Generator RTD reading difficulties

[Gentest]

I am having a strange noise(?) problem with measuring some 3-wire 10-ohm copper RTDs installed in a generator. When the generator is not running, the rtds read fine, but when the generator is running, the stator winding rtds read noisily, but the bearing rtds read fine. I am using shielded wire from the rtd terminal box to my datalogger. The stator RTDs flucuate +/- 10-20 deg C from reading to reading. I have switched cards in the data logger, grounded one leg of the RTD, moved the ground on the shield wire, all with no effect. I have discussed this with the datalogger manufacturer and they have no solution for me. Has anyone encountered this problem before?

 

[byrdj]

its been a long time, but i recall fusable grounding disk on the terminal strip, just behind the terminal screws and if thet were not there having problems with pen recorder

 

[ScottyUK]

A rogue ground connection somewhere at the field end? There should only be a ground for the shield at the quiet end (i.e. chart recorder, DCS, etc). Check the RTD itself for a ground as well as the screen.


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