You have to make sure that synchronizing permissifs are ok for a shot..like Voltage generator vs line matching, frequency line/generator matching...We have turbine driven(Fuel gas ) generator frame-V machine and GE- mark-5 control system, the issue is Generator is not synchronizing after FSNL, can anybody explain what are the check points need to carried out for trouble shooting from Mark-5 control system?
As far as I know, synch is the same on all MKV control systems.We have turbine driven(Fuel gas ) generator frame-V machine and GE- mark-5 control system, the issue is Generator is not synchronizing after FSNL, can anybody explain what are the check points need to carried out for trouble shooting from Mark-5 control system?
Thanks a lot CSA for the helpful answer. We had a similar case where the hydraulic pressure switch was giving wrong feedback; while everything in the circuit was ok. We stopped the turbine, replaced the switch, and then turbine started successfully and generator synced with the grid. I just want to ask what is the reason behind that? Why does the control system prevent you from sync in case aux. pumps are running? Is it to prevent extra load on the pump? or just to prevent the pumps from contiuously running during turbine operation?shimat2,
There should be a synchronizing display on the operator interface (you didn't say if you were using an <I> (running IDOS) or a GE Mark V HMI (running MS-Windows and CIMPLICITY). On the synch display there should be a few little squares in a vertical line (it's usually on the left side of the display). Those little square are either red or green--and for an Automatic Synchronization to occur, all of the squares have to be green.
A VERY common problem for a lot of sites is that one or more of the Auxiliary AC motors are running when the unit reaches FSNL (Full Speed-No Load; rated speed)--and they should have shut off automatically. This includes the Aux L.O. Pump motor (88QA-1) and the Aux Hyd Pump motor (88HQ-1). Both of these must be OFF (not running) before an auto synch can be performed. So, if you have alarms that either or both pumps are running while the unit is at FSNL, then you have to stop them.
The best way to stop them is to send a person to the MCC (Motor Control Center) where the motor starters for the motors are located. Let's say the Aux Hyd Pump motor is running. Find the motor starter for 88HQ-1, and there will be an H-O-A (Hand-Off-Auto) switch on the door of the starter. Also have someone standing by at the Accessory Gauge Panel (usually in the Accessory Compartment). Everyone should have radios (walkie-talkies) and the Control Room should be listening to the conversation between everyone. Have the person in the MCC move the H-O-A switch on the 88HQ-1 motor starter to the OFF position and hold it there for a few seconds. The person in the Accessory Compartment at the gauge panel should be watching the hydraulic system pressure gauge. It should remain at its normal pressure (usually around 1500 psig), but it should not drop very much. If it drops quickly and shows no sign of increasing, the person at the gauge panel should tell the person in the MCC to release the switch and it should automatically return to the AUTO position. This would indicate there is some problem with the Main (Accessory Gear-driven) Hyd Pump which needs to be resolved.
If the Hyd System pressure remains high and normal, the person at the gauge panel can tell the person at the MCC to release the switch and it should automatically return to the AUTO position and the motor should remain in the OFF condition. If the motor re-starts, then there is something amiss with the motor starter circuit, the pressure switch monitoring the Hydraulic System pressure, or there's something wrong with the check valves or the Aux. Hyd. Pump or the relief valve, etc.
The person in the Control Room should be watching alarms, and and pump motor or system-related alarms (L.O. or Hyd.) should be broadcast to everyone.
If the system pressure remains normal, and the aux pump remains OFF after this test, then it should be possible to automatically synchronize the generator.
Finally, the synch selector on the Synch Display should be in AUTO.... kind of goes without saying.
These are the most common problems with a synch system that was working but suddenly stopped. If these arent' the problems, AND if work was recently done on the generator breaker or something related to the PT (Potential Transformer) signals or the permissives in the generator breaker close circuit. At this point, you need to get someone knowledgeable to site, if someone can't say, "Oh, yeah--we worked on those circuits and we need to check to make sure the wiring was restored correctly," and find and resolve the problem.
Please write back to let us know what you find and how you resolve the problem.