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 electrical robustness testing.  (Read 516386 times)

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Offline jordanp123

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Re: Handheld meter electrical robustness testing.
« Reply #2400 on: March 04, 2018, 01:38:40 am »
Has anyone torn apart/tested one of the new AMES meters from Harbor freight ? Saw them today and they looked decent for an electricians meter, had a ETL listing as well.
 

Offline rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #2401 on: March 04, 2018, 04:17:47 am »
MOVs would give up if limiar overvoltage is applied for too long - the circuitry could probably withstand 1.1~1.2kV, but the MOVs would suffer thermal stress. All in all, I don't think any meter would be too different in this regard (unless they used higher voltage MOVs).
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2402 on: March 04, 2018, 05:07:30 am »
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Online Fungus

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Re: Handheld meter electrical robustness testing.
« Reply #2403 on: March 04, 2018, 11:19:47 am »
Exactly what I was thinking.  Can it really be this bad?   I was going to run the tests just for completeness but now I wonder if it is not even going to make it to the transient tests.

You could try it on your old, repaired one. That way nobody can accuse you of not using a pristine meter in the 'real' tests.

(are we really debating which test do do first because we're worried it might not survive any of them?)
 

Offline rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #2404 on: March 04, 2018, 12:54:40 pm »
MOVs would give up if limiar overvoltage is applied for too long - the circuitry could probably withstand 1.1~1.2kV, but the MOVs would suffer thermal stress. All in all, I don't think any meter would be too different in this regard (unless they used higher voltage MOVs).

I've had people suggest similar things but it really makes no sense to me.  Maybe you could explain why you feel this way.  What is causing all of this thermal stress you mention?
If a MOV rated (loose definition of "rated" here) for 1kV is subjected to, say, 1.2kV, it will try to clamp this voltage differential using the only means it knows: by dissipating the surplus energy through its body. But that you already know.

In the scenario above, considering the output impedance of the source is low enough, the amount of the surplus energy that needs to be dissipated depends on the waveform. In a single pulse transient, the extra energy is perfectly contained with minor (if at all) stress to the MOV. On the other hand, a 1.2kVAC at 50 or 60 Hz will demand the MOV to continuously dissipate the energy contained in the upper and lower cycles of the sinewave. By the same logic and what was reported in the thread I mentioned, 1.2kVDC is the worst scenario as there is no time for the MOV to cool.

In the AC scenario (and to a much lesser extent to DC), the survivabilty of the MOV is highly dependent on its physical characteristics, as well as its environmental (temperature and humidity) and the surrounding heatsink ability of its PCB (large copper areas, clearance, etc.). That is why I mentioned that most (if not all) DMMs would have the same outcome as reported in the linked thread.
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline WhichEnt2

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Re: Handheld meter electrical robustness testing.
« Reply #2405 on: March 04, 2018, 01:27:22 pm »
They are changed 2 smd caps above the "fluke and linear" branded IC. On your video small caps are installed, but on early teardown photos they use big caps.
In my 87V which is manufactured at feb 2017 they are also small.



Short pieces, high value, small period, huge amount, long delay.
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2406 on: March 04, 2018, 02:37:03 pm »
MOVs would give up if limiar overvoltage is applied for too long - the circuitry could probably withstand 1.1~1.2kV, but the MOVs would suffer thermal stress. All in all, I don't think any meter would be too different in this regard (unless they used higher voltage MOVs).

I've had people suggest similar things but it really makes no sense to me.  Maybe you could explain why you feel this way.  What is causing all of this thermal stress you mention?
If a MOV rated (loose definition of "rated" here) for 1kV is subjected to, say, 1.2kV, it will try to clamp this voltage differential using the only means it knows: by dissipating the surplus energy through its body. But that you already know.

In the scenario above, considering the output impedance of the source is low enough, the amount of the surplus energy that needs to be dissipated depends on the waveform. In a single pulse transient, the extra energy is perfectly contained with minor (if at all) stress to the MOV. On the other hand, a 1.2kVAC at 50 or 60 Hz will demand the MOV to continuously dissipate the energy contained in the upper and lower cycles of the sinewave. By the same logic and what was reported in the thread I mentioned, 1.2kVDC is the worst scenario as there is no time for the MOV to cool.

In the AC scenario (and to a much lesser extent to DC), the survivabilty of the MOV is highly dependent on its physical characteristics, as well as its environmental (temperature and humidity) and the surrounding heatsink ability of its PCB (large copper areas, clearance, etc.). That is why I mentioned that most (if not all) DMMs would have the same outcome as reported in the linked thread.
Because I am currently looking at the 87V,  let's just use it for an example.  A few things to consider.  The one MOV has a 1Meg resistor in series with it.  Even with 2KV applied, will limit the current to 2mA assuming the MOVs were shorted.    The second leg uses a PTC and surge rated resistor for the drive side.  With enough DC the PTC would eventually kick in but may not limit the current enough to prevent long term damage (assuming the secondary clamp is not engaged).    However...   

I think the standards require 1.1 times the meter's rating but I would need to double check that.  In any case the F87V uses S05K575 MOVs.  These have a 785VDC rating.   You have two in series.  So even if the voltage is at 1.5KVDC, the MOVs are not doing much of anything.  I've looked at a fair number of meters now.  Granted, there is some cheap junk out there but let's ignore that class.  For the meters rated for 1KV, looking over my note,  I don't see any that clamp a couple hundred over 1KV.   One meter was sort of a hybrid using a combination of GDTs and a MOV.   The MOV in this case had a DC rating of 670 volts.  However, the GDTs would not fire until 1200.  With a DC source, if you did manage to trip the GDTs they are going to stay on until the current drops which would put a strain on the MOV.  But again, we have to get he GDT to turn on in the first place.   

Obviously if the voltage was so high that the MOVs were conducting and we left it like this for an extended time, I fully agree that the MOV will degrade but I just don't see this happening at the sub 1.5KV. 

Assuming there is anything left of the 87V when I am done with it, I would be willing to attach it to a 1.2KVDC power supply and let it sit for a long term test.  Say a week with the meter in the DC volts setting.   
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #2407 on: March 04, 2018, 03:41:56 pm »
MOVs would give up if limiar overvoltage is applied for too long - the circuitry could probably withstand 1.1~1.2kV, but the MOVs would suffer thermal stress. All in all, I don't think any meter would be too different in this regard (unless they used higher voltage MOVs).

I've had people suggest similar things but it really makes no sense to me.  Maybe you could explain why you feel this way.  What is causing all of this thermal stress you mention?
If a MOV rated (loose definition of "rated" here) for 1kV is subjected to, say, 1.2kV, it will try to clamp this voltage differential using the only means it knows: by dissipating the surplus energy through its body. But that you already know.

In the scenario above, considering the output impedance of the source is low enough, the amount of the surplus energy that needs to be dissipated depends on the waveform. In a single pulse transient, the extra energy is perfectly contained with minor (if at all) stress to the MOV. On the other hand, a 1.2kVAC at 50 or 60 Hz will demand the MOV to continuously dissipate the energy contained in the upper and lower cycles of the sinewave. By the same logic and what was reported in the thread I mentioned, 1.2kVDC is the worst scenario as there is no time for the MOV to cool.

In the AC scenario (and to a much lesser extent to DC), the survivabilty of the MOV is highly dependent on its physical characteristics, as well as its environmental (temperature and humidity) and the surrounding heatsink ability of its PCB (large copper areas, clearance, etc.). That is why I mentioned that most (if not all) DMMs would have the same outcome as reported in the linked thread.
Because I am currently looking at the 87V,  let's just use it for an example.  A few things to consider.  The one MOV has a 1Meg resistor in series with it.  Even with 2KV applied, will limit the current to 2mA assuming the MOVs were shorted.    The second leg uses a PTC and surge rated resistor for the drive side. With enough DC the PTC would eventually kick in but may not limit the current enough to prevent long term damage (assuming the secondary clamp is not engaged).    However...   
That sums it up. I should have prefaced my post with the assumption the MOVs are directly in parallel with the inputs - in other words, I was completely illiterate about the 87V's input circuitry. :)

Assuming there is anything left of the 87V when I am done with it, I would be willing to attach it to a 1.2KVDC power supply and let it sit for a long term test.  Say a week with the meter in the DC volts setting.   
That would be an interesting test.
Vbe - vídeo blog eletrônico http://videos.vbeletronico.com

Oh, the "whys" of the datasheets... The information is there not to be an axiomatic truth, but instead each speck of data must be slowly inhaled while carefully performing a deep search inside oneself to find the true metaphysical sense...
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2408 on: March 04, 2018, 04:15:34 pm »
That sums it up. I should have prefaced my post with the assumption the MOVs are directly in parallel with the inputs - in other words, I was completely illiterate about the 87V's input circuitry. :)

I saw a meter with a place holder for a MOV right across the inputs. I think it may have been sold by Tek Power.  The MOV was not populated for good reason.   Imagine the stress that would put on the leads, PCB, MOV....   If anyone ever comes across a handheld meter that uses a MOV without any additional limiting device/s, please let me know.

Assuming there is anything left of the 87V when I am done with it, I would be willing to attach it to a 1.2KVDC power supply and let it sit for a long term test.  Say a week with the meter in the DC volts setting.   
That would be an interesting test.
Consider it done.  I will need to set up some sort of containment so the inquisitive critters are kept safe.   Maybe measure the input impedance before and after the test.  Let me think about it.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline HKJ

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Re: Handheld meter electrical robustness testing.
« Reply #2409 on: March 04, 2018, 04:19:24 pm »
If anyone ever comes across a handheld meter that uses a MOV without any additional limiting device/s, please let me know.

I have seen a spark gab across the input terminals, but I do not remember what meter it was.
 

Offline HKJ

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Re: Handheld meter electrical robustness testing.
« Reply #2410 on: March 04, 2018, 05:05:38 pm »
I am VERY interested in knowing what meter this is. 

It was a cheap meter with the usually bogus CAT rating:



My review: http://lygte-info.dk/review/DMMPeakmeter%20MS8248S%20UK.html
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2411 on: March 04, 2018, 05:20:31 pm »
Speechless
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Offline Cliff Matthews

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Re: Handheld meter electrical robustness testing.
« Reply #2412 on: March 04, 2018, 06:18:20 pm »
No shunt? er.. maybe it's the fuse..  :-DD  I've seen nube's everywhere raving on any product that gets rid of that "nasty range switch"
 

Offline Hydrawerk

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Re: Handheld meter electrical robustness testing.
« Reply #2413 on: March 04, 2018, 10:14:39 pm »
OK, Fluke 87V is not a very good product. What about Fluke 289, 28II or 179??
Amazing machines. https://www.youtube.com/user/denha (It is not me...)
 

Online Fungus

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Re: Handheld meter electrical robustness testing.
« Reply #2414 on: March 05, 2018, 04:28:15 am »
OK, Fluke 87V is not a very good product. What about Fluke 289, 28II or 179??

Does this look like a multimeter shootout thread or a "Which multimeter should I buy?" thread?  :-//

The 87V is supposedly the yardstick meter, the industry standard for excellence, the meter that can do no wrong.

So far joe's only unboxed it and noted a clunky user interface (how many secret power-on modes does it have?) and cheap fit and finish (poor plastics, bent shield).

Testing's not over yet. Not by a long way.
« Last Edit: March 05, 2018, 04:48:49 am by Fungus »
 

Offline tautech

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Re: Handheld meter electrical robustness testing.
« Reply #2415 on: March 05, 2018, 05:00:46 am »
OK, Fluke 87V is not a very good product. What about Fluke 289, 28II or 179??

Does this look like a multimeter shootout thread or a "Which multimeter should I buy?" thread?  :-//

The 87V is supposedly the yardstick meter, the industry standard for excellence, the meter that can do no wrong.

So far joe's only unboxed it and noted a clunky user interface (how many secret power-on modes does it have?) and cheap fit and finish (poor plastics, bent shield).

Testing's not over yet. Not by a long way.
Yeah right !
You're new here aren't you ?

Tucked way back on P13 of this 100 pages of goodness:
https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg708183/#msg708183

2 1/2 years ago !
Avid Rabid Hobbyist
 

Online Fungus

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Re: Handheld meter electrical robustness testing.
« Reply #2416 on: March 05, 2018, 05:23:44 am »
The 87V is supposedly the yardstick meter, the industry standard for excellence, the meter that can do no wrong.
Yeah right !
You're new here aren't you ?

Tucked way back on P13 of this 100 pages of goodness:
https://www.eevblog.com/forum/testgear/hear-kitty-kitty-kitty-nope-not-that-kind-of-cat/msg708183/#msg708183

Please pay attention.

There's a whole bunch of people who believe the Fluke 87V is perfect in every way, they insist the previous tests must have been done with faulty meters (or something).

The clue is at the top of the page you're reading:

« Last Edit: March 05, 2018, 07:14:56 am by Fungus »
 

Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2417 on: March 05, 2018, 01:35:22 pm »
Funny, that poll was a fair amount of time ago as well.   Yes, I have read several comments where people felt something was wrong.  Indeed, it may have been.  That's partly why I am doing this series in smaller chunks as well.  It gives people time to digest what is going on and ask questions. 

I still need to run the continuity tests and make sure I don't see any susceptible sweet spots.   Then it's onto more destructive testing.  My plan for the next part is to run the tests in the following order:

open fuse test
AC line
piezo grill starter
ESD gun
transient test to failure (if it can be repaired, I will go ahead and do that)
rotary switch cycle testing
long term 1.2KVDC for rsjsouza
Fungus like the drop tests so I may drop this thing on the block of wood as well

Again, all of this could change depending how the testing goes....
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 
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Offline Muttley Snickers

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Re: Handheld meter electrical robustness testing.
« Reply #2418 on: March 05, 2018, 02:34:33 pm »
Depending on the order you might be able to put Flukes warranty to the test at the same time.   :o :-BROKE
 

Offline ChrisLX200

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Re: Handheld meter electrical robustness testing.
« Reply #2419 on: March 05, 2018, 02:57:08 pm »
Funny, that poll was a fair amount of time ago as well.   Yes, I have read several comments where people felt something was wrong.  Indeed, it may have been.  That's partly why I am doing this series in smaller chunks as well.  It gives people time to digest what is going on and ask questions. 

I still need to run the continuity tests and make sure I don't see any susceptible sweet spots.   Then it's onto more destructive testing.  My plan for the next part is to run the tests in the following order:

open fuse test
AC line
piezo grill starter
ESD gun
transient test to failure (if it can be repaired, I will go ahead and do that)
rotary switch cycle testing
long term 1.2KVDC for rsjsouza
Fungus like the drop tests so I may drop this thing on the block of wood as well

Again, all of this could change depending how the testing goes....

You forgot the flame-thrower test, and maybe Truck test (run it over with your car and see if it still works) :)
 

Offline 3db

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Re: Handheld meter electrical robustness testing.
« Reply #2420 on: March 05, 2018, 11:17:40 pm »
I'm sure Joe has a few guns too.  >:D
 

Offline tautech

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Re: Handheld meter electrical robustness testing.
« Reply #2421 on: March 06, 2018, 01:12:57 am »
I'm sure Joe has a few guns too.  >:D

I could shoot it with my fuse powered cork gun.    :-DD
Piezo ignitor and Methanol upgrade required ?
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Offline joeqsmith

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Re: Handheld meter electrical robustness testing.
« Reply #2422 on: March 06, 2018, 10:52:23 am »
After seeing the bent shield in my brand new Fluke 87V, a member with a slightly older 87V took theirs apart and provided me with this picture.  I had hoped the meter I received was a one off mistake but it appears they are bending the shield and no one is catching it.  I have not yet done anymore with the 87V and it's still sitting in parts.  The shield looks like it is designed to sit flat.  I can place it flat in the board.   The two tabs seem to be setup correctly.    Maybe they cut their QC staff to make more money?  Maybe it's supposed to be bent?   

Too bad these large companies have no presence in these groups.   If it were Brymen, I would just ask them and based on all my previous experiences with them, would have an answer in a day.  I never found a contact at Danaher/Fluke.
How electrically robust is your meter?? https://www.youtube.com/channel/UCsK99WXk9VhcghnAauTBsbg
 

Online Fungus

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Re: Handheld meter electrical robustness testing.
« Reply #2423 on: March 06, 2018, 12:09:20 pm »
Maybe it's deliberate.

Does it press against the back of the case like a spring? Does it look like there's any reason to do that?

I can place it flat in the board.

Doesn't necessarily mean it's supposed to be like that.
 

Online Fungus

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Re: Handheld meter electrical robustness testing.
« Reply #2424 on: March 06, 2018, 12:14:16 pm »
Dave's running a live switch cycle on his second channel.  I watched it for a few minutes.  Tried to calculate the resistance with the formulas shown but looks like its 1.7K ohms the one way  a little better the other.  Guessing I am missing something as I think he said they could only read up to 10 ohms or so.   So much computing power and they resort to sticky notes.   :palm:

He also cleaned off the accumulated dust/debris after every bunch of cycles.  :scared:

If that's fiberglass dust then it's an abrasive, just sayin'.
 


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