Handheld meter robustness testing

[Maxlor]

Finished with the current source test setup.   I ran some tests with it using a few different probes and the differences are pretty dramatic.   I already melted one lead (in the range it was rated for!).

Tease!

Looking forward to the video

[joeqsmith]

   I am just trying to get a feel for how it is all going to work.    Say you have two meters.  Both have a 10A current input.  You would sort of expect the leads that were supplied with the meter to handle 10A forever.    You would expect the leads would not drop too much voltage and dissipate a lot of heat.     But some brands seem like they have leads that would not even handle 5 Amps for an extended period.     One I put 50 through!   Yea, that's 50 Amps and it did not open up!   One was very cheap, the other a name brand.     

The software I wrote will record the data that is collected for each lead and allow me to view all of the probes performance at once.  It would also allow me to use the data to compare other leads later on..

When 5KY provided me with the meters, he did not supply the leads but it does appear that there many of them are purchased through the same supplier.    The other problem I see is some of the leads are not marked and I am not sure what meter they came with.   Depending how this works out, I may add lead testing to any reviews I do down the road.

[saturation]

Wow.  If those leads are NRTL certified that would be a big problem.

Finished with the current source test setup.   I ran some tests with it using a few different probes and the differences are pretty dramatic.  I already melted one lead (in the range it was rated for!). 

[joeqsmith]

I have no idea if any of these probes are certified.  They have a CE mark on them and most will state CAT ...   

Looks like a nice day outside.  I have my wireless router and my tablet PC ready....   The indoor testing is first.  Here is the line up.  All virgin except I plan to use one of my own set of probes that I normally use as a sort of base line.   

[tautech]

Fry up at Joes place everybody, bring your own plate, knife, fork and ....

[saturation]

Any results would certainly be helpful!  FWIW all Fluke and Amprobe branded probes are NRTL.

I have no idea if any of these probes are certified.  They have a CE mark on them and most will state CAT ...   

Looks like a nice day outside.  I have my wireless router and my tablet PC ready....   The indoor testing is first.  Here is the line up.  All virgin except I plan to use one of my own set of probes that I normally use as a sort of base line.   

[Fungus]

  I am just trying to get a feel for how it is all going to work.    Say you have two meters.  Both have a 10A current input.  You would sort of expect the leads that were supplied with the meter to handle 10A forever. 

A lot of those meters say things like "10A for 10 seconds maximum" in the fine print.

[joeqsmith]

In the video I will provide the CAT rating, current rating and the wire insulation OD?   I may measure the length as well.   

I am leaving the probes all bundled up for the HV test basically trying to get a worst case condition.   

Any results would certainly be helpful!  FWIW all Fluke and Amprobe branded probes are NRTL.

For the high current test, I will not be using a meter.  I would have jumped out the fuses for this test anyway.  No plans to pussy foot around.  I will run one lead at a time.   I am planning to start at 2A then increase every 30 seconds by 2A.   So say 40A or 20 steps, so 10 minutes per probe.  I plan to measure the voltage drop across the test leads and the current to get the power dissipated.   The whole setup is controlled by a computer so I will just sit back and monitor the action.   

The 40A I am not so sure about.  The current source is no problem.   Using some 6AWG with my custom made connectors and the power supply is a couple of KW.   I guess we just see how it goes.   If the leads handle 40, I may increase it to 80 or 100.     The sun is out and we have a bit of wind.   It's a perfect day for it. 

A lot of those meters say things like "10A for 10 seconds maximum" in the fine print.

[joeqsmith]

I kept 5KY's UT61E for a mechanical sample because it is such a popular meter.  I could jumper out the fuse on this meter and run it.  I can see someone doing something like this in real life.   

Well the coffee is gone, time to get back to work.

[Fungus]

I kept 5KY's UT61E for a mechanical sample because it is such a popular meter.  I could jumper out the fuse on this meter and run it.  I can see someone doing something like this in real life.   

So can I 

Last time I did "multimeter workshop" at the Arduino club nobody had a multimeter with an intact fuse on the 200mA range. Not even one.   

[joeqsmith]

What would a person use?  Maybe a bolt?  Too hard to find something that fits.   Wire!!!   So RG58 braid packed in there. 

I'm sure the UNI-T clan is going to be all up in arms.  I can hear it all now.  "Only and idiot would do something like this!!"      Maybe the professional trolls will even chime in on the Youtube comments....

Time to head outside...

[Fungus]

What would a person use?  Maybe a bolt?  Too hard to find something that fits.   Wire!!!   So RG58 braid packed in there. 

The traditional fuse replacement (in the USA) is a .22 bullet.

[joeqsmith]

I checked, it was too short and I don't own a 22 mag. 

Testing is going pretty good.  I am running them all to 20A to start.  Amazed what a difference I am seeing.   I get the bad feeling that like when the 87V did so poorly, the high end leads may not be the best....   Lots more to go. 

[joeqsmith]

What are your tests leads insulation made of?  Vinyl?    Silicone?  Other?   

[Muttley Snickers]

Like many others here I have numerous meters with various leads sets, funnily enough I very rarely if ever use the original leads that come with the meters regardless of the quality, I've never been much of soft silicone fan because I find that out in the field they tend to get caught up on anything and everything, my preference is for a less flexible lead with a smooth rather than sticky insulating material, each to their own.

Years ago I bought 20 sets of cheaper average quantity leads just because they had all of the attributes I was looking for and they get given a hard time in factories, plants and machine shops with chompers all over the place. They are similar to the UNI-T UTL-23 leads and the specs say ABS, we bought a number of their meters years ago and most went back but I didn't mind the leads at the time so went hunting and loaded up for peanuts, otherwise the TL-71 leads that come with our 117's are very nice but I save the good leads for special occasions.   

[joeqsmith]

I was thinking asbestos after today.

All of the testing is done and I have started editing the video.  I need to work out some sort of conclusion.  Hope to have it uploaded by Monday.  In the mean time, here is a little spoiler.  If horizontal is samples, I bet you can guess the vertical axis.   The two data sets are from the same brand of probe.  One is fairly old, the other is the latest and greatest.....   

[SeanB]

What would a person use?  Maybe a bolt?  Too hard to find something that fits.   Wire!!!   So RG58 braid packed in there. 

I'm sure the UNI-T clan is going to be all up in arms.  I can hear it all now.  "Only and idiot would do something like this!!"      Maybe the professional trolls will even chime in on the Youtube comments....

Time to head outside...

Standard fuse replacement when I was younger was to wrap the fuse with some wire, typically some 2.5mm wire, or the foil out of a cigarette pack you grabbed off the nearest smoker.

For the larger fuses a 7.65mm R5 round was perfect as a replacement, there were always empty cases around.

[joeqsmith]

Some major abuse of some perfectly good, brand new test leads.   

[tautech]

Not the fry up that I would have expected with any of the cheap leads and that most withstood up to 20A or more is staggering.

Joe, did you do any probe lead length comparison that could have affected Vdrop results ?

[joeqsmith]

I had ran a few tests ahead of running the probes.  I calibrated the voltage using the Fluke reference.  The shunt used was decent.  Then I showed the setup with the UT210E.  I am also fairly confident that the majority of the loss was in the test leads cables and not the 6 AWG cables or my connections.  Of course there will be errors but my goal was really to try and test them the same and compare results..

So like you, not only was I also very surprised just how far I could push some of the test leads, I am also confident in the numbers I was throwing up.   

Seeing that very old Fluke lead holding 60A for that length of time was very impressive!   70Amps to finally fuse it!   And this is why you want a fused meter and don't want to put the wrong fuse or worse, defeat your fuse even if they do cost a few dollars each!   Better than burned hands!
 
As always, there were some mistakes during the video but the obvious one was I show the gray Mastech probes were the best, not the plain black and red.   Too much sun. 

Without knowing anything about the wire they used, its pretty hard to say anything about the resistivity.   Below, the brand, overall length, wire insulation OD, Resistance at 4A, Gold Plate

CENTECH, 32", 0.02", 0.375
Agilent, 55", 0.05", 0.047
Fluke (101), 55", 0.05", 0.047
HIOKI, 43", 0.04", 0.043,  gold
AMPROBE, 42", 0.04", 0.041
Brymen, 46", 0.045, 0.033, gold
KLEIN, 41", 0.045", 0.150
Mastech (plain), 40", 0.04", 0.074
VICI, 42", 0.042", 0.084
Mastech (gray), 41", 0.04", 0.026
ProbeMaster, 46", 0.04", 0.031, gold

Not the fry up that I would have expected with any of the cheap leads and that most withstood up to 20A or more is staggering.

Joe, did you do any probe lead length comparison that could have affected Vdrop results ?

[tautech]

Thanks Joe, great work as always. 

That there's a range of 13" over the lead lengths is surprising  so is there any sense in recalculating the results to reflect the lower R/foot leads. 

[joeqsmith]

I would need to know the resistivity of the wire. 


Ignoring the KLEIN and Centech test leads, the following graph shows the remaining probes voltage drops at 4 Amps.   Note that the sample time is roughly 10Hz, or about 10 seconds of data.   For the most part, the readings are fairly stable.

Thanks Joe, great work as always. 

That there's a range of 13" over the lead lengths is surprising  so is there any sense in recalculating the results to reflect the lower R/foot leads. 

[joeqsmith]

Oh wait, are you thinking just normalize the data?  Sure, this makes sense.   

Attached is the drop with 10 Amps through them. 

[joeqsmith]

Here is the data for all of the probes except the Centech at 20 Amps.   That red line at the top is the VICI lead which is marked 20A, where all of the others are marked 10A.       I would expect that VICI lead to be the lowest of the group!   

And this is why we run the tests.

[joeqsmith]

Ohms/inch on right.  Treating the probe as homogeneous, ignoring the probe tip, banana jack, plating, crimps.   

I will normally use a set of the gold Probe Master probes like I tested for general use.  For finer areas, I use the Fluke needles that were on the far right of the bench.  For big stuff, I have the modular type Probe Masters with most of the ends.  A fair investment but comes in handy.   It is also rare I will use a hand held meter to measure current directly.