Author Topic: UT210E Problem measuring AMPS!!! :(  (Read 7037 times)

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Offline 2N3055

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #25 on: May 12, 2020, 07:53:21 pm »
This is a clamp meter with a 2.5% +/-5 digits spec, so you will only achieve +/- 0.1A accuracy at low amperage (like below 4A).  So temper your expectation on what this meter can really deliver in terms of accuracy.  Due to its design, it is hard to achieve the 0.1A accuracy in clamp meters throughout its measurement range even for expensive meters, let alone a $10 Uni-T.
It has 2A range.. 2.5% +/-5  is +/-5mA+/-5d max error..

I'm going to say It has 2A range.. 2.5% +/-5  is  +/-50mA +/-5d or +/-55mA.    Maybe we can vote on it and see who's right.  :-DD
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Offline AVGresponding

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #26 on: May 12, 2020, 07:56:55 pm »
Don't be too quick to write off cheap clamp meters, unless you've checked the thing first.

I have a cheap Mastech 2108A, icr what it cost, but was certainly less than 30USD.

The low dc range is 40A, with 10mA resolution.

Obviously I was curious about the accuracy, so I gave it some on the job testing.
I was helping out a fellow sparky who was commissioning a small fire alarm panel; he'd found the current draw was so small that putting his DMM in series on mA setting (Fluke 77 iirc) the panel just wouldn't power up.
The reason you need to do this is for fire regs, you have to measure the quiescent current and the full alarm current as part of the battery capacity formula.
So I used the Mastech, and we were looking at around 30mA quiescent, and 50mA with all the sounders running.
Since that's effectively in the noise as far as this meter goes, I was rather sceptical, and went for a rummage around in my van, and dug out a precision shunt I'd made.
Using this we measured the currents again... and found them the same, though with the shunt we got an order of magnitude better precision.
Nevertheless I was pretty surprised, and even impressed, with the performance of the cheap clamp meter.
nuqDaq yuch Dapol?
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Offline NoisyBoy

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #27 on: May 12, 2020, 08:14:48 pm »
Good point, I have seen similar scenarios before.

However, I have also observed cheap meters often are nonlinear in reading.  The error may be low at some point, but huge at others, and likely you can even find a point where it is dead-on if you run it through a calibrator, but I would be careful to rate any overall accuracy from limited data points. 

Meters with good linear results are those with multiple cal points across each function and on each range selected, unfortunately, most low cost meters do not offer it. 

So, while at some amperage range, the Uni-T may offer <.1A accuracy.  My point is it is very unlikely that it will deliver this accuracy across a wide current range.
 

Offline AVGresponding

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #28 on: May 12, 2020, 08:19:08 pm »
That's a fair point, and tbh I've not checked it at the other end of the range.

The aforementioned shunt will measure up to 70A or so before it becomes too hot to handle, so now I just need to fathom a 39A or so load to check them against each other...
nuqDaq yuch Dapol?
Addiction count: Agilent-AVO-BlackStar-Brymen-Chauvin Arnoux-Fluke-GenRad-Hameg-HP-Keithley-IsoTech-Mastech-Megger-Metrix-Micronta-Racal-RFL-Siglent-Solartron-Tektronix-Thurlby-Time Electronics-TTi-UniT
 

Offline cdev

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #29 on: May 13, 2020, 02:48:20 am »
My UT2010E meets the specs - it can measure a low current to 1 ma accuracy, which for the price was a great deal. Also the non contact meter is very useful. And it has a decent voltmeter, ohmmeter, so I think it was a great purchase. I wish it could connect to a USB port, but you cant have everything. I paid around $30.00 for it. Totally happy with it.
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Offline cdev

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #30 on: May 13, 2020, 02:59:18 am »
Looking good!  Your degausser is designed for this use. Mine are for my old cassette deck and for erasing old VHS tapes.

Yes, that is exactly what I meant.  its basically the same thing. Maybe its unnecessary but I always turn it on and only then bring the item to be degaussed into the field, leave it there a bit, maybe move it around a bit to make sure its gotten a good degaussing and then remove it from the magnetic field, while its still energized. I am trying to not remagnetize it by breaking the circuit in the middle of a cycle while the object to be degaussed is still in the field.

If I were you I would just make a coil with a bunch of nails and a long piece of thin wire. You can energize it with a transformer, dont use mains voltage. You dont need a super lot of power and indeed, less is more in this situation. You'll likely not need a degausser that often.

You dont want to damage the UT210e

Obviously no want wants to damaged any of their equipment.  I suspect you meant damage it from something to do with magnetizing the head or degaussing it.   Care to explain?

As far as what's required, I was using about 600 gauss peak with a half second decay. 



That is definitely the way to go.
« Last Edit: May 13, 2020, 03:03:14 am by cdev »
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Offline joeqsmith

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #31 on: May 13, 2020, 03:09:58 am »
That is pretty much what I do.  Turn it on near the thing I am trying to clear, and never turn it off until I am far away.  Depending on what it is, I will rotate the eraser in the field.  The homemade one was designed for this probe.  You can find my build here:

https://www.eevblog.com/forum/testgear/a-look-at-the-uni-t-ut210e/msg1040540/#msg1040540

Offline cdev

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #32 on: May 13, 2020, 03:25:08 am »
Joes's coil where you put the clamp into the magnetic field is clearly the way to go. It puts the meter right into the magnetic field. make sure you use enameled (insulated) wire and not bare copper wire which would defeat the whole purpose and likely start a fire! (joke)

You can use any electromagnet, any kind at all, as long as you run it on AC, and not DC. 50 Hz, 60Hz, whatever. I being an old school kind of guy who used to dote on my audio hobby, have a tape head degausser and also a large tape eraser. Either one would do. The most important thing is safety. mains voltage of 115 v is high enough to hurt or perhaps kill somebody, 220 volts or more is at least twice as dangerous. So make sure whatever coil you use has enough length to not present a short, any demagnetizer will get warm, thats okay, but especially make sure its well insulated. When I said big coil I meant big enough to not blow fuses or melt at a bare minimum, but it shouldnt get too hot either. Dont use wire thats so thick it cant be long enough. Measure its DC resistance to make sure its high enough to not be a heater instead of an electromagnet. A good degausser will hum when you energize it a bit.


Hi cdev ... sounds smart solution... but can you give more details? Nails? what transformer to use i have for eg a 220v 12v  from battery charger.... what cable and how many turns would you use...after that is clear.. would you pass them close trough the clamp or meant wrap the jaws or do turns like if you were measuring current.. im talking about DC measurementes.
Yes the device my UT210E works perfect in all other functions that is why im so interested in its rescue.
Yes im not gonna opem to touch trimpots nor update firmware wich would be great though.
Joe yo know too much and showed your knowledge.. but from point of view of myself as an user i wanted just my device working at least on +- 100mah error and would be more than happy i bet with your device could be achieved.
"What the large print giveth, the small print taketh away."
 

Offline marce002Topic starter

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #33 on: May 13, 2020, 09:48:31 pm »
ok thanks again, i think i will end up doing it with a microwave transformer with an "E" reformed core, because will be the most easy to get materials here around..... the truth is that I do know
very well what to do once it is energized to 220v in the primary and an "open sky sight" to let the magnetic field scape from the core upwards.... a mean,,, should i manually get the clamp to the middle part of the core and then fast very fast rise it until the efects are far and turn it off? that in 20A scale where the offset is 5A, not in the 2A scale where i can only see 0L (out of scale)
 

Offline cdev

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #34 on: May 14, 2020, 08:37:18 pm »
I'd use something like Joe's degaussing coil with it's added switch. Its good to mess with mains voltage as little as possible. That why I got my UT-210E to tell you the truth.
"What the large print giveth, the small print taketh away."
 

Offline gyrex

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #35 on: September 01, 2024, 10:32:22 pm »
I've got a similar issue with my UT210E where my DC Amps is reading 0L. Regarding degaussing, would a degausser like this work? https://www.aliexpress.com/item/1005007458615469.html

Do I need to be able to pass the entire meter through the hole or like the degaussing video, can I just put the clamp opening in the hole? Apologies if these are stupid questions but I'm not sure how to fix my meter.
 

Online ledtester

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #36 on: September 01, 2024, 11:32:50 pm »
I've got a similar issue with my UT210E where my DC Amps is reading 0L. Regarding degaussing, would a degausser like this work? https://www.aliexpress.com/item/1005007458615469.html

Here's a good video on those Aliexpress degaussers - including teardown, theory of operation and a way to improve it.

Adding a PTC to a Chinese Demagnetiser making it easier and safer to use - TheHWCave
https://youtu.be/AhTYBPdJG7A
 
The following users thanked this post: Kean, gyrex

Offline Kean

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Re: UT210E Problem measuring AMPS!!! :(
« Reply #37 on: September 02, 2024, 03:55:29 am »
Here's a good video on those Aliexpress degaussers - including teardown, theory of operation and a way to improve it.

Adding a PTC to a Chinese Demagnetiser making it easier and safer to use - TheHWCave
https://youtu.be/AhTYBPdJG7A

Thanks for this reminder.  I have one of these watch degaussers that I've used on my UT210E's (with some success) and I've been meaning to do a similar mod.
 


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