GE frame 9 Gas Turbine ' failure to synchronize'

GE Frame 9 gas turbine with mark iv control system is failure to synchronize and no other alarm in electrical side either in line circuit breaker or exciter & synchronizing panel. I am in bewildered condition.

Could anyone help me out what to be checked with explanantions?

anonymous

Not enough information. Manual synchronization or automatic synchronization?

Has anything been changed in the synchronization circuit--PTs (Potential Transformers), PT connections, PT fuses, etc.?

Has anything been done recently to the generator breaker close circuit?

Has the generator breaker recently been "racked out" (removed from it's cubicle) and then "racked in" again?

In other words, has something been worked on recently or been changed?

If the problem is with automatic synchronization, can the unit be synchronized manually?

If the problem is with manual synchronization, can the unit be synchronized automatically?

Have you verified that there is power in the generator breaker close circuit (in other words, are the fuses good)?

Have you looked at the generator breaker close electrical schematic drawing to see what permissives must be met for the generator breaker to be closed? Is there a tie-line breaker permissive, or a DCS permissive, or.?.?.?

Is there a synchroscope on the generator control panel? Was it working when trying to synchronize manually and/or automatically? Does it normally work when you are trying to synchronize automatically (sometimes they do; sometimes they don't--depends on the configuration)?

Many Mk IV turbine control panels were provided with AutoSynch modules (<SYNC>) mounted on the left side wall of the panel above the flame detector modules. Sometimes they were used when they were provided; sometimes they were not. Is there a sunch module in your Mk IV turbine control panel? Is it being used?

There's just not enough information in the original post to respond to. What have you done to try to troubleshoot the problem--other than look for alarms in exciter or synch panel? What synchronizing relays (25, 25X, and, if present, automatic synchronization relay, 25A) are being used in the circuit?

Providing as much information in the original post will allow a much better response in a much quicker time.

markvguy

Manual sysnchronization is successful but automatic synchronization not successful. Nothing done in PTs, PT connections, PT fuses. Nothing done recently to the generator circuit breaker. Synchronoscope is there and it is working as manual synchronization is successful.

One synchronziation interface module is there. And we replaced it but still automatic synchronization is not successful.

There is logic for L25, L25X1, L25X2. I am frankly speaking the logic is not clear to me. I read the literature for synchronization and some terms not clear, such as zero crossing voltage. One triangle also there in logic, I could not interpret it. Could you possibly explain, how the logic of synchronization work?

anonymous

anonymous,

How stable is the turbine speed at FSNL when you are trying to auto synchronize?

What does the display say when the unit is trying to auto synch?

So, while not answering the question directly, you seem to be saying that the Mk IV uses the <SYNCH> module to perform automatic synchronization, since you are describing the AUTO_SYNCH_INT_nnxx algorithm on Sh. 24L of the Mk IV Speedtronic elementary.

Basically, what the Mk IV does is compare the frequency of the running (line) voltage to the frequency of the generator voltage, and when the slip (the phase differential, usually measured in degrees or sometimes percent) is within the desired window, it energizes L25, which is the command to close the breaker. The triangle is a representation of the allowable limits of slip, and when SFDIFF1 and SSDIFF1 are within the limits, then L25X2 pickups, and when L25X1 is a logic "1" (which it should be when L83AS is a logic "1" and the generator phase is leading the running (line) phase), then L2 will pick up.

L83AS will usually be picked up when the turbine has determined that the generator frequency and the running (line) frequency are within limits and the Mk V is not trying to adjust turbine speed (generator frequency up or down, usually L60SYNL and L60SYNR are both logic "0")), someone has selected Auto synch (usually L52Z), there is bus voltage (usually L27BN), and there is no auto synch lockout (usually, L86S). Look at your elementary to see exactly what drive L83AS.

Have you verified that there is PT (Potential Transformer) voltage at the input to the <SYNCH> module (see Sh. 24H, STB-1(1) & -1(2), and STB-1(9) & -1(10))?

Have you verified that there is voltage at STB-1(5) and STB-1(4) (gen breaker close circuit voltage--usually 125 VDC) when the sync scope is passing through 12 o'clock? (Usually, the Mk IV synch contacts were in series with another synchronization relay, and the two have be closed at the same time to close the breaker. Verifying voltage at these points will confirm that there is no other permissive which is blocking auto synch.)

What are the values of DV and SVL when you are trying to synchronize? What is the value of SFL when you are trying to synchronize? What is the value of TNH when you are trying to synchronize?

When the Mk IV is trying to adjust generator frequency to get the proper phase and slip, it compares a value which comes from TNH to the value of running (line) frequency, SFL.

L60SYN1 and L60SYN2 are two signals which tell you whether or not the turbine speed (generator frequency) and running (line) frequency are within the limits defined by LK60SYN5 and LK60SYN6, respectively. They must both be a logic "1" for auto synchronization to occur.

So, there are some things to check. Remember: it is customary for the Mk IV breaker closure contact to be in series with another synch check relay's and they both have to close at the same time for the breaker to close. And be sure to verify that all the auto synch permissives in the generator breaker closure circuit are also met. While the <SYNCH> modules do fail (everything does sooner or later), this author has never replaced or heard of anyone replacing one--they are very reliable.

markvguy

Call Sesca Energy,
They have extensive knowledge of excitation / synchronization / protection....

Hi,

I work for Sesca and need some more information regarding GE.

tim. addison at sesca. com

GE is a major multi-national conglomerate.

You can find lots of information at http://www.ge.com.

But if you really want to know something specific about GE, then you need to tell us what your area of interest is and what your question(s) are.

Are you Zorro?

CTTech

I have been accused of being a swashbuckler, in my younger days.

But, that was a long, long, long time ago.

Nowadays, my pen is my sword (okay, it's become a keyboard).

Swoosh - swoosh - swoosh.

Is US = CSA?

CTTech,

Where are you headed with this line of questioning?

Zorro? US = CSA?

Come out and ask what you want to know, or say what you're trying to say. Most of us are adults here. And some of us are older than others (not that age necessarily equates with grown-up behaviour).

I apologize. Somehow, I must of posted an incomplete post.

I was inquiring about an observation I implied from one of your postings.

Specifically, "But if you really want to know something specific about GE, then you need to tell -->US<-- what your area of interest is and what your question(s) are."

OK Zorro, does CSA = US = GE?

From being a previous CSA customer that is almost a fruedian slip !! CSA is a Contractual Service Agreement my friend whereby the equipment supplier offers a customer a long term agreement covering servicing and parts for your machine.

CTTech,

I had MS-Excel generate three random numbers between 1 and 26, then converted those numbers to letters of the English alphabet to arrive at my posting psuedonym. Until rosest pointed it out, it had completely slipped my mind that CSA stood for Contractual Services Agreement!

I gained most of my experience working with GE as an employee, and a contractor, a Customer, and a competitor (I guess "competitor" doesn't really mean one can work with GE, but there are ways and it has been done, mostly out of expedience and necessity and sometimes with a blind eye).

"us" was used in the collective control.com meaning of the word. If a GE employee was posting here, I could imagine that would result in a torrent of requests and questions, and an awful lot of complaints. I think this site might be over-whelmed with people just trying to ask simple questions that GE doesn't have a method of answering, and certainly if they did some legal type would have to review each and every response and there would have be some kind of disclaimer at a minimum (as we all know, the US is a very litigious nation and GE is very image-conscious and would not want to be sued for something which might be taken or interpreted incorrectly).

And that's a real pity, because GE could really do themselves some good in the marketplace and the power generation community with such a site where people could ask basic questions, and even help each other. GE could really just ask as a moderator, keeping the threads on track, and providing clarification when necessary.

However, control.com is doing a nice job of filling the need. And, the community seems to be growing more aware of the presence of this site and of some of the good responses found here.

Swoosh-Swoosh-Swoosh!

(Perhaps I should change my pseudonym to Zorro. NAH!!!)

I anguished over even asking. But, I needed to know if the man behind the mask was GE. I, then, would be able to question you relentlessly about the difference between support and "we do not know" support.

Much of my anguish was related to the reason that control.com lost a great contributor (The legendary MarkVguy) was that the employer discovered the man behind the mask.

I would like to personally thank you for your past, present, and future contributions to speeddroop.com