The reading of the PT100 platinum thermistor is unstable
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A PT100 thermistor is used to measure the temperature at the top of the recovery tower in the MTBE processing unit; its measurement range is 0–150°C. The displayed value fluctuates greatly, while the resistance values measured both in the control cabinet and on-site remain stable, at 140 ohms for AC and BC, and 7 ohms for AB. There are no issues with the wiring or the safety barrier. Upon examining the thermometer, it was found that there was obvious damage in the front section of the inner shielding tube, and water was present inside the outer shielding tube. Why then are the resistance values stable when measured with a multimeter, but the DCS display shows large fluctuations? Seeking advice from experts
Water accumulation inside the sleeve may be caused by fluctuations resulting from grounding.
This post was last edited by xxkhc on 2020-8-23 at 19:53. It seems that multiple edits were made, resulting in three identical replies; therefore, the content of this post has been deleted.
This post was last edited by xxkhc on 2020-8-23 at 19:52. It seems that two identical replies were created by accident, so the content of this post has been deleted.
This post was last edited by xxkhc on 2020-8-23 at 19:54. It seems that multiple edits were made, resulting in three identical replies; therefore, the content of this post has been deleted.
Please measure the insulation resistance of the platinum resistor with respect to ground; it’s possible that it is grounded, which is causing interference.
Test the insulation resistance between the lead and the thermistor housing; is the end of the thermistor damaged?
Then it’s not a problem with the thermal resistor; there is interference from the cable, or go to the cabinet room to check the safety barrier directly
Please measure the insulation resistance of the platinum resistor with respect to ground; it’s possible that it is grounded, which is causing interference