Using RTD's for Motor Protection
Using RTD's for Motor Protection
(OP)
I got a new motor from a respectable manufacturer with RTD's for measure and protect the windings from Over-temperature. I was surprised to see that the RTD’s are three wires, with the compensation wire connected to the ground and does not have any terminal.
Wondered: is it normal to measure the motor temperature with only two wires RTD? My feeling is that the error might be higher then the set point. Thanks to all.
Wondered: is it normal to measure the motor temperature with only two wires RTD? My feeling is that the error might be higher then the set point. Thanks to all.





RE: Using RTD's for Motor Protection
two/three/four wire use has more to do with lead compensation. you can always zero out(calibration) the lead resistance even with two wire setups.
RE: Using RTD's for Motor Protection
RE: Using RTD's for Motor Protection
Also read up a little on measurement with RTD's under "OMEGA" i.e., Omega Engineeering, it provides lot of valuable technical information, free of charge.
RE: Using RTD's for Motor Protection
Only 3/4 wire setups have compensating leads.
Where i work we use rtd's and thermocouples and input these to SMART temp.transmitters, this way we don't need to worry about cold junction or about compensating leads as we mount the transmitters as close to the process measurement as possible.