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Raised stator winding temperature on GT MARK-II indicator was observed. 3 wire copper-10 RTDs installed on stator and cooling air path.

All RTDs have two separate positive and negative and a common compensation cable. But when we measured RTD temperature from JB5 it was less then what was being displayed e.g.

        JB(RTD Disconnected)     MARK-II TI
RTD-1   103degC                  100degC
RTD-2   103degC                  115degC
RTD-3   101deGc                  103degC
RTD-4   104DegC                  118DegC
and so on

We replaced positive and negative cable of RTD-4 from JB to MARK-II control MARK-II indicator started displaying 100DegC.

Now my question is why all RTDs which are in error showing positive shift of temperature only??? why not negative?? all cables are equally old and they are a part of common jigg. I am only confused due to this positive increment of temperature and same is the case with our other GT. Thanks in anticipation.

Regards,
Adeel Imtiaz

calibrate your GT temp:indicator as per copper-10 vs temp: standards graph.

How are you measuring the RTD temp. at the JB? What are you using in your MKII panel to display your Stator winding temps?

Many Mk-II-equipped units used interconnecting cables with pinned-and-socketed connectors on one or both cable ends. These are subject to corrosion if they were not properly tightened during original construction--and many weren't. Also many cable vaults/pits have been found to be filled with water and/or lube oil and the vapors are drawn into properly air conditioned compartments and can also contribute to corrosion.

You didn't indicate the results of checking the resistances of the individual conductors. You will likely find, after consulting an RTD table, that temperature indications increase with increasing resistance and so if there is increased resistance from conductors and/or corroded pins & sockets the indicated temperature will be abnormally high.