RTD drifting in AB 1746-NR4 module


Thread Starter

John Marvin

I have an Allen Bradley 1746-NR4 module installed in our system per manual's specs but I am seeing RTD drifting at temperatures above 150F. It will drift as much as 15F. Is there anything special that I can do to fix this? The RTD wire appears to be ok because when we wire it to a 4-20mA transmitter, we don't see the drifting problem.

I've replaced this module already with no success. There's a couple VFDs and starters in the same panel in the panel but it's about 2.5' away so I don't know if there's any EMF or something similiar. The RTD cables are routed away from any motor leads.

Bill Clemons

You might consider adding another wire to the RTD for better resolution of the sensor resistance.