Control.com - Nerds in Control

Following diagnostic alrams have appeared in Mark V in Frame 6 gas turbine control while unit was in operation.

Alarm ID  Core	  Message
D2839	  C	  Voter mismatch,<T>L4ETR2
D2838	  C	  Voter mismatch,<T>L4ETR1
D2827	  C	  Voter mismatch,<T>L12H_P
D1697	  R	  TCE1 TMR check trouble,ETR2
D1713	  T	  TCE1 Loopbak , solenoid, 
                  ETD1/SOL1/MTSV  
D1697	  T	  TCE1 TMR check trouble,ETR2
D1696	  T	  TCE1 TMR check trouble,ETR1
D1697	  S	  TCE1 TMR check trouble,ETR2
D1696	  S	  TCE1 TMR check trouble,ETR1
D1696	  R	  TCE1 TMR check trouble,ETR1

The above alarms are still persisting.
Logic       Voted      R          S           T           

 L4ETR1       1        1           1           0            

 L4ETR2       1        1           1           0

 L12H_P       0        0           0           1

Pl suggest remedial measures.
Thanks

The reason the ETRn (Emergency Trip Relay) voting mismatch Diag. Alarms are being annunciated is because <T> has detected an HP (turbine shaft speed) over-speed--L12H_P.

You can use Pre-Vote Data Display to view TNH_OS to see if the speed signal input to <T> is stable or is low or fluctuating/intermittent. If it's okay, then it might just have been an intermittent problem, which can usually be "cleared" with a Master Reset.

If the speed input to <T> is bad or intermittent, you will need to check the wiring and the speed pick-up, verify the speed pick-up gap, etc. before replacing the TCEA card in Loc. 5 of <P>.

Please write back to let us know how the problem is resolved.

We had checked the TNH_OS inputs in Prevote data display for T computer. The input to T was stable.

Subsequently we have rebooted T computer with machine on line and all diagnostic alarms got resetted. Presently there are no alarms.
Thanks for the help.

Regards

Veenak

Veenak,

Thanks for the feedback!

I missed to share some information.

Before rebooting the T computer , it was noticed that K6 and K9 relays on TCTG card <P> core for ETR1 and ETR 2 were in dropped condition and LEDs on TCEA card <Z> were not in synchronism with other TCEA cards for <X> and <Y>.

Thanks

Regards
Veenak

Exactly what one would expect to see. The overspeed detected by <Z> drops out the ETRs, and the LEDs indicate a mismatch with <X> and <Y>--which is just what the Diagnostic Alarms indicated.

Any time you see LEDs blinking out of synchronism with others of the same type, that indicates the card has at least one Diagnostic Alarm.

Thanks

Regards
Veenak