Author Topic: Do multimeters measure ACA  (Read 345 times)

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Online brownt

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Do multimeters measure ACA
« on: July 12, 2018, 01:48:19 pm »
Hi,

does the average digital multimeter measure AC amps?

thanks
 

Online blueskull

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Re: Do multimeters measure ACA
« Reply #1 on: July 12, 2018, 01:49:07 pm »
Define average. Most meters that can measure DCA can also measure ACA, but some can't measure current at all.
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Offline Conrad Hoffman

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Re: Do multimeters measure ACA
« Reply #2 on: July 12, 2018, 01:55:31 pm »
I'll say yes, but you have to wire them in-circuit. That makes them completely impractical for mains type work, where a clamp-on would be far better.
 

Online brownt

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Re: Do multimeters measure ACA
« Reply #3 on: July 12, 2018, 02:05:19 pm »
I see. what about analog meters, are they typically capable of measuring AC amps?
 

Offline JS

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Re: Do multimeters measure ACA
« Reply #4 on: July 12, 2018, 04:14:35 pm »
All analog meters measure ac amps, as the thing that moves the needle is current driven. If they have a sport of proves to choose from or always have a series resistor that doesn't let you do any practical measurement for current I don't know, haven't seen any other than special functions meter where the needle shows a very specific variable.

Now, you shouldn't measure amps with a cheapo meter in a high energy setup as it can blow, that's for any meter, analog or digital.

There's a small cheap cool clamp that does dc current with a very low range, i think it is a uni-t, my experience with the band isn't great but if you are after the functions it has its kind of hard to beat...

JS

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Offline Kleinstein

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Re: Do multimeters measure ACA
« Reply #5 on: July 12, 2018, 05:59:07 pm »
Some of the very cheap meter do not measure ACA - these usually also miss a low ranges for AC voltage. With analog meters (without power supply) the rectifier for low AC voltages is difficult and not very accurate. They usually had a 2 nd slightly nonlinear scale for AC.

Especially the pocket size meters sometimes do no offer current measurement at all.


Not having a current range or not having ACA an the cheap meters can also be good, as it means you are not temped to use is with mains current.
 

Offline JS

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Re: Do multimeters measure ACA
« Reply #6 on: July 12, 2018, 11:17:28 pm »
Some of the very cheap meter do not measure ACA - these usually also miss a low ranges for AC voltage. With analog meters (without power supply) the rectifier for low AC voltages is difficult and not very accurate. They usually had a 2 nd slightly nonlinear scale for AC.

Especially the pocket size meters sometimes do no offer current measurement at all.


Not having a current range or not having ACA an the cheap meters can also be good, as it means you are not temped to use is with mains current.
They could used a dual coil ac meter, they do work for DC and don't need rectifiers, but it's also true that they not always do that...

JS

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Offline schmitt trigger

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Re: Do multimeters measure ACA
« Reply #7 on: July 12, 2018, 11:39:16 pm »

Not having a current range or not having ACA an the cheap meters can also be good, as it means you are not temped to use is with mains current.

Amen! Get yourself an AC clamp.
So I also recommend that is is far better to use a clamp meter.

The nice fact is that the clamp can be also used with a digital scope (with the banana to BNC adaptor) and actually see the current waveform.
In the scope, you can display simultaneously peak, RMS, average, and many other measurements that are impossible to make with a simple meter.

Besides, many AC appliances will draw an inrush current which is several times its rated current. That inrush could only last a semicycle like an electronic load without inrush limiting, or could last several seconds like a motor starting under heavy load. Inrush current cause all sorts of problems, and the scope will faithfully capture it.

An added bonus is if the clamp is the hall effect type, you'll also be able to read DC current safely.
 


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