Poll

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

0-2000
7 (17.9%)
2k-4k
5 (12.8%)
4k-8k
14 (35.9%)
8k-16k
7 (17.9%)
>16k (most rubust meter ever made)
6 (15.4%)

Total Members Voted: 36

Author Topic: Handheld meter robustness testing  (Read 1149374 times)

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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1200 on: March 19, 2017, 07:57:56 pm »
If all of the shunts were identical, there are still some errors in the setup.  Sensing the voltage near the supply for example adds some error, it will not vary like the temperature sensor placement or the biggest problem, inserting the shunts into the clamps. 

To give you some idea of the variance of the jig, here is the plots showing the resistance across the entire 100 Ampere sweep for all of the 5mohm shunts.

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1201 on: March 19, 2017, 08:12:53 pm »
Two of these shunts were from CEM branded meters.  They appear to have the same diameter and length so we expect these two will behave the same.   Only looking at these two, the first graph shows their resistance.  The next plot shows their voltage drop.  These two were very linear across the entire 100A sweep.   The temperatures were within 70deg C which is better than I would expect as there is a large temperature gradient across the surface.  Those clamps are a plated brass with lots of thermal mass. 

One thing I wish I had explained was Watt density.  We are looking at the power dissipated with how much surface area the part has.  The Kunsuntest ZT102 and free HF meter both calculated out to 12W/in^2.  The nichrome with even higher resistance really pushes this up and why it makes good toasters and hair dryers. Lots of heat in a very small space.. 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1202 on: March 19, 2017, 08:16:15 pm »
For the few people that are interested, I have attached the raw data I collected during these tests.   Voltage, current, power and temperature.  One file for each shunt tested. 
 
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Offline Vgkid

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Re: Handheld meter electrical robustness testing.
« Reply #1203 on: March 19, 2017, 08:19:52 pm »
I look forward to watching the video. Unfortunately at the earliest it will be Monday, or Tuesday night.
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Offline tautech

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Re: Handheld meter electrical robustness testing.
« Reply #1204 on: March 19, 2017, 08:30:30 pm »
In no way have I seen the insides of as many DMM's as Joe but in cheaper ones the shunts seem to be made of copper or brass.  :--
Unless they're made of materials accepted for shunts like Constantan, no wonder there's some variability.  ::)
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1205 on: March 19, 2017, 08:49:36 pm »
In no way have I seen the insides of as many DMM's as Joe but in cheaper ones the shunts seem to be made of copper or brass.  :--
Unless they're made of materials accepted for shunts like Constantan, no wonder there's some variability.  ::)

Manganin is made up of about 86% copper, 12% manganese and nickel, so yes they do look like copper.   Constantan has about 55% copper and nickel.   

https://books.google.com/books?id=sxkPJzmkhnUC&pg=PA158&lpg=PA158&dq=constantan+or+manganin&source=bl&ots=AJxv8bmzp-&sig=0FcOzbS9QGymOEuqr71AYjH5p8M&hl=en&sa=X&ved=0ahUKEwi_0uqOuOPSAhWm7YMKHcPjCREQ6AEIajAL

Offline Vgkid

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Re: Handheld meter electrical robustness testing.
« Reply #1206 on: March 20, 2017, 06:36:21 am »
Nice job, I enjoyed it.
What was the software you were using?
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1207 on: March 20, 2017, 10:34:15 am »
Nice job, I enjoyed it.
What was the software you were using?
I use LabVIEW.

Voltage drop measures at 10.00 Amperes

Using large body HRC fuses
Brymen, BM869s, 312mV
UNI-T, UT61E, 239mV, Modified 
CEM, DT9939, 350mV
UNI-T, UT181A, 294mV
Fluke, 115, 280mV
AMPROBE, AM530, 353mV
Fluke, 107, 325mV
Other...
Cen-Tech, 98025, 131mV, No fuse
External Shunt, 10mV

I made one more attempt to further improve the UT61E by adding even more copper and reduced it another 20mV was all. 
« Last Edit: March 20, 2017, 11:16:14 am by joeqsmith »
 

Offline rsjsouza

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Re: Handheld meter electrical robustness testing.
« Reply #1208 on: March 20, 2017, 06:39:55 pm »
Joe, one more excellent video. Thank you for the work.

I think that Centech will start stamping their meters with "exclusive 100A fuse" in the 10A input. That or the input will actually be marked as 100A (20 sec max).  ;D
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Offline bitseeker

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Re: Handheld meter electrical robustness testing.
« Reply #1209 on: March 20, 2017, 09:48:24 pm »
LOL, yeah. Instant upgrade of fuse and higher current rating. Weee!
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1210 on: March 20, 2017, 11:33:28 pm »
Voltage drop of the meter test leads swept from 2 to 20 Amperes in 2A increments.   One meter stands alone....     

Offline Vgkid

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Re: Handheld meter electrical robustness testing.
« Reply #1211 on: March 21, 2017, 12:13:48 am »
Is that Centech yellow/green?
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1212 on: March 21, 2017, 02:46:42 am »
Is that Centech yellow/green?

You bet it is.  They could make the meter with 100A for a 20 seconds and if the shunt doesn't melt off the board, the leads would open.   

I wonder how the probes included with the two Kasuntest meters would do.  Better yet, I wonder what leads the 121GW will include.   

Offline Vgkid

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Re: Handheld meter electrical robustness testing.
« Reply #1213 on: March 21, 2017, 03:37:38 am »
You bet it is.  They could make the meter with 100A for a 20 seconds and if the shunt doesn't melt off the board, the leads would open.   

I wonder how the probes included with the two Kasuntest meters would do.  Better yet, I wonder what leads the 121GW will include.   
You should have filmed that.
on the 1.21GW That will be a good guess.
I have a pair of Probemasters on my 87-1, and a set of modified(cut off safety shroud) gold Brymen's on the 3456A, with a set of Fluke probes floating around. My biggest problem with the HF meter, is that the probes are too short :( .
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1214 on: March 22, 2017, 12:12:37 am »
He mentioned they would start testing in January but I guess that was pushed out.  Better to make sure they are happy with it before it gets released. 

I did capture the lead tests.  Here is the free cen-tech meter leads.   
https://youtu.be/fQowDZstguw?t=1222

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1215 on: March 24, 2017, 01:55:50 am »
The UT61E, a real 20A meter.   

Some calculations,  fuse & Manganin sheet stock
https://www.digikey.com/product-detail/en/schurter-inc/0090.0020/486-2707-ND/2644881



Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1216 on: March 24, 2017, 01:57:27 am »
Current through the shunt, voltage across the shunt and calculated resistance compared with the original shunt.

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1217 on: March 24, 2017, 01:59:19 am »
Much lower Watt density.    Note also the added copper in the terminals. 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1218 on: March 24, 2017, 02:00:59 am »
Checking alignment against the Brymen BM869s.

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1219 on: March 24, 2017, 02:09:22 am »
A nice and toasty meter.  Brymen looking at the drop across the modified UT61E.  The UT61E will over range a bit over 22 Amperes. 

Does it reach 200mV at 20A like their claim in the Kasuntest manual, no.  The fuse and shunt get pretty warm with 10W but I ran it like this for a five minutes with no problems.   

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1220 on: March 24, 2017, 11:43:04 am »
The Kasuntest KT6000 at 22A.  2 more Watts.

Offline Vgkid

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Re: Handheld meter electrical robustness testing.
« Reply #1221 on: March 24, 2017, 04:07:00 pm »
Where did you get the manganin sheet from?
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Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1222 on: March 24, 2017, 04:21:54 pm »
Watched Dave's reviews of the Gossen power meter.  :--  No way I would spend over $1000 on a meter with a tacked on resistor.  Too bad, like some of the features.  Review was not too great.  Hardly turned the thing on.   

Looked at various pictures of the internals of other Gossen products.  Some look like they were made in the 90's. 

Now looking at the lower end Extra.  From the manual, they mention the KS30 for additional protection.  Search their site, nothing.   I would like to get the KS30 with it if I go this route but can't find anyone who carries it.   Time to send them an email.   

Quote
The multimeters are protected against transient overvoltages of
up to 8 kV with wave-front durations of 1.2 ms and halftimes of
50 ?s in the voltage measuring range. If longer pulse durations are
expected, for example when conducting measurements at transformers
or motors, we recommend the use of our KS30 measuring
adapter. It provides protection against transient
overvoltages of up to 6 kV with wave-front durations of 10, and
halftimes of 1000 ?s.
Continuous load capacity is 1200 VRMS. Additional influence error
caused by the KS30 measuring adapter amounts to approximately
-2%.



Their response below. 

Quote
Daer Joe,

Thank you for your Email.

I just checked the article KS30 and it was discontinued several years ago.

This was a mistake in our manual and we will correct it asap.

If you require a quotation for M250A you can contact our US subsidiary:

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1223 on: March 24, 2017, 04:24:52 pm »
Where did you get the manganin sheet from?

Came from a friend of mine.  Looks like you can order wire or sheet stock of pretty much any size.   I plan to make a video of the 61E but am still waiting on the proper fuses.  This is were a lot of the heat is going now.  Old 15A Fluke fuse, surprised it survived over 20A. 

Offline joeqsmithTopic starter

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Re: Handheld meter electrical robustness testing.
« Reply #1224 on: March 26, 2017, 03:29:06 pm »
Measuring 20A with the UT61E.  This meter is starting to look as bad as my UT90A.   



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