Mark VI how to turn off sync

Dear all,

Recently we’ve been stuck in a 2nd breaker sync (I don’t want to discuss it in this thread).
As you know master reset l86mr is used many times without criteria (of course I totally disagree from it).
I saw using it and then machine fsr, tnr and of course tns drops (I believe it inhibits l69tmn .. l70rx4 and so speed reference goes down). I suppose this makes sense no?
can you confirm turn off sync (ca43sync off) is the proper way to do it? What should I expect ?

thanks
 
esganfia,

No; without being able to see the application code running in the Mark VI where you are working we can't confirm anything. And, as I say, if the Mark VI was configured and programmed by GE Belfort "engineering" then it would be extremely important to see the application code running in the Mark VI to say anything with any degree of certainty.

When trying to synch the second breaker (52L) is the Mark VI trying to adjust turbine speed (generator frequency)? Is the synch scope needle moving--is it moving fast or slow?

USUALLY, when there is a second breaker synch scheme there is another relay which switches the PT inputs to the Mark VI. Is that happening in this case?

Has this scheme ever worked in the past? Is this something new? Is it something which has changed recently for some reason?

Usually, a GE mark VI HMI synch display has some "indicating lights" on the left side of the display--a group of them which indicate whether certain permissives have been met. Are all of these lights green when trying to synch the second breaker?
 
esganfia,

No; without being able to see the application code running in the Mark VI where you are working we can't confirm anything. And, as I say, if the Mark VI was configured and programmed by GE Belfort "engineering" then it would be extremely important to see the application code running in the Mark VI to say anything with any degree of certainty.
How to do it? I’m not totally comfortable post the code. Pm you?
When trying to synch the second breaker (52L) is the Mark VI trying to adjust turbine speed (generator frequency)? Is the synch scope needle moving--is it moving fast or slow?
Yes and It’s moving fast
USUALLY, when there is a second breaker synch scheme there is another relay which switches the PT inputs to the Mark VI. Is that happening in this case?
Yes

Has this scheme ever worked in the past? Is this something new? Is it something which has changed recently for some reason?
Yes it worked several times during the last years and wasn’t modified

Usually, a GE mark VI HMI synch display has some "indicating lights" on the left side of the display--a group of them which indicate whether certain permissives have been met. Are all of these lights green when trying to synch the second breaker?
Correct. All conditions ok. I can say also L25P and L83AS were ok.
Answers in bold.
 
I don't do "off line"--the beauty of this particular forum is that MANY people can benefit from the questions asked by one person, now and later (because the site is easily searchable). So, no PM or DM. Nope.

If it's going too fast the Mark*'s 25A output will never close (too much slip).

Okay; that's good. Are the voltages "matched"? (Because it doesn't sound as if the speed matching is working very well....)

If it worked before, and under the same conditions (meaning no one's changed anything), then my guess is there's something else wrong with the 52L breaker close circuit--some permissive that isn't satisfied.

If it's not too crazy noisy in the room where the Mark VI is located (and you can shut off the A/Cs for a few minutes to help with that!), you can actually hear the synchronizing relays picking up and dropping out as the sync scope goes around and approaches 11 o'clock and passes 12 o'clock. It's faint, but you should be listening around the TTUR and TRPG and TREG cards (I don't have0 manuals to look at as I write this). Just have some give some kind of signal as the synch scope needle approaches 10 o'clock, and then as it passes 2 o'clock. You should hear some clicks as the electro-mechanical relays pick up and drop out. If you don't hear clicks, then something is amiss with the permissives for the Mark VI (I presume it synch's fine on 52G), but there's probably something additional for 52L that's not in the right state.

If you can hear the clicks, I would then suggest having a real serious look at every contact in the 52L breaker close circuit--including the position of any switches which have to be put in some kind of position by a human. Or, some output of a DCS or some relay panel that isn't in the right position or state. You should be able to use a voltmeter across various parts of the 52L breaker close circuit to see if the contacts in that section are closed or open.

It's more than likely NOT something wrong with the Mark*; it's more than likely something amiss with an input to the Mark* or something not right with the 52L breaker close circuit. Maybe the secondary disconnects of the 52L breaker aren't mating correctly? Or, again, something isn't in the proper position or state either because someone forgot the SOP (Standard Operating Procedure) or some part of the circuit was touched/modified (unintentionally) during maintenance on the 52L breaker, etc.

Please write back to let us know how you progress in resolving this problem. Because the real reason the threads on Control.com are so useful--now and in the future--is because, more so than many other similar sites, people provide feedback on the information or help they received here on Control.com, and let others know if the information was useful--or not, as the case may be--and how the issue was finally resolved. VERY valuable stuff. So, we look forward to hearing back from you!!!

Many times troubleshooting is a process of elimination--especially when the first couple of ideas turn out not to be the cause. Then, it's just a logical process of elimination.

Best of luck--and don't forget to write back...!
 
Dear all,

Recently we’ve been stuck in a 2nd breaker sync (I don’t want to discuss it in this thread).
As you know master reset l86mr is used many times without criteria (of course I totally disagree from it).
I saw using it and then machine fsr, tnr and of course tns drops (I believe it inhibits l69tmn .. l70rx4 and so speed reference goes down). I suppose this makes sense no?
can you confirm turn off sync (ca43sync off) is the proper way to do it? What should I expect ?

thanks

can you confirm turn off sync (ca43sync off) is the proper way to do it? What should I expect ?

in my world ca43sync_off is a cable remote setting.....!!!!!
 
A LOT of sites (try to) operate only using the DCS, whether that be via hardwired inputs/outputs and/or a combination of MODBUS or GSM AND hardwired I/O. A LOT of sites. They don't hardly ever look at the GE operator interface (HMI) and even less often look at the Alarm Window/Display(s). There are reasons for all of that--many of them caused by poor programming and configuration practices on the packagers' parts (all GE divisions are guilty of this, not just GE Belfort as I have occasionally pointed out), and poor maintenance (if you can even call it that).

THERE is usually, on the synchronizing display, a way of disabling AUTO SYNCH--by selecting SYNCH OFF.... But, again, that presumes people actually look at, and understand, the functions on the synch display (which most don't, and don't even try).

I still maintain, looking at the application code running in the Mark* is the best--nay, the ONLY--way to say with any degree of certainty how to disable AUTO synch'ing. In many cases, when REMOTE (or CABLE REMOTE, or SERIAL REMOTE) is selected, that automatically selects AUTO SYNCH, and sometimes ca43synch (_on or _off) works, or is not properly configured. MANY sites think that signals to the Mark* must be maintained--when, in fact, they are only supposed to be momentary. So, that little fact alone causes LOTS and LOTS and LOTS of problems.

Most sites have poor, if any, SOPs (Standard Operating Procedures). And, they are rarely followed, and even more rarely updated when situations or operations change. Every site that I have been to that was well operated used SOPs--EVERY ONE. This OJT (On-The-Job) training is for the birds, and the cows, and the pigs. It's mostly myths and wives tales and falsehoods--reinforced by the time-honored standard refrain, "Because we've always done it that way!" (If I had even a nickel (five measly US cents) for every time I've heard that uttered in a Control Room or PEECC or Control Cab, I would be a very wealthy man (because I believe in the power of compounding!).)

Anyway, the original poster is reluctant to share the app code--understandably so in todays world of cybersecurity (or lack thereof). So, we'll never know--and we shouldn't condemn or criticize or otherwise. From what I've read, the original poster seems to be doing his homework and reading the manuals and trying to ask questions to get to a resolution--but I do think he's overlooking the easy stuff (wiring; switches; permissives; etc.) and jumping to problems with the Mark*. We haven't asked the obvious question (because I've mostly given up asking): What Diagnostic Alarms are present? (Because NO ONE every looks at or tries to understand them; they're just nuisances, and beside, the GE guys all say the same thing: Diagnostic Alarms won't trip the turbine, so just forget about them," implying they are just nuisances (which they aren't).)

So, let's just wait to hear back and see how the troubleshooting is progressing. He has been able to tell us this second breaker synch scheme has worked in the past. It's just difficult to see how the app code in the Mark* or something in the Mark* hardware has failed--without a Diagnostic Alarm. But, again--we can't ask that.... So, we just do the best we can under the circumstances.

And be patient. You and I, Curious_One, have been doing this a LOT LONGER than the average bear.... Hey, hey, Boo Boo!!!
 
can you confirm turn off sync (ca43sync off) is the proper way to do it? What should I expect ?

in my world ca43sync_off is a cable remote setting.....!!!!!

Sorry L43SOFF_CPB (HMI) or R43SYNC_OFF (remote from DCS hardwire).
I'm trying to figure out to make the code "available".
 
esganfia,

What operating mode is selected on the Main (Start-up) display when 52L is being synchronized? Is it AUTO, or REMOTE (or some other name for "remote" control)?

Are you 100% certain that R43SYNC_OFF is driven by something from the DCS (either a discrete (contact) input, or a signal via MODBUS, or maybe GSM)? Because, GE has a habit of leaving the "cable remote" signals in the application code, and some plant designers choose not to use them. Meaning the code might be there, but there's nothing actually driving it.

It would seem to me that there must be some "selector" which tells the Mark VI to enable AUTO SYNCH--either a switch that an operator manually uses, or a target an operator clicks on a GE HMI display, or a target an operator clicks on on a DCS display. Then, from your description, it seems a different, unique set of parameters for synchronization are used--the +- 0.15 Hz.?.?.? And that makes the synch scope needle rotate very fast. I'm guessing that the higher frequency setpoint was something which was required by the grid to which you are synchronizing in order to ensure that positive MW flow out on to the grid when 52L closes--just a SWAG (Scientific Wild-Arsed Guess--but an educated SWAG, nonetheless). Because that's about the only reason I can think of for the "high" differential.

BUT, and I'm going to keep going back to this, WHAT HAS CHANGED? Because you have said it has worked in the past, this "scheme" with the +/- 0.15 differential, so, WHAT HAS CHANGED?

I think you're playing with fire if you want to change anything about the 52L synch scheme without first discussing it with the grid operators/regulators of the grid you are synchronizing to. They will certainly want to know of any changes you are making.

And, what happens if you make these changes (with or without consent/knowledge of the grid operators/regulators) and the breaker still doesn't close??? What are you going to do then? What if you gain their consent, and the breaker still doesn't close? How will that look?

Are you certain there isn't some permissive from the utility that has to be set to allow the unit to be synchronized to the grid??? Could that be what's "missing" here?

Seriously, go through the 52L breaker close circuit (using the schematic drawing), one permissive (contact) at a time, and make sure you understand where each contact (permissive) originates and that it is in the proper state (closed, probably...) when you are trying to synch to the grid.

If there are related Diagnostic Alarms on the Mark* when you are trying to synch, then I'm going to say the problem IS NOT the Mark VI, or any of the settings in the Mark VI. Again--you said this scheme has worked in the past. So, WHAT HAS CHANGED? Or, what is not in the right position or setting or isn't closing or whatever is causing the signal to energize the 52L breaker close coil and close 52L?
 
esganfia,

What operating mode is selected on the Main (Start-up) display when 52L is being synchronized? Is it AUTO, or REMOTE (or some other name for "remote" control)?
I'm sure it's AUTO.

Are you 100% certain that R43SYNC_OFF is driven by something from the DCS (either a discrete (contact) input, or a signal via MODBUS, or maybe GSM)? Because, GE has a habit of leaving the "cable remote" signals in the application code, and some plant designers choose not to use them. Meaning the code might be there, but there's nothing actually driving it.
Understood. R43SYNC_OFF is really driven by discrete contact input by DCS. DCS Commands are managed through OPC server which is communicating in GSM to HMI servers. L43SOFF_CPB and L43ASYNC_CPB commands are commonly used to turn off or getting in auto. In fact Hardwire signals are being "bypassed" by this kind of weird implementation.

It would seem to me that there must be some "selector" which tells the Mark VI to enable AUTO SYNCH--either a switch that an operator manually uses, or a target an operator clicks on a GE HMI display, or a target an operator clicks on on a DCS display. Then, from your description, it seems a different, unique set of parameters for synchronization are used--the +- 0.15 Hz.?.?.? And that makes the synch scope needle rotate very fast. I'm guessing that the higher frequency setpoint was something which was required by the grid to which you are synchronizing in order to ensure that positive MW flow out on to the grid when 52L closes--just a SWAG (Scientific Wild-Arsed Guess--but an educated SWAG, nonetheless). Because that's about the only reason I can think of for the "high" differential.
This block is managing the SYNC and SYNC permissive. Right know i can't i can get you the block detail, but it may be familiar for your. I think LK60TNMO is playing hard were.L60SYNC1.png

BUT, and I'm going to keep going back to this, WHAT HAS CHANGED? Because you have said it has worked in the past, this "scheme" with the +/- 0.15 differential, so, WHAT HAS CHANGED?
SWAG 1: I would say industrial network was dealing with just one out of two frame 6 unit (in the past the system inertia was much less and so we never got into the 50,1Hz)


I think you're playing with fire if you want to change anything about the 52L synch scheme without first discussing it with the grid operators/regulators if the grid you are synchronizing to. They will certainly want to know of any changes you are making.
No change on the synch scheme will be done.

And, what happens if you make these changes (with or without consent/knowledge of the grid operators/regulators) and the breaker still doesn't close??? What are you going to do then? What is you gain their consent, and the breaker still doesn't close? How will that look?
Believe me. I won't change the sync schematic. We are able to use (and we did)

Are you certain there isn't some permissive from the utility that has to be set to allow the unit to be synchronized to the grid??? Could that be what's "missing" here?
Yes I am sure. No other permissive here.

Seriously, go through the 52L breaker close circuit (using the schematic drawing), one permissive (contact) at a time, and make sure you understand where each contact (permissive) originates and that it is in the proper state (closed, probably...) when you are trying to synch to the grid.
SAMPLE.jpg
If there are related Diagnostic Alarms on the Mark* when you are trying to synch, then I'm going to say the problem IS NOT the Mark VI, or any of the settings in the Mark VI. Again--you said this scheme has worked in the past. So, WHAT HAS CHANGED? Or, what is not in the right position or setting or isn't closing or whatever is causing the signal to energize the 52L breaker close coil and close 52L?
I've tested K25P, K25A, K25, interface relay. OEM 25 is ok (it did allow us to sync manually bypassing all MVI circuit). I don't think it's a MVI problem. SWAG 2: I believe that day, the close windows was too short for MVI (-12/12 angle was approx. 200-600ms). Other days we had >>1s to close windows on OEM25 relay. That's why I was trying to figure out (in the other thread)VTUR working margins.
At bold
Thanks Again. I do appreciate your effort.
 
esganfia,

That circuit is heavily simplified, and in my personal opinion is dangerous if the actual 52L breaker close circuit is that and that alone. Further, the interposing relay introduces a possibly significant time delay which could--under the right conditions--cause the signal from the Mark VI to NOT be closed at the same time as the OEM 25 relay closure. Such as when the Mark VI is capable of greatly increasing the turbine-generator speed (frequency) because system inertia is low.

I also suspect there is some kind of "power management system" (sometimes called a "load sharing" system) which is being used to control the two GE-design Frame 6B heavy duty gas turbines when both are being operated at the same time, and which may also be affecting the speed control during synchronization (another educated SWAG on my part). If that "power management system" ("load sharing" system) is not prevented from sending signals to the Mark VI during synchronization attempts that could also be part of the issue.

Testing the synchronizing functions of the Mark VI is difficult and requires at least one variable frequency, variable voltage source, and another variable voltage source, and a frequency generator capable of driving all of the speed inputs of the Mark VI. These kind of testers are usually VERY expensive to purchase, and even to rent.

These kinds of issues start out as seemingly simple to resolve--as was said before. And, as was said before, if not solved early in the troubleshooting process they devolve into a process of elimination. Someone needs to delineate all of the possible issues, and then one by one, work through each one to prove it either is or is not the problem. As the issues are found to be working, the list of possibilities shrinks until the root cause is identified. Sometimes, as above, it can be a combination of two--or even more--things which, under the right conditions, cause the problem being experienced.

If you were able to manually close 52L while the turbine-generator was running, bypassing the Mark VI inputs, then it would seem the Mark VI signal is not occurring at the same time as the OEM 25 issue--and that interposing relay could be at least part of the problem.

The Mark VI has the Trend Recorder, which, unfortunately, can only capture data at no faster than 40 msec.... If you're 110% certain the OEM 25 is working correctly and will provide the level of protection you are comfortable with, you can use a manual switch (spring-loaded would be my personal requirement) to "simulate" the closure of the interposing relay when AUTO synch of 52L was selected. It's really no different than the MANual breaker close switch used for synchronizing (closing the 52L breaker) manually. If that works, then I would seriously be looking at the interposing relay to see if it isn't just old and tired and not responding as quickly as needed.

AND, I do think if the synch scope needle is moving faster than 4 or 5 or even 6 revolutions in a 10 second period then the turbine speed is really high--higher than it needs to be. Think about it--if the Mark VI is closing the auto synch contacts every time the breaker gets to approximately 11:30 o'clock and then opening the contacts when the synch scope rotates past 12:30 o'clock (both of those are guesstimates!!!) and that's happening 4 o4 5 or 6 or maybe even more times in a 10 second period, is that interposing relay going to be able to do the same thing with it's contacts? Will the contacts even close if the period the interposing relay coil is energized is milliseconds? Is that some kind of special interposing relay, or just an "everyday" electro-mechanical relay (or some kind of sold-state relay (I hope not, personally...)?

Anyway, it's a dilemma. I would be trying to find a way to either slow the unit down when synch'ing 52L, and/or testing that interposing relay to see if it's actually closing its contacts every time the synch scope needle passes through 12 o'clock. AND., if you're going to try changing the synchronizing speed, you should probably inform the grid regulators/operators what you're doing and why. It's very possible you can convince them the synchronization will be more reliable--which it's pretty certain they would like to see happen!

Hope this helps!
 
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