DC Current Sensor Output Too High on 120A Pump

Hi everyone,
We’re using two of the ATO DC hall effect current sensors, 200A (SKU: ATO-CUS-DC1500), on our solar-powered irrigation systems.

One has been installed for a few months on a pump pulling around 90A DC. It works great and outputs about 13mA (as expected).
However, I recently installed the second one on a larger solar pump that draws ~120A, and it’s consistently outputting too much — 50mA yesterday, which doesn’t make sense.

To troubleshoot, I swapped the working sensor from the smaller pump onto the larger pump’s DC line. That one showed 35mA, even though my clamp meter read a steady 119A. Yesterday I also ordered the 300A version of the sensor, just in case it’s a range issue.

Any ideas what might be causing the inflated output on the 200A current sensor?

Sable wrote:Hello, Sable
Thanks for your question.
Please confirm whether you adjusted the zero potentiometer after installation. The sensor should read 4mA when power is applied, but no current is flowing.
When you moved the working sensor from the 90A pump to the 120A one, was the change in output relatively linear? If not, it may suggest a non-functional unit.
If the output is as high as 50mA, we suggest double-checking the wiring. The output should be stable if the sensor is functioning correctly.
Let us know if you still have issues after these checks.

Sable wrote:Sable, did you try adjusting the span after fixing the zero?
If the span potentiometer does nothing, even when rotated fully, then yeah — it might be burned out. I’ve had that happen once when I miswired the input side. The sensor still “worked,” but the output was crazy and wouldn’t respond to span changes.

Thanks for the tips, everyone.
I re-checked the zero point today and found it at 3mA, so I adjusted it to 4mA. Now it reads 92mA on the output — way beyond what I expect. I tried turning the span pot from left to right, and it had zero effect. That seems to confirm that the sensor is probably damaged. I’ll just order another unit.

Sable wrote:We appreciate your understanding and are here to help with your future installations. If you need further guidance with the 300A version you ordered, don’t hesitate to contact us.
Have a great day!