How do i troubleshoot synchronization failure? Our GE frame 9E gas turbine failed to synchronize, though the permissive is there but it can't synchronize. What should i do.
synchronization Failure
- Thread starter EBUWAODUWA
- Start date
Please i need the GE Mark VI Frame 9E gas turbine synchronization single line diagram.
A single line diagram for most every GE-design Frame 9E heavy duty gas turbine is specific to the site and the machine. You need to locate the Generator Control elementary (schematic) which shows the generator breaker closure circuit (and breaker open circuit) and PTs and CTs and synchronization circuitry. It will be found on site in the possession of the I&C (instrumentation & Control) department or the electrical department. There should be a copy of the Generator Control elementary in every control room, easily accessible to the operators, their supervisors and the I&C technicians, as well as plant management.
On the HMI Synch Display (presuming the turbine uses a GE Mark* HMI with CIMPLICITY or PROFICY MACHINE EDITION graphics package for graphical displays) you will find a vertical row of "lights." ALL of the "lights" must be green for synchronization to be successful. ALL OF THEM.
I presume you are referring to a Mark* Process Alarm which indicates FAILURE TO SYNCHRONIZE. In almost EVERY CASE this alarm is generated when automatic synchronization is enabled AND it takes longer than some preset amount of time for the generator breaker to close--usually 30 seconds or so. TYPICALLY, the FAILURE TO SYNCHRONIZE alarm DOES NOT abort the synchronization attempt sequence--it just warns the operator that it's taking longer than it should to close the breaker. Sometimes just waiting longer will eventually result in breaker closure--but some sites had their application code modified to abort the synch procedure when the unit failed to synchronize in the prescribed amount of time, and without being able to see the application code in the Mark * VI at your site we can't know if it's normal or not.
The typical causes of failure to synchronize are:
1) the grid frequency is unstable or erratic during synchronization;
2) the turbine-generator speed is unstable during synchronization;
3) there is some permissive in the generator breaker closure circuit which is not "made" (closed) which is preventing the breaker close signal from the Mark* VI from getting through the circuit to the generator breaker close coil;
4) one or more of the "lights" on the Synch Display are not green when the synchroscope needles approaches and passes through the 12 o'clock position;
5) the generator breaker is not properly "racked in" (in position) in it's normal position (there are primary (high voltage (, e.g. 11 kV) contacts, and low-voltage (usually 125 VDC) contacts for breaker status (open/closed; position; etc.) and closing and opening (tripping), closing mechanism charging voltage; etc.);
6) the exciter (AVR) is unable to "match" the generator voltage to the grid voltage, either because the grid voltage is too high or too low or it's unstable (this will usually result in one or more of the "lights" on the Synch Display not turning green during the synch process).
Some of the above conditions would result in Process Alarms and/or Diagnostic Alarms--but NOT all of them will. If it's reasonably quiet in the room where the Mark* VI is located it is possible to listen for relays picking up and dropping out on the TREG terminal board. As the synchroscope on the Synch Display approaches the 12 o'clock position you should hear three relays pick up followed by three more relays picking up and quickly dropping out as the needle passes the 12 o'clock position, followed by three relays dropping out. If you don't hear those relays picking up and dropping out, then it's most like some signal is preventing the Mark* VI from closing the generator breaker, OR the speed/frequency matching or voltage matching is not working properly.
You didn't say when this problem started--after a maintenance outage, after some work was done on the generator breaker assembly (breaker; mechanism; cubicle), or after a trip from load, or some work was done in the high voltage switchgear where one or more of the permissives for synchronization are located. You didn't say if the grid frequency or grid voltage was normal or not. You also didn't mention what alarms--Process AND Diagnostic--are annunciated and active (logic "1") when synchronization is in process.
If you want more help (we can't help you with the SLD (Single Line Diagram) because it's site-specific) we need more information. You have been given a good description of the FAILURE TO SYNCHRONIZE alarm and the typical causes of failure to close the generator breaker in a reasonable period of time. But, since we're NOT there alongside you and can't know what you know and can't see what you see you are going to have to provide more information. The better the information the more concise our response(s) can be. Just because you write to a World Wide Web forum with a poor description of some problem condition doesn't mean some expert can tell you with any degree of certainty what the problem IS and exactly how to fix. Synchronization is a very critical process and many aspects of it are specific to the site where the machine is located--regardless of whether it's a GE machine or a Nanjing machine or a Siemens machine. Without being able to remotely access your control system to observe what's happening--and still need some more information (the SLD, for example)--you are going to have to give us more information if you require more help. Start with telling us:
a) what alarms (Process & Diagnostic) are active before and during synchronization (attach a CLEAR photo of the Alarm Display to your reply)
b) when this problem started (after a trip from load; after a maintenance outage; after some work was performed on the generator breaker; etc.)
c) what the grid frequency is during synchronization (is it reasonable stable--or erratically changing?)
d) what the grid voltage is during synchronization (is it "normal" or higher or lower than normal when trying to synchronizee now)
e) what are the status of the Synch Display "lights"--you can take a photo of the display (make sure it's CLEAR when you send it!) so we know what each light is indicating); we need to know, specifically, what lights are green as the synch scope needle approaches the 12 o'clock position and if they are green as the needle passes through the 12 o'clock position
That would get us started--if you require more assistance.
OR, get a knowledgeable person to site to help with the problem(s).
By the way, if the above helps you to solve the problem without further assistance, please write back to let us know what you found and how you resolved the problem.
On the HMI Synch Display (presuming the turbine uses a GE Mark* HMI with CIMPLICITY or PROFICY MACHINE EDITION graphics package for graphical displays) you will find a vertical row of "lights." ALL of the "lights" must be green for synchronization to be successful. ALL OF THEM.
I presume you are referring to a Mark* Process Alarm which indicates FAILURE TO SYNCHRONIZE. In almost EVERY CASE this alarm is generated when automatic synchronization is enabled AND it takes longer than some preset amount of time for the generator breaker to close--usually 30 seconds or so. TYPICALLY, the FAILURE TO SYNCHRONIZE alarm DOES NOT abort the synchronization attempt sequence--it just warns the operator that it's taking longer than it should to close the breaker. Sometimes just waiting longer will eventually result in breaker closure--but some sites had their application code modified to abort the synch procedure when the unit failed to synchronize in the prescribed amount of time, and without being able to see the application code in the Mark * VI at your site we can't know if it's normal or not.
The typical causes of failure to synchronize are:
1) the grid frequency is unstable or erratic during synchronization;
2) the turbine-generator speed is unstable during synchronization;
3) there is some permissive in the generator breaker closure circuit which is not "made" (closed) which is preventing the breaker close signal from the Mark* VI from getting through the circuit to the generator breaker close coil;
4) one or more of the "lights" on the Synch Display are not green when the synchroscope needles approaches and passes through the 12 o'clock position;
5) the generator breaker is not properly "racked in" (in position) in it's normal position (there are primary (high voltage (, e.g. 11 kV) contacts, and low-voltage (usually 125 VDC) contacts for breaker status (open/closed; position; etc.) and closing and opening (tripping), closing mechanism charging voltage; etc.);
6) the exciter (AVR) is unable to "match" the generator voltage to the grid voltage, either because the grid voltage is too high or too low or it's unstable (this will usually result in one or more of the "lights" on the Synch Display not turning green during the synch process).
Some of the above conditions would result in Process Alarms and/or Diagnostic Alarms--but NOT all of them will. If it's reasonably quiet in the room where the Mark* VI is located it is possible to listen for relays picking up and dropping out on the TREG terminal board. As the synchroscope on the Synch Display approaches the 12 o'clock position you should hear three relays pick up followed by three more relays picking up and quickly dropping out as the needle passes the 12 o'clock position, followed by three relays dropping out. If you don't hear those relays picking up and dropping out, then it's most like some signal is preventing the Mark* VI from closing the generator breaker, OR the speed/frequency matching or voltage matching is not working properly.
You didn't say when this problem started--after a maintenance outage, after some work was done on the generator breaker assembly (breaker; mechanism; cubicle), or after a trip from load, or some work was done in the high voltage switchgear where one or more of the permissives for synchronization are located. You didn't say if the grid frequency or grid voltage was normal or not. You also didn't mention what alarms--Process AND Diagnostic--are annunciated and active (logic "1") when synchronization is in process.
If you want more help (we can't help you with the SLD (Single Line Diagram) because it's site-specific) we need more information. You have been given a good description of the FAILURE TO SYNCHRONIZE alarm and the typical causes of failure to close the generator breaker in a reasonable period of time. But, since we're NOT there alongside you and can't know what you know and can't see what you see you are going to have to provide more information. The better the information the more concise our response(s) can be. Just because you write to a World Wide Web forum with a poor description of some problem condition doesn't mean some expert can tell you with any degree of certainty what the problem IS and exactly how to fix. Synchronization is a very critical process and many aspects of it are specific to the site where the machine is located--regardless of whether it's a GE machine or a Nanjing machine or a Siemens machine. Without being able to remotely access your control system to observe what's happening--and still need some more information (the SLD, for example)--you are going to have to give us more information if you require more help. Start with telling us:
a) what alarms (Process & Diagnostic) are active before and during synchronization (attach a CLEAR photo of the Alarm Display to your reply)
b) when this problem started (after a trip from load; after a maintenance outage; after some work was performed on the generator breaker; etc.)
c) what the grid frequency is during synchronization (is it reasonable stable--or erratically changing?)
d) what the grid voltage is during synchronization (is it "normal" or higher or lower than normal when trying to synchronizee now)
e) what are the status of the Synch Display "lights"--you can take a photo of the display (make sure it's CLEAR when you send it!) so we know what each light is indicating); we need to know, specifically, what lights are green as the synch scope needle approaches the 12 o'clock position and if they are green as the needle passes through the 12 o'clock position
That would get us started--if you require more assistance.
OR, get a knowledgeable person to site to help with the problem(s).
By the way, if the above helps you to solve the problem without further assistance, please write back to let us know what you found and how you resolved the problem.
There's another couple of conditions that can sometimes prevent synchronization and the alarms associated with them don't indicate they will block synchronization. When the machine reaches FSNL (Full Speed-No Load; approximately 100% to 100.3% of rated speed) the Aux. L.O. Pump, the Aux. Hyd. Pump and the Emer. L.O. Pump (if my memory serves correctly) ALL have to be stopped. The two Aux. pumps should have stopped when the machine reached 95% of rated speed; the Emer. L.O. Pump should not have been running after a possible test during the initial steps of a START sequence and almost never during acceleration.
So, if either AUX. L.O. PUMP RUNNING or AUX. HYD. PUMP RUNNING process alarm is annunciated and active when the machine is at FSNL and the operator is trying to synchronize the unit, the typical application code will prevent synchronization until the pumps are stopped.
Why you ask do the Aux. pumps and the Emer. L.O. pumps have to be stopped to synchronize? Well, because the MAIN L.O. Pump and the MAIN Hyd. Pump are Accessory Gear-driven, and when the machine is at rated speed the Main pumps should be capable of providing the necessary oil flow/pressure to keep the machine running, and with the two Aux. pumps in standby they are available to keep the machine running in the event one or the other Main pump has a problem. And, the machine should never be running at rated speed with Emer. L.O. Pump running--because that's only for emergencies, such as when the Main AND the Aux L.O. Pump have failed or have serious issues. Should the Process Alarm text messages indicate the unit cannot be synchronized if the pump(s) is(are) running? Well, probably, but that will exceed the allowable number of characters in the alarm text message string (and wouldn't be displayed on the HMI or printed on the Alarm Logger (the unit IS using the Alarm Logger (the dot matrix printer) for printed copies of alarms, right????).
Anyway, if you would have provided the list of alarms and either of these alarms were active we could have immediately told you to resolve the reason for the Aux. Pump(s) or the Emer. L.O. Pump to be running when the machine was at rated speed and was trying to synchronize and failed.
I do note that your "original" post indicates "...the permissives is there..." but there are MANY permissives (the ones on the HMI Synch Display; the ones in the generator breaker close circuit; the Aux. Pump and Emer. L.O. Pump NOT running). And depending on the other Process and/or Diagnostic Alarms there can be other permissives which the Mark* VI is trying to alert a conscious operator to but are being overlooked because someone thinks it or the combination of them is irrelevant.
Give us the information requested and we can probably give you better guidance--if you haven't already realized the problem and resolved it. In which case it would be very helpful to many other people who read this thread, now and in the future, if you provided feedback about what the problem was and how it was solved.
And, that's another thing we recommend--using the Search feature at the top of every Control.com webpage. Because there's more than 20 years of Mark* and GE-design heavy duty gas turbine controls threads and information available in the Control.com archives by using the Search feature. AND, even this question has been asked and answered several times, though not exactly what you might think you were looking for. By reading several of the other past threads you would probably find most of the same information repeated in most of them. Use the Search feature of Control.com in you spare time (when you are tired of paging through and reading the Operation & Maintenance Manuals) and it's guaranteed you will learn a lot. A LOT more than reading the manuals.
Finally, you need to get and start reviewing and then reading GEH-6421, The Mark* VI System Guide, specifically Vol. II, to start understanding how each of the cards work and how to replace them and even get some Diagnostic Alarm troubleshooting help. There are some VERY good diagrams in that Volume (Vol. II), and you should refer to the section on the TREG card mentioned in a previous response to begin to understand how the synchronization function of the Mark* VI works. Really good stuff, and if you have questions we may be able to answer them. But you gotta give us good information in the beginning or we're going to be asking a LOT of questions. If you've tried some troubleshooting steps buy you haven't told us, it would be VERY HELPFUL if you told us WHAT you'd done, and even more importantly, what the results were (other than you believe it didn't solve the problem). Because sometimes what was done wasn't all that could have been done, and if we know what you've done and what the results were can be more helpful.
That's how this works. Here at Control.com.
So, if either AUX. L.O. PUMP RUNNING or AUX. HYD. PUMP RUNNING process alarm is annunciated and active when the machine is at FSNL and the operator is trying to synchronize the unit, the typical application code will prevent synchronization until the pumps are stopped.
Why you ask do the Aux. pumps and the Emer. L.O. pumps have to be stopped to synchronize? Well, because the MAIN L.O. Pump and the MAIN Hyd. Pump are Accessory Gear-driven, and when the machine is at rated speed the Main pumps should be capable of providing the necessary oil flow/pressure to keep the machine running, and with the two Aux. pumps in standby they are available to keep the machine running in the event one or the other Main pump has a problem. And, the machine should never be running at rated speed with Emer. L.O. Pump running--because that's only for emergencies, such as when the Main AND the Aux L.O. Pump have failed or have serious issues. Should the Process Alarm text messages indicate the unit cannot be synchronized if the pump(s) is(are) running? Well, probably, but that will exceed the allowable number of characters in the alarm text message string (and wouldn't be displayed on the HMI or printed on the Alarm Logger (the unit IS using the Alarm Logger (the dot matrix printer) for printed copies of alarms, right????).
Anyway, if you would have provided the list of alarms and either of these alarms were active we could have immediately told you to resolve the reason for the Aux. Pump(s) or the Emer. L.O. Pump to be running when the machine was at rated speed and was trying to synchronize and failed.
I do note that your "original" post indicates "...the permissives is there..." but there are MANY permissives (the ones on the HMI Synch Display; the ones in the generator breaker close circuit; the Aux. Pump and Emer. L.O. Pump NOT running). And depending on the other Process and/or Diagnostic Alarms there can be other permissives which the Mark* VI is trying to alert a conscious operator to but are being overlooked because someone thinks it or the combination of them is irrelevant.
Give us the information requested and we can probably give you better guidance--if you haven't already realized the problem and resolved it. In which case it would be very helpful to many other people who read this thread, now and in the future, if you provided feedback about what the problem was and how it was solved.
And, that's another thing we recommend--using the Search feature at the top of every Control.com webpage. Because there's more than 20 years of Mark* and GE-design heavy duty gas turbine controls threads and information available in the Control.com archives by using the Search feature. AND, even this question has been asked and answered several times, though not exactly what you might think you were looking for. By reading several of the other past threads you would probably find most of the same information repeated in most of them. Use the Search feature of Control.com in you spare time (when you are tired of paging through and reading the Operation & Maintenance Manuals) and it's guaranteed you will learn a lot. A LOT more than reading the manuals.
Finally, you need to get and start reviewing and then reading GEH-6421, The Mark* VI System Guide, specifically Vol. II, to start understanding how each of the cards work and how to replace them and even get some Diagnostic Alarm troubleshooting help. There are some VERY good diagrams in that Volume (Vol. II), and you should refer to the section on the TREG card mentioned in a previous response to begin to understand how the synchronization function of the Mark* VI works. Really good stuff, and if you have questions we may be able to answer them. But you gotta give us good information in the beginning or we're going to be asking a LOT of questions. If you've tried some troubleshooting steps buy you haven't told us, it would be VERY HELPFUL if you told us WHAT you'd done, and even more importantly, what the results were (other than you believe it didn't solve the problem). Because sometimes what was done wasn't all that could have been done, and if we know what you've done and what the results were can be more helpful.
That's how this works. Here at Control.com.
