LEM LA 55-P

Hi There,

I am trying to figure out how to interface this current transducer with the arduino. I am supplying dual rail voltage +12V -12V, and I have a 100 ohm resistor on the M, going to the arduino/Multimeter.

I then am just trying to read the raw analog value right now on the arduino, and I am getting only "14" as the number that is coming from it. I am running 1-8A through it.

I also tried reading mV on a multimeter and I get 0, no matter if I kill the power or run current through it. I am at a complete loss because I should be getting mV at the very least.

I have a variac then it goes to a terminal block, then through the transducer, then to the load.

Has anyone got any experience with these and what I could be missing?

Thank you for any help. I've spent hours trying to figure this out, at the very least why I am not getting mV/mA

inventrex3601:
I also tried reading mV on a multimeter and I get 0, no matter if I kill the power or run current through it. I am at a complete loss because I should be getting mV at the very least.

You have a multimeter that reads millivolts AC? :astonished:

HI,

You must connect the 100 ohm to the ground of the two supplies, then read across the 100 resistor.

Also you can increase the apparent primary current by running the primary wire through the center hole more than once. You should expect the sensor to multiply the output by the number of passes through the primary wire. So 3 passes and 5V will look like 15 amps.

The output will be AC so you may have trouble sensing it with a multimeter. Also I have a similar part and there is an offset when the primary has Zero current.

Try connecting the 100 ohm to the ground of the 2 supplies.
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