Alarm Drop

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.

If NO:

  1. Display and record TC readings and median exhaust temperature (TTXM)
  2. Locate thermocouple number that represents the lowest TC (in spread calculation) and note location.
  3. Record Spread 1 (TTXSP1) and Spread 2 (TTXSP2)
  4. Record allowable spread (TTXSPL) and compressor discharge temperature (CTD)
  5. Record alarm messages

Note, combustion monitor spreads are determined in SEQ_TRB2, Rung -86.

If defective TC, replace faulty TC at first opportunity.