Alarm Drop #123 – Exhaust Thermocouple Trouble
(alone – no other Combustion Monitor Alarms)
Signal Name: L30SPTA
CSP Derivation: SEQ_TRB2, Rung -190.6
Alarm occurs when the difference between the highest and lowest TC is greater than 5x (five times) the internally calculated Combustion Monitor Allowable Spread.
Check for Smoke!
If YES: initiate trip.
- Display and record TC readings and median exhaust temperature (TTXM)
- Locate thermocouple number that represents the lowest TC (in spread calculation) and note location.
- Record Spread 1 (TTXSP1) and Spread 2 (TTXSP2)
- Record allowable spread (TTXSPL) and compressor discharge temperature (CTD)
- Record alarm messages
Note, combustion monitor spreads are determined in SEQ_TRB2, Rung -86.
If defective TC, replace faulty TC at first opportunity.