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We are operating GE Frame 6581B gas turbine on natural gas, liquid fuel as emergency fuel, TMR, simple cycle operation.
Recently our control system migrated Mark V to Mark VIe. After migration, unit was started several times without any problems.
Last startup on gas fuel unit tripped on STOP/SPEED RATIO VALVE POS ERRROR TRIP (L3GRVT), just after firing, all the flame was established.
Logic is if SRV Position Feedback FSGR is greater than 5% for 5 Sec before the warmup period unit will trip.
We observed that intermediate valve pressure FPG2 is increased to 19 Barg (261 PSIG)
TNH- Turbine speed %
FPG2- Intermediate Valve Pressure Barg
FAGR_NVR- Servo current from <R>
<pre>
TNH-----FPG2-------FAGR_NVR--- FAGR_NVT--- FAGR_NVS
20.15----2.09-------(-)0.26--------(-)0.57------(-)4.03
20.52----3.70------ (-)35.25---------8.56--------14.29
21.75---10.06-------(-)71.34---------31.19-------32.35
22.92---19.75-------(-)81.77---------27.34-------22.92
</pre>
(TNH*2.508)-11.8= FPRGOUT
(Speed * Fuel Gas pressure ratio control gain )- Fuel gas pressure ratio control off set =SRV servo command
After several hours of investigation we found that one <R> core FPG2 transmitter not reading the pressure, it always reading zero. (We have 3 intermediate valve pressure transmitters 96FG-2A/2B/2C and one upstream pressure transmitters FGUP)
We replaced the faulty transmitter and unit started successfully.
96FG-2A/2B/2C terminated in TBQB <R> and from there it is connected to MVRA card ( in Mark V it was TCQA)
My question is if one transmitter failure unit will trip?
Then where is the redundancy? Voting?
Or something wrongly configured during the Mark V to Mark VIe migration.
Migration we used all the old terminal boards, TCQC cards.
Kindly give your valued comments.
Recently our control system migrated Mark V to Mark VIe. After migration, unit was started several times without any problems.
Last startup on gas fuel unit tripped on STOP/SPEED RATIO VALVE POS ERRROR TRIP (L3GRVT), just after firing, all the flame was established.
Logic is if SRV Position Feedback FSGR is greater than 5% for 5 Sec before the warmup period unit will trip.
We observed that intermediate valve pressure FPG2 is increased to 19 Barg (261 PSIG)
TNH- Turbine speed %
FPG2- Intermediate Valve Pressure Barg
FAGR_NVR- Servo current from <R>
<pre>
TNH-----FPG2-------FAGR_NVR--- FAGR_NVT--- FAGR_NVS
20.15----2.09-------(-)0.26--------(-)0.57------(-)4.03
20.52----3.70------ (-)35.25---------8.56--------14.29
21.75---10.06-------(-)71.34---------31.19-------32.35
22.92---19.75-------(-)81.77---------27.34-------22.92
</pre>
(TNH*2.508)-11.8= FPRGOUT
(Speed * Fuel Gas pressure ratio control gain )- Fuel gas pressure ratio control off set =SRV servo command
After several hours of investigation we found that one <R> core FPG2 transmitter not reading the pressure, it always reading zero. (We have 3 intermediate valve pressure transmitters 96FG-2A/2B/2C and one upstream pressure transmitters FGUP)
We replaced the faulty transmitter and unit started successfully.
96FG-2A/2B/2C terminated in TBQB <R> and from there it is connected to MVRA card ( in Mark V it was TCQA)
My question is if one transmitter failure unit will trip?
Then where is the redundancy? Voting?
Or something wrongly configured during the Mark V to Mark VIe migration.
Migration we used all the old terminal boards, TCQC cards.
Kindly give your valued comments.