Poll

How many cycles will the KeySight U1281A's detent spring last?

0-2000
7 (16.3%)
2k-4k
5 (11.6%)
4k-8k
16 (37.2%)
8k-16k
8 (18.6%)
>16k (most rubust meter ever made)
7 (16.3%)

Total Members Voted: 40

Author Topic: Handheld meter robustness testing  (Read 1218574 times)

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Offline EEVblog

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Re: Handheld meter robustness testing
« Reply #4125 on: September 27, 2021, 04:51:15 am »
No, you just don't get it.  I don't compare or equate my expertise or observations with "entire teams of electronics engineers that do testing day in, day out with special-purpose equipment in dedicated labs", in fact I like working on and repairing equipment designed by such people because I can admire and learn from their efforts. However, I don't confuse high-quality products made by such companies with rubbish hacked together on a shoestring by third rate hacks.

Do you learn nothing from people who are asked to make a full size multimeter at a $25 price point?

If anything, it's more difficult then working on a massive budget to make a "high quality" meter.

Quote
As long as we are making broad statements, I'm curious to know your opinion which is safer, a Chinese product certified by Intertek or a self certified Japanese product?
I'm not playing your game, sorry.
There's no way I would touch that one but I thought you may take a swing at it.  :-DD

Yep. Anbody that frames this as "China vs. Japan" instead of "Uni-T vs. Hioki" is at the Donald Trump level of debate.

Problem is the vast majority of cheap meters come out of China, that's just a fact. Literally hundreds of different models all built down to a price.
Is there any "no name" cheap meter manufacturer in Japan? I'd assume there would have to be, but off-hand I can't remember seeing one. Sanwa, Hioki and Kyoritsu are the only names that spring to mind, and all are reputable makers of top tier pricing industrial meters.
 

Offline bdunham7

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Re: Handheld meter robustness testing
« Reply #4126 on: September 27, 2021, 05:06:29 am »
Do you learn nothing from people who are asked to make a full size multimeter at a $25 price point?

If anything, it's more difficult then working on a massive budget to make a "high quality" meter.

It is true that ingenuity can often be found in simplicity, but I rarely find it as appealing when it involves cost-cutting beyond a certain point.  Shortcuts get taken and stuff gets left out.  I've dealt with cost-cutting in many situations (not multimeters) and in my experience the people looking to achieve that goal make it difficult for everyone else more than they do for themselves.   So yes, I learn nothing from them because even if they know something, it's not knowledge that I want or need anymore than I need to learn how to make a stew from a roadkill possum and a pair of old shoes.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4127 on: September 27, 2021, 10:44:27 am »
As long as I am thinking about it, a member had asked about connecting the UT61E+ to the 220V mains with it set to the resistance mode.   I had checked your review and you did not run that test.  Because I had already damaged the one I bought, any way to talk you into running it with yours?

Left on for 10 seconds, survives just fine at the nominal 245V here. Readings a smidge low as the PTC recovers.

Thanks.  I tried running mine 300VACRMS 60Hz and it also survived.   

Online joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4128 on: September 27, 2021, 11:01:45 am »
When I was a child I had some small toys that came from Japan.  We would call them gypan as the toys would fall apart after a short use.   I would imagine that Tachikawa meter I looked at was very cheap for the time.   Even today, I'm not impressed with the display used on the YOKOGAWA TY720. 

Offline Muttley Snickers

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Re: Handheld meter robustness testing
« Reply #4129 on: September 27, 2021, 11:35:49 am »
This morning I accidentally destroyed a multimeter which had served me well for over twenty five years so I'm not happy about it and feel like I've lost a dear friend.   :-BROKE :(

I couldn't get the lawn mower started and after checking everything else I found the throttle controlled kill switch had an intermittent short to the chassis which explained why the mower would run for a few seconds and then cut out.

The meter copped a whack from the magneto whilst in resistance mode and is now completely buggered. Out of curiosity I repeated the same scenario with a Fluke 83 without any problems. The damaged meter was a Dick Smith Q1425 and has a 40 pin ICL7106CPL dated 10/94 so almost 27 years old but in immaculate condition for its age.

Edit: Image to follow soon. 
« Last Edit: September 29, 2021, 01:02:10 pm by Muttley Snickers »
 

Offline Muttley Snickers

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Re: Handheld meter robustness testing
« Reply #4130 on: September 27, 2021, 12:04:40 pm »
It wasn't anything special meter wise and they are a dime a dozen nowadays, back then they were around $20. Also, there are already enough threads and information around on these and similar meters so I didn't feel it warranted a new thread.

 

Offline Kean

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Re: Handheld meter robustness testing
« Reply #4131 on: September 27, 2021, 12:14:51 pm »
The damaged meter was a Dick Smith Q1425 and has a 40 pin ICL7106CPL dated 10/94 so almost 27 years old but in immaculate condition for its age.

Another 10 years or so and it would probably have been manufactured in Japan.
 

Online rsjsouza

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Re: Handheld meter robustness testing
« Reply #4132 on: September 27, 2021, 01:04:21 pm »
As long as I am thinking about it, a member had asked about connecting the UT61E+ to the 220V mains with it set to the resistance mode.   I had checked your review and you did not run that test.  Because I had already damaged the one I bought, any way to talk you into running it with yours?

Left on for 10 seconds, survives just fine at the nominal 245V here. Readings a smidge low as the PTC recovers.

Thanks.  I tried running mine 300VACRMS 60Hz and it also survived.   
I evaluated several meters on my channel and, although I don't apply an untamed outlet-level power supply on them, I use a reduced 80~90V current-limited source to get an idea of a meter's survivability in case of wrong selection by a user - a much more common case of multimeter failure (when compared to transients) among the folks that watch my channel. Even at that ridiculously low level, several meters failed this specific test with weird behaviour such as resetting, powering down, beeping uncontrollably, etc., giving a hint about its survivability.

In my anecdoctal evidence of comments and reports from the audience and direct messaging to me, the UL listed UT139C is the meter that died the most, despite passing my test. It is a very weak sample space which can be easily skewed by popularity and availability, since a Brazilian brand has a fully certified UT139C as well as others that I also tested (which failure rate reporting is nowhere near as bad), but that and my experience with certification and compliance (non-multimeter though) tell me the process is flawed and must be improved. And that is where the cynicism comes from us that touched many of these types of equipment: too many examples of flaws that look like have been solely relied (or heavily influenced) on the cert agency accreditation mark to guide design decisions.

Is it a third party independent testing a better scenario than self-certification or reputation alone? Yes, of course, especially since most people don't understand the technicalities of what they are buying - unfortunately this hasn't been he ideal scenario as time and time again it has been proven it is caveat emptor. That is why youtube and the internet have been acting as a "fourth party" source of information.
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Offline Neutrion

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Re: Handheld meter robustness testing
« Reply #4133 on: September 27, 2021, 01:06:00 pm »
.... If it were, we would all be experts at everything.  ...

We are! 

https://www.harvardmagazine.com/2018/03/death-of-expertise-by-tom-nichols
Well it is OT but because you linked it, I think what he describes there is also a good case for a good general education with a broad spectrum even if most of that knowledge will never be needed for for an employment.
Of course "social" media oppinion bubbles just makes the situation much worse.

   I have had a few people ask me about testing AC line devices which point to just how ignorant some viewers are.  I don't see that changing although I run into it less and less.       


I don't know what the "ignorant" people asked from you, but both general household appliances, and especially the common surge protectors are a very interesting topic with all sensitive elctronics to find in an everage household. And the protection itself is very similar to what you can find in the multimeter.
So though you would of course classify me as ignorant too, but I would be really interested in both how an appliance (can be anything like a modern washing machine control board) behaves just with a 2-3000 V small voltage spike what your generator outputs, what different surge protectors let through, and of course what happens if a surge protector really meets with its thaoretical 30-70Ka rating.
(Yes I know that it is not your generator...)
Possibly a huge amount af goods is getting damaged because of this, even without any serious lightning strike or similar big issue.
« Last Edit: September 27, 2021, 01:09:41 pm by Neutrion »
 

Offline EEVblog

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Re: Handheld meter robustness testing
« Reply #4134 on: September 27, 2021, 01:12:37 pm »
The damaged meter was a Dick Smith Q1425 and has a 40 pin ICL7106CPL dated 10/94 so almost 27 years old but in immaculate condition for its age.
Another 10 years or so and it would probably have been manufactured in Japan.

 
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Offline AndrewBCN

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Re: Handheld meter robustness testing
« Reply #4135 on: September 27, 2021, 02:59:15 pm »
...
Is it a third party independent testing a better scenario than self-certification or reputation alone? Yes, of course, especially since most people don't understand the technicalities of what they are buying
So our views coincide on the matter of independent certification.
- unfortunately this hasn't been he ideal scenario as time and time again it has been proven it is caveat emptor. That is why youtube and the internet have been acting as a "fourth party" source of information.
The problem with relying on information from YouTube or any other form of social media rather than information from independent testing and certification companies is quite obvious to me. If you have to take any information from independent testing and certification companies with a grain of salt, information on social media requires a truckload of skepticism and common sense - and time. Since I don't have much common sense and very little time, I always prefer to rely on information from independent testing and certification companies, however flawed it may prove to be in some cases.

 

Online joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4136 on: September 27, 2021, 03:36:18 pm »
.... If it were, we would all be experts at everything.  ...

We are! 

https://www.harvardmagazine.com/2018/03/death-of-expertise-by-tom-nichols
Well it is OT but because you linked it, I think what he describes there is also a good case for a good general education with a broad spectrum even if most of that knowledge will never be needed for for an employment.
Of course "social" media oppinion bubbles just makes the situation much worse.

I've read his book and recommend it.   

   I have had a few people ask me about testing AC line devices which point to just how ignorant some viewers are.  I don't see that changing although I run into it less and less.       


I don't know what the "ignorant" people asked from you, but both general household appliances, and especially the common surge protectors are a very interesting topic with all sensitive elctronics to find in an everage household. And the protection itself is very similar to what you can find in the multimeter.
So though you would of course classify me as ignorant too, but I would be really interested in both how an appliance (can be anything like a modern washing machine control board) behaves just with a 2-3000 V small voltage spike what your generator outputs, what different surge protectors let through, and of course what happens if a surge protector really meets with its thaoretical 30-70Ka rating.
(Yes I know that it is not your generator...)
Possibly a huge amount af goods is getting damaged because of this, even without any serious lightning strike or similar big issue.

I am not aware of any appliances that use surge rated resistors in series with PTC and then shunted with MOVs, with selectable low voltage clamps made from back to back transistors.    I have had people write me about running my tests too fast and over heating the MOVs in the DMMs. 

People have asked me about running devices which would attach to the mains like power supplies and surge protectors across my generator.  Yes, very ignorant. Sadly, the people who ask I expect lack the basic education to understand even the basics of what has been shown, so I don't see an easy fix.     

Offline AndrewBCN

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Re: Handheld meter robustness testing
« Reply #4137 on: September 27, 2021, 03:41:52 pm »
Another 10 years or so and it would probably have been manufactured in Japan.
"all the best stuff is made in Japan..."

That perception changes with time and marketing and the kind of "stuff" we are talking about. Also the average American has a hard time telling one Asian country apart from another.

For PC motherboards, "all the best stuff is made in Taiwan..."
For LCD/OLED TVs and monitors, "all the best stuff is made in South Korea..."
Of the EEVblog DMMs, I believe two are made in Taiwan and one in South Korea?

And the way things are going, sooner or later, all the popular "best stuff" will be made in China, even if it is sold under a Western or Taiwanese or Japanese brand. Including digital multimeters.
« Last Edit: September 27, 2021, 03:44:22 pm by AndrewBCN »
 

Offline Neutrion

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Re: Handheld meter robustness testing
« Reply #4138 on: September 27, 2021, 04:32:23 pm »


I am not aware of any appliances that use surge rated resistors in series with PTC and then shunted with MOVs, with selectable low voltage clamps made from back to back transistors.    I have had people write me about running my tests too fast and over heating the MOVs in the DMMs. 

People have asked me about running devices which would attach to the mains like power supplies and surge protectors across my generator.  Yes, very ignorant. Sadly, the people who ask I expect lack the basic education to understand even the basics of what has been shown, so I don't see an easy fix.   

I understand that it is not exacly the same setup,but it is similar, by means of trying to clamp down an overvoltage to save a microcontroller, and other sensitive stuff.
Even small energy spikes get through the main lines which damage equipment.
And it is indeed interesting, what different surge protectors can let through from even these small energy spikes.
So if you mean it is ignorance because the small energy involved, than again, you don't necessary have huge surges on the AC line. The waveform of course is different. That is what you mean? But actually... it also does not have to be entirely different...
And with a surge protector it is quiet interesing what they actually let through from these smaller spikes.
1000V? 300V? With what rise time? Same with the named control board: What is a maximal small surge it can handle?

And regarding testing a surge protector with a massive surge, well that though needs a different generator or condensator bank, but again, still an interesting topic, and not many people can or will present it with attached proper measuring equipment.
 






 

Offline bdunham7

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Re: Handheld meter robustness testing
« Reply #4139 on: September 27, 2021, 05:12:11 pm »
The problem with relying on information from YouTube or any other form of social media rather than information from independent testing and certification companies is quite obvious to me. If you have to take any information from independent testing and certification companies with a grain of salt, information on social media requires a truckload of skepticism and common sense - and time. Since I don't have much common sense and very little time, I always prefer to rely on information from independent testing and certification companies, however flawed it may prove to be in some cases.

I certainly agree that the signal-to-noise noise to signal ratio on YouTube, or even EEVBlog can be quite high.  But you make it seem as if there are only two choices--social media or Intertek--and that your decisions somehow need to be made on technical merits.  You say you 'prefer to rely', which to me means 'choose to believe'--a silly concept IMO, but we'll go with it.  I opt to rely on a the technical merit and integrity of companies that have provided excellent products that have served me and others reliably, sometimes under very tough conditions, for decades.  When I see a company that has been producing utter rubbish for those same decades come out with a product that 'competes' at less than 1/10 the price and then hangs a 'certification' on it, I don't need any technical expertise to know to regard those claims as highly suspect.  But still you have those who go for it, perhaps because they can't resist the allure of a cheap deal, and then even go so far as to criticize the reliable, reputable A-brand for not hanging higher ratings on their meters.

I would just let that go as consumer idiocy, except that the rating part just bothers me.  There are people who rely on those ratings in a very real way, unlike the average hobbyist, consumer or even light-duty electrician.  If someone in a management position thinks, like you do, that UL or Intertek ratings are a reliable indicator of quality, they may end up buying that rubbish for an application where it counts.

A Fluke 28-II or 87V-MAX will be rated CAT III/1000V, CAT IV/600V and IP67.  They are made by Fluke in the US and cost around $500 or so--and have the limited lifetime warranty.  The Southwire 11060S is also CAT III/1000V, CAT IV/600V and IP67, all certified by UL.  They are made by Shenzhen Everbest (CEM) and cost around $100.  I do not know what branch of the UL did the certification, but I doubt they mailed their samples to Pennsylvania.  So likely the same story--certification done by local Chinese branch.  I have no idea if that matters.

https://www.electriciantalk.com/attachments/xlhhln0-png.138650/

"examination and testing....revealed that the meter's design and manufacture was not consistent with its Underwriters Laboratory (UL) listing."

https://www.govinfo.gov/content/pkg/USCOURTS-kyed-7_14-cv-00175/pdf/USCOURTS-kyed-7_14-cv-00175-0.pdf

So there you go.  And if you read the case, you can see that Southwire was able to walk away by disclaiming any knowledge of the particulars of the products that they sold with their name on them.  So if you just like having those ratings printed on the front and don't care how well they are backed up because you don't actually need them, go for the deal.  In my view, this should be a criminal matter, but there's just too many people making money to let a burned electrician get in the way of prosperity.



« Last Edit: September 27, 2021, 06:17:06 pm by bdunham7 »
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 
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Offline bdunham7

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Re: Handheld meter robustness testing
« Reply #4140 on: September 27, 2021, 05:25:56 pm »
Left on for 10 seconds, survives just fine at the nominal 245V here. Readings a smidge low as the PTC recovers.

So I'm curious about why these tests would be conducted at those levels on meters with a CAT-anything label at.  Should the meter not withstand, without damage, the application of full rated voltage (1000V in this case) to any input on any setting?  AFAIK, even supposedly fragile CAT I bench meters will pass that test.  Some older pre-CAT bench meters have separate, lower specifications for voltage protection on ohms and such, but even the old Fluke 8842A will pass that test.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline Fungus

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Re: Handheld meter robustness testing
« Reply #4141 on: September 27, 2021, 05:51:12 pm »
Left on for 10 seconds, survives just fine at the nominal 245V here. Readings a smidge low as the PTC recovers.

So I'm curious about why these tests would be conducted at those levels on meters with a CAT-anything label at.  Should the meter not withstand, without damage, the application of full rated voltage (1000V in this case) to any input on any setting? 

That's the theory but you never know for sure.

eg. A freebie DT830 will measure 1000V on the voltage range but I bet it wouldn't survive on one of the resistance ranges and I know it wouldn't survive on a current range.

Meters with "1000V" printed on the front and 250V fuses in them are quite common in the $25-meter world.
« Last Edit: September 27, 2021, 05:53:29 pm by Fungus »
 

Online rsjsouza

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Re: Handheld meter robustness testing
« Reply #4142 on: September 27, 2021, 06:06:16 pm »
...
Is it a third party independent testing a better scenario than self-certification or reputation alone? Yes, of course, especially since most people don't understand the technicalities of what they are buying
So our views coincide on the matter of independent certification.
Indeed. Why wouldn't someone want a reliable third party that verifies a manufacturer's claims in a very reproducible, reliable and uncompromised way? We don't have this today. That is the gist of the discussion.

- unfortunately this hasn't been he ideal scenario as time and time again it has been proven it is caveat emptor. That is why youtube and the internet have been acting as a "fourth party" source of information.
The problem with relying on information from YouTube or any other form of social media rather than information from independent testing and certification companies is quite obvious to me. If you have to take any information from independent testing and certification companies with a grain of salt, information on social media requires a truckload of skepticism and common sense - and time. Since I don't have much common sense and very little time, I always prefer to rely on information from independent testing and certification companies, however flawed it may prove to be in some cases.
I fully understand your stance, as there are things in life that I have to rely on an evaluation from a cert or government agency - food, utilities (gas, water) and pharmaceuticals being a few of them. Regardless, it only takes you to get burned once or twice by a product that was supposedly evaluated from these agencies to make you get smart about it. Examples galore, both in this thread with something of a niche product such as a multimeter and of more general public interest, such as the scandal where several cities in the state of Michigan had lead poisoned water for decades.

The SNR of the Internet and Youtube, although narrow, is of great use to provide an outlet to bring discussions to light that were unthinkable a few decades ago. Myself and many people I know rarely do a capital expense without looking at reviews, videos, opinions on the internet, as UL/Intertek/TÜV certified logos only do so much to let a ton of crap to the marketplace (and there is even the subject of falsifications).

The Southwire example pointed out by bdunham7 is a good example. Southwire and CEM probably have an indemnification clause where the ODM takes all responsibility for their crap, and any legal battles must be solved in the COO (China in this case). And THAT'S the kind of legal crap that cert and government agencies and OEMs find to skirt the law and reduce their seriousness and trust with the general public.
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Offline bdunham7

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Re: Handheld meter robustness testing
« Reply #4143 on: September 27, 2021, 06:08:09 pm »
That's the theory but you never know for sure.

 :o

I'm referring to meters that some claim to be properly rated, not ones where there isn't any dispute that the CAT info printed on them is a bad joke.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4144 on: September 27, 2021, 06:59:44 pm »
I understand that it is not exacly the same setup...

Again, they are not even close.  And again, the generator was designed not to simulate AC mains conditions, or anything even close to it. 

Online joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4145 on: September 27, 2021, 07:08:15 pm »
Left on for 10 seconds, survives just fine at the nominal 245V here. Readings a smidge low as the PTC recovers.

So I'm curious about why these tests would be conducted at those levels on meters with a CAT-anything label at.  Should the meter not withstand, without damage, the application of full rated voltage (1000V in this case) to any input on any setting?  AFAIK, even supposedly fragile CAT I bench meters will pass that test.  Some older pre-CAT bench meters have separate, lower specifications for voltage protection on ohms and such, but even the old Fluke 8842A will pass that test.

Link to the persons posts who had asked about this may be found here:
https://www.eevblog.com/forum/repair/uni-t-ut61e-diode-mode-repair/

Some of the smaller PTCs are only rated for 500V.  Some meters have only a single PTC which if the low voltage clamp is active, will have well over 900V across them....  Maybe....  Turn the dial, I suspect you will get a light show. 

***
Quote
I'm referring to meters that some claim to be properly rated, not ones where there isn't any dispute that the CAT info printed on them is a bad joke.

Sorry, I missed that part.   If a KVDC were applied with unlimited current and the function switch were rotated, I suspect you would burn the contacts on most meters.  I wouldn't recommend anyone attempt it.   

 
« Last Edit: September 27, 2021, 07:20:22 pm by joeqsmith »
 

Offline bdunham7

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Re: Handheld meter robustness testing
« Reply #4146 on: September 27, 2021, 07:14:37 pm »
Again, they are not even close.  And again, the generator was designed not to simulate AC mains conditions, or anything even close to it.

Do they need to be?  HiPot testing is a valid method of looking at potential HV breakdown (obviously not L-L in a normal operating mode) without riding on any mains, so why not consider it as transient HiPot method?  It certainly would at least be a usable diagnostic tool that can be used to non-destructively find weak points.  One would have to learn how to interpret the results just like you do with an old engine analyzer ignition scope.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Offline bdunham7

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Re: Handheld meter robustness testing
« Reply #4147 on: September 27, 2021, 07:23:10 pm »
Some of the smaller PTCs are only rated for 500V.  Some meters have only a single PTC which if the low voltage clamp is active, will have well over 900V across them....  Maybe....  Turn the dial, I suspect you will get a light show.

Well that doesn't sound very robust!  I don't know if that is a failure to meet a standard or not, but it seems like a basic expectation to me.  Every CAT labelled meter I currently have that isn't known junk should pass that test.  Some of them already have by accident.
A 3.5 digit 4.5 digit 5 digit 5.5 digit 6.5 digit 7.5 digit DMM is good enough for most people.
 

Online joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4148 on: September 27, 2021, 07:33:25 pm »
Again, they are not even close.  And again, the generator was designed not to simulate AC mains conditions, or anything even close to it.

Do they need to be?  HiPot testing is a valid method of looking at potential HV breakdown (obviously not L-L in a normal operating mode) without riding on any mains, so why not consider it as transient HiPot method?  It certainly would at least be a usable diagnostic tool that can be used to non-destructively find weak points.  One would have to learn how to interpret the results just like you do with an old engine analyzer ignition scope.
So you are suggest to use a high pot tester across the meter with it set to the volts mode? 

I've seen a few people post videos (including Dave) using an insulation tester. 

There was a guy posting about using a stun gun to test meters.  I wrote them but they never responded.   

Another option would be to actually get a combo generator tied to the mains and a nice blast shield.

All fun ideas and if anyone starts a channel where they run the meters this way, I will watch. 

Online joeqsmithTopic starter

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Re: Handheld meter robustness testing
« Reply #4149 on: September 27, 2021, 07:41:01 pm »
Some of the smaller PTCs are only rated for 500V.  Some meters have only a single PTC which if the low voltage clamp is active, will have well over 900V across them....  Maybe....  Turn the dial, I suspect you will get a light show.

Well that doesn't sound very robust!  I don't know if that is a failure to meet a standard or not, but it seems like a basic expectation to me.  Every CAT labelled meter I currently have that isn't known junk should pass that test.  Some of them already have by accident.

Maybe start reading here.  Dave chimes in.  So do I. 
https://www.eevblog.com/forum/testgear/eevblog-121gw-discussion-thread/msg1580530/#msg1580530


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