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THE "amp-clamp" and clamp-on ammeter problem thread

JST

Diamond
Joined
Jun 16, 2001
Location
St Louis
We have had a number of threads in which there have been claims that appear to blame "amp-clamps" or clamp-on ammeters, for confusion due to power factor issues.

So, here is the thread to argue about that. I am considering deleting such discussions from other threads, both current ones, and in future..

I invite those believing that "amp clamp ammeters" are the problem, to post here, and explain in detail why these useful tools are considered to be the problem which leads to confusion where "reactive currents" are concerned.

Here is a quote which started the last discussion:

"Gee, who would have thought it? Somebody hangs an amp-clamp on their device, and the first words out of their
mouth are: well *that* doesn't make sense.

Amp-clamps. Great for starting "is it real or is is imaginary" [1] threads on this forum.
"
 
I have a FLuke rms meter with current probe. To be honest, never used it after just checking that it worked.
If people check their designs with more vigor before power-on a lot of problems can be avoided.
 
Unfortunately, most of the people here are skilled at metal working and largely uneducated about electricity. The opportunity for instrument makers like Fluke is to incorporate a watt meter at a reasonable price. Fluke makes power analyzers but at $4000 and up the average shop is not likely to have one. Another issue is that to make power measurements, connections need to be make to the voltage source of the current, not always easy or convenient. Perhaps makers of 3 phase convertors could offer a wattmeter as an option on their control panels.

Tom
 
Amp clamps read the approximate current regardless of whether it is in phase or out, which of course you know. The inevitable variations in fit of the two pieces and the exact position of the wire it is clamped on means that they will not be a super accurate meter, but they are plenty good enough to tell if your motor is running right.

If someone puts one on a circuit with a low power factor and gets a high reading, the problem is in the operator's head, not the meter.

I don't see why there should be any controversy.

Bill
 
Cannot disagree.

Was hoping ol' Jim R would post a detailed explanation of just how an amp-clamp is worse than anything else, and more misleading.

Of course, then there is the question of just exactly what other type ammeter would be superior and have less resulting confusion..... there are not many choices, and they should all read the same for the type they are (average or rms).
 
Most midrange ones achieve accuracies of 2.5% or better in many cases. The only times when I've had serious issues is very near to (within the same cabinet as) high current buses while measuring sub-amp values.

Power clampmeters are not in the $4k range; AEMC (this one also does datalogging and power quality and harmonics; I have its big brother) and Extech among others make decent gear for around a tenth of that.
 
We bought a set of 3 "off shore" units that have a digital display in a panel control housing with a remote coil.

We use them for solenoid currents in SCADA system but they seem to measure to small sub amp levels and 19 bucks for the 3.

Also have fluke and others a long with a panel mount device made for 3 phase that reports volts and amps.

All report similar things, amps.

The 19 buck set is The most useful as it can show 3 unique measurements at same time so one can see the balance of power in a load.

Power factor and phase angles are usually not what most folks are looking at.

Sent from my SAMSUNG-SM-G930A using Tapatalk
 
Cannot disagree.

Was hoping ol' Jim R would post a detailed explanation of just how an amp-clamp is worse than anything else, and more misleading.

Of course, then there is the question of just exactly what other type ammeter would be superior and have less resulting confusion..... there are not many choices, and they should all read the same for the type they are (average or rms).

Meahhh...

I like the Weston 155 or Crompton Hi-Q derivatives meself...

Not that I'm especially "old fashioned".

Just that there are no dam'-fool batteries to go flat!

Besides... a crackerjack machinist can actually MAKE either one.

Kinda stuff some among us usta to do in "School Science Fair" competition. Back when schools were still places to learn stuff. On-purpose, rather than by accident, even!

Try that with "integrated circuits" and "digital displays"...
 
Suggest you delete this thread. Not needed. This won't come up again. Until the next time it does....


I am still hoping for that explanation of the perils of the clamp-on ammeter. Because there will not be any more discussion of the matter in the various threads that may in fact come up.
 
Cannot disagree.

Was hoping ol' Jim R would post a detailed explanation of just how an amp-clamp is worse than anything else, and more misleading.

Of course, then there is the question of just exactly what other type ammeter would be superior and have less resulting confusion..... there are not many choices, and they should all read the same for the type they are (average or rms).

Fluke has the notorious "True RMS" meter.
 
What do you mean by "notorious"?

Tom

The definition of that word can be taken two ways ...

-generally known and talked of

-widely and unfavorably known

If I were to own the meter then I would pick numero uno ...
Don't get excited, I have one. But have never forgotten about my Simpson.
 
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Most of the time that I have used a clamp on ammeter has been when a breaker has tripped and I want to know if the breaker has died or if something in the load, if it says it should pull 5 amps and it is reading 20 I start looking at wires, junction boxes etc and will normally find some bare wire or the such. The accuracy of the clamp on meter never even crossed my mind, I simply don't want to spend half a day taking a machine apart and putting it back when all I really needed was a $15. circuit breaker.

It could be a sign of the times that folks got tired of arguing with our spouses and decided here would be better, cuts down on the cold sholder and hallway sex( You know, where she says F--- You! as you pass in the hall).

Seems these days folks on PM are arguing about all kinds of things that don't mean much, I guess other forums as well as I have had letters from several asking members to ease up and be polite to each other.

One morning a while back Wonder Woman woke up in quite a mood, she chewed my ass for an hour straight while having her first cup of coffee about 15 subjects if it was one, about then I picked up a salt shaker and banged it down in front of her, she asked what the hell that was for, I told her when she got done bitching I wanted to argue about that. It was quiet for a bit followed by the beginnings of a normal day. Sometimes I recon we just get to feeling that way and need to argue about something, might as well be a clamp on ammeter.
 
The bad news is that for ac circuits you can't just measure amperes and volts to calculate power. You need an actual watt meter or power meter and the best ones also determine things like power factor, crest factor, etc.

Had more than one facilities manager over the years say "why do you guys have to make everything so complicated" when we tried to explain how little useful information his clamp-on ammeter actually provided.
 
I told me that. In fact I told you that too.

Well.. "news flash". I'm hard-of-hearing. Or don't listen well. Not uncommon on PM?

:)

Whichever.

"The-people" "run what we got" for test equipment and bench instruments, same as we do for machinery.

As-had. "Under our roof", in our hands and our budgets. Imperfections and all.

Not as we WISH it was, cost no object.
 
Well.. "news flash". I'm hard-of-hearing. Or don't listen well. Not uncommon on PM?

:)

Whichever.

"The-people" "run what we got" for test equipment and bench instruments, same as we do for machinery.

As-had. "Under our roof", in our hands and our budgets. Imperfections and all.

Not as we WISH it was, cost no object.

You could put a warehouse full of test equiptment of every kind in front of most of us but we would not know what to do with most of it, a few would be willing to read up on how to use some of the unfamilliar. Having it available is not the same as knowing what to do with the tool or the information it will generate. I have been around machine shops most of my life (started when I was 8 in pops motorcycle shop) I have fumbled my way through most mechanical repairs OK but looking for help with most electronic ones. 20 years ago I had a big disagreement with my HFO, Haas put me through their 2 week crash course for the repair of their machines, sent me home with a 4 foot tall stack of books. I learned enough to poke around a bit with a multimeter and clamp on ammeter then make a call to the factory for guidance. More test tools wouldn't help that me much.
 
You could put a warehouse full of test equiptment of every kind in front of most of us but we would not know what to do with most of it, a few would be willing to read up on how to use some of the unfamilliar. Having it available is not the same as knowing what to do with the tool or the information it will generate. I have been around machine shops most of my life (started when I was 8 in pops motorcycle shop) I have fumbled my way through most mechanical repairs OK but looking for help with most electronic ones. 20 years ago I had a big disagreement with my HFO, Haas put me through their 2 week crash course for the repair of their machines, sent me home with a 4 foot tall stack of books. I learned enough to poke around a bit with a multimeter and clamp on ammeter then make a call to the factory for guidance. More test tools wouldn't help that me much.

Depends on how it is approached. For over 40 years, I had "issues" with professionally trained HR munchkins.

I refused to adopt the "Strengths and Weaknesses" model of performance review, opting instead of the loaded "guilt trip" term of a "weakness" to the more pragmatic one of "areas to seek assistance".

A(ny) person who can acknowledge such specialities where they - and the TEAM (or family) - are better SERVED by enlisting the aid of some OTHER team, family, or third-party do-er WILL ALWAYS do better, sooner, and be HEALTHIER if they "JFDI" and carry-on, feeling GOOD about it, NOT apologetic... so they can deliver what they ARE "good at".

"Cobbler, stick to thy last." Just because one CAN do a thing doesn't make that the best way forward,

Should be obvious? Nature doesn't confuse Eagles, Dolphins, Elk, and Bears with potatoes, Oak trees, oysters, or mushrooms.

But some folks just HAVE to try to force others to learn what they are more efficient and effective NOT diverting to bother with.

Thereby reducing, not enhancing, their overall capability and contribution.

Not many of us - even if "renaissance man" or "competent man" has been a lifelong goal - actually have to be fully self-sufficient, "Robinson Crusoe" style, after all.

Or at least not OFTEN?

I mean, even with a toilet-paper shortage, why would a person try to learn how to lick their own ass when so many dogs are out of a decent job?

:)

Don't fret. Don't "apologize".

Just "Run what you GOT!"

But "run" it well !
 








 
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