The unit is a Frame 5, Generator Alstom, System Mark VI, EX9100.
After a stop of 3 years, the turbine has been revised, generator changed.

Today we tried to synchronize without success:
* FSNL is reached

* P125GEN is connected on TTUR card terminal #3

* N125GEN is connected on TTUR card terminal #8

* we chose auto synch --> L25P and L83AS permissive switch to 1 --> all permissives seem ok --> but no change on K25P relay on TTUR card --> the contact between terminal #4 and #5 does not close

* the auto synch mode is trying to synchronize, the K25 relay on TTUR card is activated at each turn --> the contact between terminal #5 and #6 closes each synch try.

* the third relay K25A is not moving, neither the contact between #5 and (#6 or #7)

* we tried to change the relays without success

* we tried to change the TTUR card without success

* we tried to change the VTUR card without success.

I think the problem is on the K25P action not working (permissive).
Is there any permissive else than the L25P signal acting on the relay that is needed? Maybe on VPRO?

We disconnected the command to the 52G to measure a signal but we have nothing.

Thanks in advance for any help.
Regards
Vincent

 

vince64,

Thanks for the good information. I presume the Mark VI is a SIMPLEX, can you please confirm?

BOTH of the relays not energizing (K25P and K25) are required for automatic synchronization (presuming the TTUR wiring to the generator breaker close coil is correct). And, that's another thing: Is there +65 VDC at TTUR terminal 3? It should be possible to measure 125 VDC between terminals 3 and 8 when the turbine is at FSNL AND auto synch is enabled and active (because at that point, the only open contacts in the generator breaker close string should be on the TTUR).

What Process Alarms are active when trying to synchronize--please list ALL of the active Process Alarms present during synchronization (even if you don't think they're relevant to the problem being discussed--because Alarm Text messages can be VERY misleading!).

Is there a 125 VDC Battery Ground Alarm active on the Alarm Display of the HMI?

What are the logic states of L52Z and L52S during automatic synchronization? Sometimes these logic signals drive relays (directly or indirectly) which operate contacts in the breaker close circuit?

What is the logic state of L52GT when the unit is at FSNL? (Also, when the unit is on cooldown.) L52GT is usually a logic "1" below rated speed, and a logic "0" at rated speed.

Have you consulted the VTUR <b>&</b> VPRO sections of the Mark System Guide, GEH-6421? If so, which Revision of the manual are you using?

In Revision T, for example, the following note appears on the 'VTUR Turbine Speed Inputs and Generator Synchronizing on TTUR, SIMPLEX' figure:

"Note 3: Signal to K25A comes from TREG/IS215VPRO through TRPG & VTUR."

K25A is the synchronizing check relay--the "wide" window it's sometimes called--and it is driven by the VRPO cards in <P>, through the TRPG and VTUR (per the note above). Under normal condiions, it will close a split-second before K25, and open a split-second after K25.

K25 is the automatic synchronization relay--the "narrow" window it's sometimes called. It's driven by <R> (in a SIMPLEX configuration; <Q> in a TMR configuration) from the VTUR (which is located in <R> in a SIMPLEX panel, and in each of <R>, <S> and <T> in a TMR panel).

I believe all of the relays are 28 VDC relays (meaning their coils require 28 VDC to be energized). Since one of the relays (the K25A) relay is energizing at the appropriate time, it's presumed the 28 VDC the coils need is present. So, that's likely NOT the problem.

Some TTUR cards have hardware ("Berg") jumpers for K25P and K25 (JP1 and JP2, respectively), which must be in the proper position for SIMPLEX or TMR application. Does the panel use a TTURH1B card, and if so, are JP1 and JP2 both in the proper positions?

Since the K25 relay is working correctly, it's safe to presume the VPRO cards are all working correctly--but that's just a presumption. Are there any synchronizing-related Diagnostic Alarms being annunciated by any of the VPRO cards?

What Diagnostic Alarms are present on the VTUR card(s)? Since both of the relays that are NOT working are driven by the VTUR, it's safe to presume there is some Diagnostic Alarm on the VTUR card(s) which is indicating what the problem is--and which will be useful in troubleshooting the problem.

K25P must be closed under normal operating conditions during manual or automatic synchronization (it does not toggle/cycle like K25A and K25--it usually just energizes when L25P energizes and stays energized as long a AUTO synchronization is possible), and that is certainly a big problem if L25P is picked up (a logic "1") in the application code (using Toolbox) and K25P is not energized. I don't have access to any Mark VI application code at this writing, but I believe if all the permissive for Auto Synchronization are met and Auto Synch is selected (L83AS is a logic "1", which is usually the result of the output of a Command State Block driven by a "button" (target) on the HMI, then L25P will go to a logic "1"--which, if the TMR/SIMPLEX jumper on the TTUR card is in the proper position, should energize K25P.

Looking at the "generator" display with the Synch Scope and the AUTO/MAN/OFF synch selector "button" there should be a vertical line of green/red "lights" at the right side of the display, indicating that all of the synchronizing permissives are met--including speed within proper limits, voltage within proper limits, etc. If any of the "lights" are red, or switch to red just as the Synch Scope needle approaches 12 o'clock, then that's a problem for the K25A relay, and possibly for the K25P relay as well.

Generally, there's nothing "magic" about L25P driving K25P--but if there is there is usually at least one Diagnostic Alarm (on the VTUR card) to indicate a problem (unless the hardware ("Berg") jumper is not in the correct position).

The common thing to the two relays which aren't working is the VTUR. But, without being about to know all of the Process Alarms active during synchronization, and all of the VTUR Diagnostic Alarms (as viewed using Toolbox) it's difficult to say much more--than to inquire about positions of the hardware ("Berg") jumpers JP1 and JP2 on the TTURH1B card.

Also, are you sure the cable between the VTUR and the TTUR is properly inserted at both ends? It could be--though unlikely--there is a problem with the cable. It should be a straight-through cable (pin 1 at one end to pin 1 at the other end; pin 2 at one end to pin 2 at the other end; and so on, for all of the pins), and you could check to see if it's a cable problem (it's the one thing you haven't indicated was changed). It should be easy to check the cable to make sure that's not the problem using an ohmmeter/multi-function meter.

The "latches" on those Mark VI cables can sometimes be a real pain to get in the proper position to put the cables on so that all the pins are fully engaged, and then to latch properly. So, check the cables are fully inserted, they pins are fully visible in both ends of the cable connector (many times the pins have been damaged, sometimes since commissioning!), and that the latches are allowing full insertion--and are latched.

Hope this helps! Please write back with all of the requested information. And, to let us know how the troubleshooting progresses!

 

Dear Vince64,

Mr. CSA has done a good job of explaining the general operation of the sync circuit, and also asked for more information from you which will help us better understand your system. From your post I assume you are looking at the GEI and GEH manuals. I would like to clarify a bit that I read from your post that I do not agree with.

The basic system operation for the auto sync should work like this.

When auto sync is selected from the HMI, logic in the MKVI application code should energize K25P. This relay should be the first to close and should stay energized until the breaker closes.

K25A is driven by the VPRO and is responsible for the "Sync check". Depending on the settings in the VPRO it should close approximately 10 deg before and stay closed until 10 deg after top dead center of the sync scope assuming other permissives are met like generator and bus voltages. K25A should close and then open each time the sync scope approaches top dead center, or the zero crossing.

K25 relay is driven from the VTUR and is the last relay that should close in the sequence. It is responsible for closing the breaker at the zero crossing of the sync scope and adapts its closing command to account for the breaker time delay etc. No other relay s should interfere with the timing of the breaker close command.

As the manual suggests you need P125 attached to the TTUR card on terminal #3 and N125 attached to terminal #8.

Relay K26P is the sync permissive relay and closes the contacts across terminals #3 and #4.

K25A is responsible for the sync check from the VPRO, and closes contacts across terminals #5 and #6. To note terminals #6 and #7 are common on the TTUR board.

K25 is responsible for precise breaker closing command and is driven by firmware on the VTUR cards. It closes the contacts across terminals #4 and #5.

So during a normal auto sync sequence K25P should close with auto sync selected, the circuit should close across terminals #3 and #4 of the TTUR board. K25A should close with proper bus and generator voltages and when slip is with the + and - 10 deg window, this should complete the circuit between terminals #5 and #6. The final circuit between terminals #4 and #5 is controlled by relay K25 driven by the VTUR, and should close when the slip approaches the zero crossing of the sync scope.

"we chose auto synch --> L25P and L83AS permissive switch>to 1 --> all permissives seem ok --> but no change on K25P>relay on TTUR card --> the contact between terminal #4 and>#5 does not close" This is wrong, K25P closes across terminals #3 and #4, not #4 and #5.

"* the auto synch mode is trying to synchronize, the K25>relay on TTUR card is activated at each turn --> the contact>between terminal #5 and #6 closes each synch try." If contact is closing across terminals #5 and #6 as you say then this is K25A not K25.

"* the third relay K25A is not moving, neither the contact
between #5 and (#6 or #7)" You need to recheck your system. As stated above K25A closes across terminals #5 and #6.

Please clarify what exactly is happening again and write back so we can comment further. Please also provide information to answer questions raised by CSA.

 

Dear all

Thanks for replying. I was very busy with the unit and could not reply before.

As you detailed, the TTUR card has got 2 jumpers for Simplex or TMR systems. When I replaced the card, I forgot to put them on the Simplex position.

When I changed position, I forced L25P and it K25P has been energized properly. Then we directly tested normal synchronization.

As you say, K25P is the first to be energized when selecting auto-synchronize (permissive).
Then K25A in the synch. window and then K25.

Now synchronisation is working fine. Thanks for your help.
Regards

 

Thanks VERY much for the feedback! "Feedback is the most important contribution!"(c) here at control.com.

Please try to remember if you post again to tell us the Mark VI is a SIMPLEX; it can be very important to know for some troubleshooting.