PR55-20A Predictive Maintenance Sensor not reading AC Current

Hello, I have a PR55-20A sensor I’ve purchased for testing at my company but unfortunately I’ve been unable to get a reading for the current. All of the other data is coming in properly.

I have tried it on 110v and 230v lines. I have also reset the sensor, checked the wires and all seems fine. The connection to the circuit board is solid.

Please help, this is a pretty big project. If I can get this sorted out we’ll be deploying quite a few of them.


Hi Jeff,
I will recommend checking two things

  1. make sure the current sensor is wrapped around either hot or neutral line. not both. else the electric field will get cancelled and you will always get zero.

  2. the minimum current it reads is 1.5Am. ) we can make a version which can read low current but then we wont be able to read all the way 100Amp)

let me know if you have any questions.


Thanks Bhaskar! I guess I should have probably known that. I was just clamping the sensor to the power cable, I didn’t know the wire had to be separated. I did so and it’s working perfectly.

Hello Bhaskar! Here is more info on my issue:

The motor is 480V 3 phase. We checked the sensor output with a meter and it is putting out a pretty steady 17 milliamps.

I have shielded both the box with copper shielding tape and the ac sensor wire with 3M mesh electrical shielding tape. The mesh has been grounded to the machine.

Larger 868 - 900 Mhz antennas were added to both the modem and the sensor.

Like before, when the machine was not running I was getting broadcasts of both temperature and vibration data. As soon as it was powered up the transmissions stopped.

Is there a better split-core ac sensor we could try perhaps? One of the electricians concerns were that the output of the sensor was too high for the unit, but that was just a theory.

Any help would be greatly appreciated! Thank you.

Hi Jeff,
can you share your address with
I will send you a demo unit to run some quick tests.