I am needing a bit of assistance if at all possible regarding a MKV EX2000 Sync problem.

We had ran the unit earlier in the day and shut down with no issues noted or any Breaker prot. alarms. During our second start, we reached 3600 rpm with no issues and attempted to Auto Sync the unit. All of our permissive indications were green and our voltages, frequency, and speed were in just the same state as our other units that were synced just fine. During a closer inspection, at the PTBA board, I was able to monitor the latching relays as they cycled during sync. I did notice that as the relays cycled, they were not in time with the sync scope as shown on Cimplicity.

The Cimplicity breaker close timer indicator continues to count up but the breaker never actually attempts to close. During this time I have no alarms about the breaker or failure to close, etc. I do get a turbine sequence incomplete and a TCE breaker timer out of limits alarm.

I surely hope that someone has seen something similar to this. I have tried the old reboot of our HMI's, Breaker rack out, etc.....

The difficult thing about this, is that we can't test this without actually firing the unit and getting to 3600 rpm. If there is another way for us to thoroughly test out our circuit without firing that would be great too!

Thanks very much for any assistance!

B. Grave

 

Well upon further investigation, I found a possible issue with one of the interlock switches on our breaker.

I went ahead and also powered down the <P> x,y,z.

Can anyone explain the relevance of the 10 Green LED's on each of the MKV Speedtronic Boards?

Before rebooting the <P> I had one sequence of green led's and now I have a different sequence. At least now the sequence matches my other 3 units.

Thanks for any help you can offer!

Bob G.

 

Turbine Incomplete Sequence says it's taken longer to get synchronized to the grid than someone thinks it should have. And, TCE breaker close time out of limits says the feedback from the breaker hasn't changed state when it was expected to.

As you mentioned, on the Synch Display there should be a series of "lights" for the various permissives. They will be red when they are not met, and should turn green whey they are met. Conditions include speed matched, and voltage matched, and phasing within the window. If they're all green, then the Mark V and EX2000 are doing their job.

There may be some permissive in the generator breaker close string which is not met (closed) and the Mark V will keep trying to close the breaker, but if the signal can't get "past" that open contact/permissive, then it's not the Mark V's fault. Or, there may be a problem with some contact not making up properly (some secondary disconnect of the generator breaker is usually the culprit, and that's the reason most people rack the breaker in and out, but it doesn't always work).

You need to verify the voltages at each contact in the generator breaker close string. Not an easy thing to do, but, that's about the only way to check what's causing this problem--especially if the indicators on the Synch Display are all green, which would mean voltages are within tolerance and speed/frequency is within tolerance, etc. It's likely something outside the turbine control panel.

There is a way to check synchronization off-line, but it would require a variable frequency, variable voltage source (one at a minimum; two would be best), a variable frequency signal generator (for speed simulation), and a lot of jumpering and logic forcing. Not for the faint of heart.

If it's quiet enough in the room where the Mark V is located, you should be able to hear the relays cycle. It should something like this:

Click.....Click..Click...Click

There should be a slightly longer period between the first and second clicks, a short period between the second and third clicks, and a short period between the third and fourth clicks.

The first click is the Synch Check relays picking up and should occur as the synch scope needle is approaching the 11 o'clock position (approximately). The second click is the Auto Synch breaker close relay picking up and should occur just before the 12 o'clock position. The third click is the Auto Synch breaker close relay dropping out and should occur at or just very slight after the 12 o'clock position. And the fourth click is the Synch Check relay dropping out and should occur at about the 12:30 o'clock position.

Another possibility is that there is a mechanical synch check relay in series with the Mark V breaker close contacts that isn't closing as fast as the Mark V--which is another way of saying, there's another permissive/contact in the generator breaker closing circuit that isn't "making up" (closing). You might try manually slowing the turbine by clicking on SPD/LOAD LOWER.

So, check that generator breaker close circuit, each contact in the string.

Is there a SYNCH selector switch on the Generator Control/Protection Panel door? Is it in the right position?

Is the Master Control Selector is AUTO or REMOTE when this problem is occurring?

And write back to let us know what you find. "Feedback is the most important contribution!" (c) at control.com.

 

We have updated our Frame 7E speedtronic from M4 to M6e recently (first in US or we were testing site for GE for this upgrade). Again we digitalized all protections on our 13.8-230KV (we have GIS). During sych one of our GTG, we were not getting any signal (voltage) from GIS. further investigation led us to PT which was tripped or switched off?

But it is not your case as you mentioned that you can see both the voltages. I suspect as mentioned by CSA, your problem is outside the M5. Please check closing fuse on breaker or closing circuit breaker. Ours is DEC not GE. This happened to us once on our STG. I am sure you may also looked at breaker's hyd oil pressure, are there any alarm on the breaker which would otherwise won't allow breaker to close? There is a auto or manual sych procedures available from GE, for which you need not to go FSNL or you can simulate all conditions for breaker testing without even firing.

thanks

 

CSA,

All of our sync permissives were green, the sync switch was in the correct position in the ppeecc.

Our control was in the AUTO position, we don't use REMOTE.

I feel that our interlock switch was the culprit on our gen. breaker. I can't exactly confirm that until our next run attempt.

Back to the 10 leds on our Speedtronic boards.... Would there be any reason that my flashing sequence would change after powering down each part of the <P> core? I am glad that now all of our indications match with the other 3 units here. I would also like to know if I can use these LED's for troubleshooting in the future?

I am still surprised that the only alarm we got was a "breaker close time out of limits".

I appreciate the assistance. I am still on a learning curve having come from an LM6000 background - Woodward NetCon controls.....

Thanks again!

 

You're welcome for the information.

The LEDs do have a meaning, but the meanings changed when PROM revisions changed. And, to my knowledge, there is no 'secret decoder ring' for the LEDs, and if there were, it would be specific to the PROM revision in use on the card.

The LEDs do change sequence when there is a Diagnostic Alarm. And the fact that you did have a breaker close time out of limits Diag. Alarm would be one reason why they were out of sequence with the other panels at your site.

And, resetting the TCEA cards would likely reset the breaker close time out of limits Diag. Alarm, which would change the LED flashing sequence back to match the other panels (presuming they have no Diag. Alarms on the TCEA cards!).

As for your surprise about the lack of any other alarms related to the failure of the breaker to close, please propose some kind of indication that could be provided to the Mark V to point to a problem with synchronization. Other than monitoring each and every contact in the string there's not much else that could be done. And, if the problem (as I suspect) was related to the mechanical alignment of the secondary disconnects (which are used to connect your "interlock" switch to the gen breaker close circuit) then monitoring that would be difficult as well.

You just need to get familiar and comfortable with the drawings and configuration of the Frame units at the site. The Mark V basically told you that all of <b>its</b> permissives were fine, and yet, per the title of this thread you chose (as most do) to believe the problem was in either the Mark V or the EX2000. (Because there's "black magic" in them panels! Or at least that's what everyone believes, anyway.)

If all of the permissives are green on the Synch Display, and you have no alarms from the EX2000, then the problem is likely outside the panel. You need to become familiar and comfortable with locating the terminal boards where each contact is brought out to in order to be able to check each one to see if it's closed or not when a problem like this arises.

The site should have all the drawings you need; it's just likely they aren't all located in one place and people don't know where some are. Some are in the Service Manuals and Instruction Books; some aren't. Just look through every nook and cranny and cubbyhole, and get familiar with the layout of the units and where the TBs are to be better prepared for this in the future.

I seem to recall that if you are using the large "Magne-Blast" frame breakers with 125 VDC drill motors used to rack the breakers up and down that there was a TIL or something about a latch and pawl mechanism that would cause similar problems. You probably need to call GE or someone in your area that's very familiar with these breakers to get some help with that. Also, the alignment of the secondary disconnects (regardless of the breaker type/manufacture) can be an issue. If the breakers are racked in and out properly and fully, then the large mechanical forces at work when the breaker closes and opens can cause even more problems.

And, conductive grease, moderately applied, is also a good thing for these secondary disconnects. If the grease is old and or has attracted a lot of dust or dirt, it should be removed as best as possible and new grease moderately re-applied.

Hope this helps!

BTW, I'm not familiar with 10 LEDs an any card in the Mark V.... Not that it makes any difference how they're counted or where they're located; there is still no secret decoder ring to understanding their sequence. (Sorry!)