If I remember, next order I'll see if Digikey stocks the MOVs and get a few.  Maybe just hook one across my toy generator and get some good high speed footage from it.   

I had seen a video where someone was showing a bunch of pocket meters.   They did not take them apart or try to stress them.  I may pick up a few low end ones and see how they look. 
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline RobertoLG

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Re: Handheld meter electrical robustness testing.
« Reply #770 on: March 22, 2016, 03:39:23 am »
if you get some pocket meters, let us see how they are, I'm curious too
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #771 on: March 22, 2016, 01:08:34 pm »
Not a problem.  I ordered a few of them.  Maybe in a couple of weeks I'll have some time to start checking them.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #772 on: March 26, 2016, 02:30:11 am »
Attempt to test an MOV directly connected to my generator.   

How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline RobertoLG

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Re: Handheld meter electrical robustness testing.
« Reply #773 on: March 26, 2016, 02:54:10 am »
 you are the one who likes the firecrackers  :-DD , I'm curious how the pocket meters will do, or how many will just pop, and thanks for taking the time to test with the MOV  :-+
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #774 on: March 26, 2016, 03:17:23 am »
you are the one who likes the firecrackers  :-DD , I'm curious how the pocket meters will do, or how many will just pop, and thanks for taking the time to test with the MOV  :-+

 :-DD I just could not leave the video ending with not being able to run the test.  Dave had made a recent video showing his new high speed camera.  He had attempted to blow a few caps without success.   I figured, may as well show the same thing.  Then I forgot to arm the camera on the first cap.   |O  These cameras are pretty good for the price but they are just not fast enough.   

I had actually ordered a few MOVs that are very close to what is used in the Digitek.  This was before I attempted to test the smaller part.  Sorry it did not work out but I am still thinking that putting all of this current through the leads and meter is not good.

Looking at the UT20, it is marked CAT II 300V.  Without even seeing the other ones I ordered, I can pretty much guess that none of them will hold to the levels 5ky's Fluke 107 did.  :-DD     

I plan to spend some time looking at that UT210E first.   

How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 


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