DC current

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Old 09-02-18, 09:05 AM
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DC current

I would like to know if I can use an AC amp meter to check DC current up to 300 amps. my meter is rated for 300 amps AC, I have read that it possible to do this. However I would more info about the subject before trying this.
 
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Old 09-02-18, 09:14 AM
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Welcome to the forums.

As far as I know.....an AC ammeter will not read DC amperage properly.
The clamp-on probes work by measuring the magnetic strength across the wire. AC has a an alternating magnetic field while DC does not. A DC clamp meter usually uses a Hall effect transistor.

You can purchase a DC shunt that will indicate the DC amperage as a DC voltage that any DC voltmeter can read. This shunt is installed in series in one of the power legs.
https://www.google.com/search?client...w=1067&bih=511
 
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Old 09-02-18, 05:10 PM
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AC amp meter will not read DC current at all. Theoretically it should read 0A with AC current meter, but in reality it will read very low current which is a result from the noise on DC circuit.

You will need a shunt as PJmax suggested. It is basically a high current resistor with low resistant. You will be measuring the voltage across a shunt and since you know the resistance of the shunt, you can calculate the current using ohm's law.
 
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Old 09-03-18, 04:53 AM
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A DC clamp on ammeter is available but they are more costly than an AC only type.


There are many places to purchase these.
Shop around it interested.
 
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Old 09-03-18, 05:40 AM
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DC Clamp meter is not recommended for anything requiring accurate reading or permanent installation.
Because DC Clamp meters use hall effect, it is very sensitive to nearby magnetic field and even Earth's magnetic field affects it. All DC clamp meters require zero before measuring for this reason.
 
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Old 09-03-18, 06:28 AM
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Originally Posted by lambition View Post
DC Clamp meter is not recommended for anything requiring accurate reading or permanent installation.
Because DC Clamp meters use hall effect, it is very sensitive to nearby magnetic field and even Earth's magnetic field affects it. All DC clamp meters require zero before measuring for this reason.
Funny you mention this. I recently tested a Sentran (non-split core) 20Amp hall effect for 60Hz mag field resistance. It was solid to 100A/m field strength on all axis.
Cheap clamp-on/split cores may be a different story.
 
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