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Hi everyone.
At our site we have a GE 9FA gas turbine with MARKVIe control system. I have a few questions regarding thermocouples connected to the MARKVIe.
Thermocouples work on the principle of Seeback effect and they produce output in mV.
Now my question is
1) the thermocouple junction at the field end (hot junction) is supposed to be referenced to zero so that it can be measured with respect to the reference table for say K-type thermocouple.
But the cold junction in reality is at the terminal end of the JB or at the MARKVIe card which is exposed to ambient and not zero degrees. Now how is the temperature compensated or cold junction compensated for the ambient temperature?
2) How is the ambient temperature measured for cold junction compensation at GE MARKVIe?
3) If the erection team by mistake wire the thermocouple cable from JB to MARKVIe using a different material other than the material of K-type how do we identify? (irrespective of the color code of the wire)
Please reply so that it would be very useful for everyone.
At our site we have a GE 9FA gas turbine with MARKVIe control system. I have a few questions regarding thermocouples connected to the MARKVIe.
Thermocouples work on the principle of Seeback effect and they produce output in mV.
Now my question is
1) the thermocouple junction at the field end (hot junction) is supposed to be referenced to zero so that it can be measured with respect to the reference table for say K-type thermocouple.
But the cold junction in reality is at the terminal end of the JB or at the MARKVIe card which is exposed to ambient and not zero degrees. Now how is the temperature compensated or cold junction compensated for the ambient temperature?
2) How is the ambient temperature measured for cold junction compensation at GE MARKVIe?
3) If the erection team by mistake wire the thermocouple cable from JB to MARKVIe using a different material other than the material of K-type how do we identify? (irrespective of the color code of the wire)
Please reply so that it would be very useful for everyone.