Checking total Amps 24DC

All,

I have a 24VDC/10A Power supply feeding a bunch of sensors and field devices.

Since I don't know the total Amps already being used by their documentation, can I check the total ohms by disconnecting the PS and then use Ohms law to figure out the total A? I know you can't do this on AC systems because inductance.



Thanks!

Fluke makes a few DC clam-on meters... why not use something like that?

scott.lawrence said:

Fluke makes a few DC clam-on meters... why not use something like that?

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No power to turn the line on right now.

if the power input of these devices were simple resistances or coils probably measuring the resistance could work, but most now days devices have internal non-linear switching power supplies, for example those that allow a wide range of input voltage, then to measure resistance and apply Ohm law will not work.

The only solution for me is to connect a 24DC source and measure the intensity.

Apart from the above, if there are incandescent lamps the resistance measure can also be very inaccurate since they have much less resistance when they are cold.

You can start by using the device data to do a load calculation. Most suppliers give numbers that are worst case, so it should give you some indication of what the total demand on the PS will be.

Put the Fluke in Amps mode, and put in series with the +24 line. Red to supply, black to load.

Annaa said:

may be the power input of these devices were simple resistances or coils probably measuring the resistance could work,do you think so.

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No. See post #4.
Connecting the Fluke is easy. I don't understand why we're looking for a harder way to do it.

keithkyll said:

No. See post #4.
Connecting the Fluke is easy. I don't understand why we're looking for a harder way to do it.

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Because the OP said this in post #3

Timeismoney08 said:

No power to turn the line on right now.

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