2x1 Combined Cycle, 7FA/D11 with Marke 6e (Mark5 migration)
While checking exhaust temperature thermocouples we found that all readings on one unit are low ~20 Deg F. We disconnect the Thermocouple at the Mark6e input card (TBQA) and inject 1000 Deg F with a simulator and get readings of 980 Deg F. I suspect an error with cold junction compensation since all the readings are low ~20 Deg F. On another unit we get the expected 1000 Deg F reading.
Both units show close cold junction values (2 different locations) around 78 Deg F.
I'm not sure, but it looks like the cold junction compensation is done on the terminal board, TBQA. So I may change that but wanted to ask to see if anyone has seen this?
While checking exhaust temperature thermocouples we found that all readings on one unit are low ~20 Deg F. We disconnect the Thermocouple at the Mark6e input card (TBQA) and inject 1000 Deg F with a simulator and get readings of 980 Deg F. I suspect an error with cold junction compensation since all the readings are low ~20 Deg F. On another unit we get the expected 1000 Deg F reading.
Both units show close cold junction values (2 different locations) around 78 Deg F.
I'm not sure, but it looks like the cold junction compensation is done on the terminal board, TBQA. So I may change that but wanted to ask to see if anyone has seen this?