R
Dear all,
Frame 6FA, TMR MKVI panel, liquid fuel MNQC, LFBV feedback flow divider magnetic pick up, water injection for NOx reduction, IGV in temperature control, DROOP governor mode, no IBH, no air intake coolers, exhaust to HRSG. Combined cycle operation. Power generation application.
IGV controlled by VSVO in SLOT7. RegType 2_LVposMAX. Mon1: csgv_a, Mon2: csgv_b, Reg3_Fdbk: csgv. ServoOutput3:cagv.
Major inspection in January 2016 conducted by OEM.
Unit running without apparent problems till last week.
21:49:17.547 <R> SLOT 7 VSVO Diagnostic alarm.
21:49:17.547 <S> SLOT 7 VSVO Diagnostic alarm.
21:49:17.547 <T> SLOT 7 VSVO Diagnostic alarm.
Found diagnostic fault code 40 "LVDT # RMS voltage out of limits" active in <R>, <S> and <T>.
No prior process or diagnostic alarms.
21:53:09.101 L30TXA_ALM "EXHAUST TEMPERATURE HIGH".
21:53:09.258 L86TXT_ALM "EXHAUST OVER TEMPERATURE TRIP".
Prior to trip unit stable at part load (60 MW). All parameters stable.
After diagnostic alarm was annunciated, trends show quick oscillations of IGV control servo current (cagv) and IGV angle (csgv ranges from 63º to 90º rapidly during incident). Maximum exhaust thermocouple reading reaches 1275 ºF. No record of TTXM but must have gone higher than TTRXB tripping the unit.
After trip, found faulty LVDT1 with bore full of dust. Seems as if the core of the LVDT was displaced and was "rubbing" the bore. Changed LVDT1 and unit is running again without apparent problems.
Anyone has experience with LVDT feedback going high instead of low?
My concern now is if there is a remote possibility to have sudden IGV closing due to IGV feedback going high taking the compressor to a surge event before tripping the unit.
Tried monitoring in Toolbox LVDT1 and LVDT2 feedbacks csgv_a and csgv_b, but with the unit running they show 0. Is there any way to read value of each LVDT independently?
Thanks in advance.
Frame 6FA, TMR MKVI panel, liquid fuel MNQC, LFBV feedback flow divider magnetic pick up, water injection for NOx reduction, IGV in temperature control, DROOP governor mode, no IBH, no air intake coolers, exhaust to HRSG. Combined cycle operation. Power generation application.
IGV controlled by VSVO in SLOT7. RegType 2_LVposMAX. Mon1: csgv_a, Mon2: csgv_b, Reg3_Fdbk: csgv. ServoOutput3:cagv.
Major inspection in January 2016 conducted by OEM.
Unit running without apparent problems till last week.
21:49:17.547 <R> SLOT 7 VSVO Diagnostic alarm.
21:49:17.547 <S> SLOT 7 VSVO Diagnostic alarm.
21:49:17.547 <T> SLOT 7 VSVO Diagnostic alarm.
Found diagnostic fault code 40 "LVDT # RMS voltage out of limits" active in <R>, <S> and <T>.
No prior process or diagnostic alarms.
21:53:09.101 L30TXA_ALM "EXHAUST TEMPERATURE HIGH".
21:53:09.258 L86TXT_ALM "EXHAUST OVER TEMPERATURE TRIP".
Prior to trip unit stable at part load (60 MW). All parameters stable.
After diagnostic alarm was annunciated, trends show quick oscillations of IGV control servo current (cagv) and IGV angle (csgv ranges from 63º to 90º rapidly during incident). Maximum exhaust thermocouple reading reaches 1275 ºF. No record of TTXM but must have gone higher than TTRXB tripping the unit.
After trip, found faulty LVDT1 with bore full of dust. Seems as if the core of the LVDT was displaced and was "rubbing" the bore. Changed LVDT1 and unit is running again without apparent problems.
Anyone has experience with LVDT feedback going high instead of low?
My concern now is if there is a remote possibility to have sudden IGV closing due to IGV feedback going high taking the compressor to a surge event before tripping the unit.
Tried monitoring in Toolbox LVDT1 and LVDT2 feedbacks csgv_a and csgv_b, but with the unit running they show 0. Is there any way to read value of each LVDT independently?
Thanks in advance.