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Old 06-05-2022, 01:42 AM   #1
caspian
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Default Can Ammeter damage Power Supply?

Dear Members,

My DC linear Lab Power Supply does not display the current and voltage correctly. Thus, I am going to connect an Ammeter/Voltmeter Module to the DC output of the power supply. Then, a load will be connected the takes about 1-5volts with 0.1-1.5Amps.
But I heard If I connect an Ammeter to the output of the power supply, then the Ammeter module is not isolated from the power supply so that the Ammeter can damage the power supply.
Is this true?

Thanks

I have attached the photo of a sample Ammeter module that I am going to buy. I have attached a photo of my power supply too.
Power Supply: 15v 2A Variable Linear DC
Ammeter/Voltmeter: 100v 10A DC
Attached Images
File Type: jpg power1 - Copy.jpg (1.10 MB, 15 views)
File Type: jpg ammeter.jpg (162.3 KB, 16 views)

Last edited by caspian; 06-05-2022 at 02:33 AM..
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Old 06-05-2022, 05:02 AM   #2
RukyCon
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Default Re: Can Ammeter damage Power Supply?

I've used those displays before, and they do not have to run on a isolated supply, in fact, the ground wire for the display power is commoned to the current shunt ground, so if you do try to use an isolated supply, then both supplies will end up having a common ground, thus end up not being isolated. Some listings for these will also show them getting powered by the same supply they're reading from (attached below is one such image i found).
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File Type: jpg HTB1XcVuN9zqK1RjSZPxq6A4tVXa8.jpg (110.3 KB, 12 views)
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Old 06-05-2022, 05:21 AM   #3
stj
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Default Re: Can Ammeter damage Power Supply?

you cant read voltages below the operating threshold like that,
the meter power will have to be tapped from some other place in the psu
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Old 06-16-2022, 07:00 AM   #4
caspian
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Default Re: Can Ammeter damage Power Supply?

I am going to provide a separate power to the Ammeter/Voltmeter module from an AC power adapter. (see the picture)
The power adapter is completely separate from the linear power supply, except for their ground.
I want the Ammeter/Voltmeter module to be able to measure all voltages from 0v to 15v and all currents from 0A to 5A, specifically the values near 0.
Now I have got a question:
What voltage and current should the power adapter provide for the Ammeter/Voltmeter module so that the Ammeter/Voltmeter module be able to measure all voltages from 0v to 15v and all currents from 0A to 5A?
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File Type: jpg ammeter2.jpg (49.0 KB, 8 views)

Last edited by caspian; 06-16-2022 at 07:16 AM..
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Old 06-19-2022, 03:55 AM   #5
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Default Re: Can Ammeter damage Power Supply?

This depends on the meter module to what voltage it will work at
Now some meter modules can be modified to work on a separate power supply I have done this personally before but not all can be done easily the smaller the meter module the harder this procedure is to be done

Now some have it where the voltage meter inputs are isolated but not the current sensing especially if it has the dual display

If you want to have a isolated current module you need to get a meter module that has a 5 input and states that it is isolated however if go this route the shunt has specifications like 75 mil volts for a 100 amp shunt and you would have to a scale for what each mil volt means for amp of current

Now there is another option for dc voltage/current and it is a external amp current pickup sensor
I would caution you that if you go this route the quality of these units are not always good what I mean is that sometimes the actual current draw is not what is displayed some of them you adjust the meter for accuracy but be aware not all of them have this option —> this is extremely hard to find

This meter module might be what you are looking for

https://www.ebay.com/itm/27486669262...id=23033951229

This shows you how to hook up the the meter module

https://i.ebayimg.com/images/g/Gq8AA...TQ/s-l1600.jpg

One note the minimum voltage for this setup is 8 volts to a maximum of 12 volts

This type of meter module is hard to find

I have not personally use this exact module before I found this type when looking for the other type that I mentioned earlier but I am going to buy a couple of them and try them
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Last edited by sam_sam_sam; 06-19-2022 at 04:34 AM..
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