Greetings all,
We have a gas turbine MS 5001PG (Mark 5).
During normal operation, it was loaded with 10MW.
Firstly, a diagnostic alarm:<pre>
P DROP DESCRIPTION
S 1340 TCQA LVDT Position Diff. High Reg#5
R 1340 TCQA LVDT Position Diff. High Reg#5
T 1340 TCQA LVDT Position Diff. High Reg#5</pre>
Then the turbine tripped on the alarm:<pre>
P DROP DESCRIPTION
Q 0141 INLET GUIDE VANE CONTROL TROUBLE TRIP</pre>
We did the following:
- Check the solenoid coils of servo valve by measuring the resistance of each one. All 1 kilo ohms: OK
- Check the IGV filter: OK
- Check the excitation and the feedback of the LVDT: found them at the range of 0.7V @ 42deg (Min. angle of IGV) - 3.5V @ 85deg (Max. angle of IGV)
- Tried to manually stroke for IGV from 42deg -> 85deg, its feedback at the control was OK and the IGV was at the position (We physically checked it).
The turbine was ready to start, so we started it up again. It ran for about 30min at 4.5MW load. IGV was at the required position (56deg) and the actual position was:<pre>
<R> core -> 55.9
<S> core -> 55.59
<T> core -> 55.91</pre>
After 30min of normal operation, the same diagnostic alarms occurred again:<pre>
P DROP DESCRIPTION
S 1340 TCQA LVDT Position Diff. High Reg#5
R 1340 TCQA LVDT Position Diff. High Reg#5
T 1340 TCQA LVDT Position Diff. High Reg#5</pre>
and the turbine tripped after 10min on the alarm:<pre>
P DROP DESCRIPTION
Q 0141 INLET GUIDE VANE CONTROL TROUBLE TRIP</pre>
What is the cause of the trip?
We have a gas turbine MS 5001PG (Mark 5).
During normal operation, it was loaded with 10MW.
Firstly, a diagnostic alarm:<pre>
P DROP DESCRIPTION
S 1340 TCQA LVDT Position Diff. High Reg#5
R 1340 TCQA LVDT Position Diff. High Reg#5
T 1340 TCQA LVDT Position Diff. High Reg#5</pre>
Then the turbine tripped on the alarm:<pre>
P DROP DESCRIPTION
Q 0141 INLET GUIDE VANE CONTROL TROUBLE TRIP</pre>
We did the following:
- Check the solenoid coils of servo valve by measuring the resistance of each one. All 1 kilo ohms: OK
- Check the IGV filter: OK
- Check the excitation and the feedback of the LVDT: found them at the range of 0.7V @ 42deg (Min. angle of IGV) - 3.5V @ 85deg (Max. angle of IGV)
- Tried to manually stroke for IGV from 42deg -> 85deg, its feedback at the control was OK and the IGV was at the position (We physically checked it).
The turbine was ready to start, so we started it up again. It ran for about 30min at 4.5MW load. IGV was at the required position (56deg) and the actual position was:<pre>
<R> core -> 55.9
<S> core -> 55.59
<T> core -> 55.91</pre>
After 30min of normal operation, the same diagnostic alarms occurred again:<pre>
P DROP DESCRIPTION
S 1340 TCQA LVDT Position Diff. High Reg#5
R 1340 TCQA LVDT Position Diff. High Reg#5
T 1340 TCQA LVDT Position Diff. High Reg#5</pre>
and the turbine tripped after 10min on the alarm:<pre>
P DROP DESCRIPTION
Q 0141 INLET GUIDE VANE CONTROL TROUBLE TRIP</pre>
What is the cause of the trip?