RTD Temperature spikes

[EETS]

Has anyone found a way to eliminate temperature spikes on motor RTD's to keep from tripping out motor protection relay. The relay has no way to add a time delay to filter out spikes.

 

[ScottyUK]

What causes the spikes? Once you understand the cause the cure is easier to suggest.

 

[EETS]

All conductors and connections have been checked and I've ohmed the rtd's and they look good. I'm guessing it is some electrical noise? I have also move the rtd conductors to different inputs to see if rtd fault shows up on on new input/channel.

 

[itsmoked]

Best would be to put a scope across the RTD to see how big the spikes are and what frequency they are. Also if they're periodic or event driven.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[mesutphen]

We had a problem with our boiler feed pumps shutting down on a spurious excessive vibration. Eventually, we traced it down to whenever an operator keyed a radio near the pump, it caused a spike in the vibration signal. We bought shielded cable and no longer have this problem.

It sounds to me like you have some electrical noise. Buy some shielded cable. It's more expensive, but worth it in my opinion.

 

[EETS]

Thanks Mesutphen,

We have shielded cable with it grounded at the URTD II module input as directed by the manufactuer. It is floating at the motor side ( The Shield).

 

[danw2]

Check out the discussion thread here:

http://www.control.com/thread/1342151431