LM6000-PG Speed Switch Fail to Close
- Thread starter K5MOB
- Start date
This is what I see:
There are a number of faults that occur over a number of days but the day of interest appears to be January 29th.
It appears that the cause of the shutdown was due to the Generator safeset failure reported by the Sequencer code which occurred at 20:14:05.276 on Jan 29. The core logic reports that as a no motor condition. If you shutdown at a high temperature and you cannot motor to cool the engine down that triggers the 4 hour lockout which gets reported as an alarm. The speed switch failure to close occurs a minute and 8 seconds after the Generator safeset failure so I believe the switch failure is after the fact and is not what shut the engine down.
The IGV difference fault occurs about 5 seconds before the shutdown. An IGV difference fault is only an alarm and does not result in a shutdown. However, the difference fault may (or may not) be related to what was happening just prior to the safeset fault. Were the IGV feedback following the demand at the time of the event?
There is also a VSV LVDT A feedback fault reported by the core and a similar fault reported by the sequencer only 8 seconds after the safeset failure. The failure of one of the two VSV feedbacks should not result in a shutdown but like the IGV failure it may be related to how the engine was operating at that point in time. Was the VSV feedback following the demand at the time of the event? Also, faults related to the VSV and IGV can sometimes be caused by loose connectors so I would check those connectors at the earliest opportunity.
I am not familiar with some of the other faults but they do not appear to be faults that would result in a shutdown.
I believe that a safeset failure is an indication that the "safeset" that connects the generator shaft to power turbine shaft has failed. I would be very interested in what the engine was doing just before the shutdown particularly power turbine speed. Was the engine at high or low power? Was the engine accelerating at a high rate of speed? Was there noise on the speed sensor inputs?
Additional questions include:
What trouble shooting have you done?
What was the result of that trouble shooting?
Is the control a Mark VIe or a Woodward control?
Is the packager Baker Hughes or GE Vernova?
Regards,
shooter61
There are a number of faults that occur over a number of days but the day of interest appears to be January 29th.
It appears that the cause of the shutdown was due to the Generator safeset failure reported by the Sequencer code which occurred at 20:14:05.276 on Jan 29. The core logic reports that as a no motor condition. If you shutdown at a high temperature and you cannot motor to cool the engine down that triggers the 4 hour lockout which gets reported as an alarm. The speed switch failure to close occurs a minute and 8 seconds after the Generator safeset failure so I believe the switch failure is after the fact and is not what shut the engine down.
The IGV difference fault occurs about 5 seconds before the shutdown. An IGV difference fault is only an alarm and does not result in a shutdown. However, the difference fault may (or may not) be related to what was happening just prior to the safeset fault. Were the IGV feedback following the demand at the time of the event?
There is also a VSV LVDT A feedback fault reported by the core and a similar fault reported by the sequencer only 8 seconds after the safeset failure. The failure of one of the two VSV feedbacks should not result in a shutdown but like the IGV failure it may be related to how the engine was operating at that point in time. Was the VSV feedback following the demand at the time of the event? Also, faults related to the VSV and IGV can sometimes be caused by loose connectors so I would check those connectors at the earliest opportunity.
I am not familiar with some of the other faults but they do not appear to be faults that would result in a shutdown.
I believe that a safeset failure is an indication that the "safeset" that connects the generator shaft to power turbine shaft has failed. I would be very interested in what the engine was doing just before the shutdown particularly power turbine speed. Was the engine at high or low power? Was the engine accelerating at a high rate of speed? Was there noise on the speed sensor inputs?
Additional questions include:
What trouble shooting have you done?
What was the result of that trouble shooting?
Is the control a Mark VIe or a Woodward control?
Is the packager Baker Hughes or GE Vernova?
Regards,
shooter61
The VG issues is due to failed bushings in the IGV. The whole IGV will be replaced in the fall of 2024. The main issue we are attempting to address is the "Generator Safeset Failure" as that is what causing the unit to shut down.
We have basically tracked it down to the possibility of one of the NSD LP Rotor Sensors. We are waiting for the lock out to clear right now and will go into a crack to see if we find any difference in NSDA vs NSDB.
This failed on start up.. The first time we were at 5mw and it just shut down. The second time we just hit the wire and it shut down. The third time we set a trend up to monitor the items on the A_ESD page and went for a start, we did not even get to activate the sync before it shutdown and went directly to a 4hr lockout.
Sam
We have basically tracked it down to the possibility of one of the NSD LP Rotor Sensors. We are waiting for the lock out to clear right now and will go into a crack to see if we find any difference in NSDA vs NSDB.
This failed on start up.. The first time we were at 5mw and it just shut down. The second time we just hit the wire and it shut down. The third time we set a trend up to monitor the items on the A_ESD page and went for a start, we did not even get to activate the sync before it shutdown and went directly to a 4hr lockout.
Sam
The safe-set logic compares the NSD turbine speed sensor to the Generator Keyphaser speed sensor in the Bently vibration system. A difference greater than 150 RPM for 10 seconds triggers a No Motored shutdown independent of T48 temperature in this case, because potentially something is failed in the gearbox/coupling to the generator and cranking the engine could cause additional problems.
The Speed switch fault is if the Generator keyphasor signal is zero before the Zero speed switch is made within 60 seconds. This explains the time difference in the alarm log.
It could be that the keyphasor speed sensor has failed or there is a problem in the Bently on this signal or card. It could also be a real problem in the coupling/gearbox or the shear pin etc.
You can also download a high speed shutdown datalog if you do not have AppManager automatically collecting them (do a manual file retrieval with AppManager) and send it to the Woodward help desk ([email protected]) if you need to dig into it further.
The Speed switch fault is if the Generator keyphasor signal is zero before the Zero speed switch is made within 60 seconds. This explains the time difference in the alarm log.
It could be that the keyphasor speed sensor has failed or there is a problem in the Bently on this signal or card. It could also be a real problem in the coupling/gearbox or the shear pin etc.
You can also download a high speed shutdown datalog if you do not have AppManager automatically collecting them (do a manual file retrieval with AppManager) and send it to the Woodward help desk ([email protected]) if you need to dig into it further.
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