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Synchronization Cards
Synchronization in MARK IV Gas Turbine

I want to know about synchronous cards in MARK IV. If just relay25 measure voltage and frequency and phase in Mark IV? Or there are individual synchronous cards for phase, frequency and voltage? We want to retrofit synchronous system of Mark IV with new synchronous Technology so it is very important to know all synchronous cards in MARK IV.

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>I want to know about synchronous cards in MARK IV. If just
>relay25 measure voltage and frequency and phase in Mark IV?
>Or there are individual synchronous cards for phase,
>frequency and voltage? We want to retrofit synchronous
>system of Mark IV with new synchronous Technology so it is
>very important to know all synchronous cards in MARK IV.

So, you want to replace one of the best features of the Mark IV--even though it is still better than some "modern" synchronization features available in 2019? The <SYNCH> module, mounted on the inside left wall of the Mark IV control panel enclosure was ahead of its time, and is still a very good and serviceable automatic synchronizer.

Using the Mark IV Speedtronic Elementary, Sheet 24H, I believe, shows the field connections to the <SYNCH> module: The generator (Incoming) PTs, the bus (Running) PTs, and the generator breaker close circuit. The signal outputs to <C> and <Q> software are shown on the same sheet.

That's really all there is to the Mark IV <SYNCH> module--it performs PT voltage input scaling, and has the contact output to close the generator breaker when AUTOmatic synchronization mode is selected rom the generator breaker panel Synch Selector Switch (43CS/SYNCH).

The synchronization check function is performed by an electromechanial relay in the generator control panel (25A and 25X). ALL the functions (synch check and auto synch) must agree to close the breaker in AUTO synch mode--this can be seen in the Generator Control Panel and Generator Breaker elementary (schematic) drawings. You may also find some relay outputs on the 49 sheets of the Mark IV Speedtronic elementary, driven by logic on the 22 sheets (probably beginning on Sh. 22B).

It's going to cost a pretty high amount of money to modify the synchronizing circuit and generator breaker closure circuits to accommodate a new synchronizing relay and associated devices (depending on the functionality you want). If the Mark IV autosynch function is working, why would you spend all that money to purchase, engineer and install a system to replace what is still--after it was designed more than 40 years ago--a very modern and working system (more sophisticated than some synchronization systems available on the market today in 2019!)--and still have a 40 year-old turbine control system which has some very serious shortcomings? (The Mark IV can trip the turbine and annunciate ZERO Process alarms to make the operator aware of why the turbine tripped. Without working LEDs in the Auxiliary Display it is difficult to impossible to determine why the turbine tripped under such circumstances. The operator interface (CRT and softswitches) are difficult to replace (though a couple of third-party vendors are doing so with mixed results). It's getting more and more difficult to find people who can work on the Mark IV when major problems arise.) It just doesn't make a lot of sense to replace a very technologically advanced feature (the <SYNCH> module) for its time and still today with a very expensive and so-called "modern" synchronization function in a 40 year-old (or maybe it's only 30 years old at your site) control system which has some serious issues even when it's working perfectly (the voting and I/O sharing schemes are less than adequate and GE recognized this when designing the Mark V to incorporate SIFT (Software-Implemented Fault Tolerance).

But, should you insist on this ill-advised endeavour you will need to learn how to use the Mark IV Speedtronic elementary (which shows Mark IV hardware AND software very clearly), the Generator Protection Panel elementary (schematic) and probably the Generator Breaker control circuit schematic drawings--all three--to discern all the things the Mark IV does to ensure a trouble-free and proper automatic synchroniztion. There were some early Mark IV control panels with didn't perform voltage matching--but that's a very simple thing if the operators are properly trained. Again, it's going to cost a lot of money--money which could be spent getting an entirely new and more modern turbine control system with better operator interface features (color, graphical operator interface; trending capabilities; etc.--which you may already have obtained from more than one vendor upgrading Mark IV operator interfaces). The cost of engineering the project, obtaining the equipment, installing and commissioning the equipment is going to be pretty high. Money more well spent upgrading the entire turbine control system to something more modern with a "newer" synchronization system, too.

Best of luck with your project.

Also, in the future, when asking for help it would be nice if the request was a question (such as, "Can anyone explain the Mark IV synchronization function and hardware, please?") instead of a demand ("I want to know ..."). I know some parts of the world don't even have a work for 'please' but demanding an answer is not very polite when asking for help with something. Just because the answers on control.com are free, we are still humans--people--providing them, and we appreciate being respected as human beings with feelings as well as technical knowledge.

1 out of 1 members thought this post was helpful...

Thanks a lot for answer.

Would you please advise us in more detail about retrofit of synchronizing system? We retrofit all hardware and software Mark IV system with SIEMENS PLC and PCS7 software. But just gas turbine and there is no retrofit for generator panel, so it is necessary to change synchronize system in turbine control panel side too. In page 24L, is there relay to set L25X2?

would you please tell us all relay such as relay 25 and phase check that related to synchronizing?

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ghaemi525,

You need to be referring to the schematic for the generator breaker close coil circuit. That schematic shows all of the "permissives" (requirements; contacts from various places--the generator control & protection panel AND the Mark IV) that are required to be able to close the generator breaker by energizing the breaker's close coil. I will attempt to draw a small portion of what the circuit may look like:


43S/MAN 43CS/CLOSE 25A*
- - - --------| |---------| |---------------| |------- - - - (continued
| | to the
| | generator breaker
| 43S/AUTO 25** | close coil)
--------| |------| |----------

*This comes from the synchronizing check relay (in the Mark IV era this was usually an electro-mechanical relay on the front door of the generator control & protection panel--a relay with a moving disk at many sites that drove a "telephone" relay with multiple contacts because of the current draw of the coil when being energized)
**This is "the" contact from the Mark IV automatic synchronizing module (<SYNCH>), Sheet 24H. You should find it at horizontal line 29 (each Mark IV elementary sheet is kind of a grid, with numbers on each vertical side of the sheet, and letters horizontally along the top of the page; the "contact" appears at grid coordinate 29G on the Mark IV elementary I am looking at, it should be near that on the sheet you are looking at). There is an asterisk to the right of "the" contact and below it there is a note saying "*NOTE: THE 25 RELAY HAS 6 CONTACTS IN SERIES." It's a physical (small) relay on the <SYNCH> module on the left side wall of the inside of the Mark IV. If GE supplied the generator control & protection panel, there should be a couple of wagon wheel-like symbols which indicates the wires attached to STB-1(5) and STB-1(4) go to the generator control & protection panel; if some other packager provided the Mark IV and the generator control & protection there may or may not be some kind of indication of where the wires go--and they may go directly to the generator breaker enclosure.

The 43S/MAN contact is closed when the unit is being manually synchronized and should be open at all other times. The 43S/AUTO contact is closed when the unit is being automatically synchronized and should be open at all other times. 43CS/CLOSE is the manually operated generator breaker close and open switch usually mounted on the front of the generator control & protection panel. It is closed when the synchroscope gets close to 12 o/clock and the operator moves the switch handle to close the contacts.

Synchronization usually requires two (2) contact closures to energize the generator breaker close coil. When manually synchronizing, the synchronizing check relay contact AND the 43CS/CLOSE contact (manually closed by the operator at the appropriate time) are required to be closed to energize the generator breaker close coil.

When automatically synchronizing, the 25 contact from the Mark IV AND the synchronizing check relay contact must be closed. (Selection of Manual or Automatic synchronizing mode is done with the 43S switch, usually also on the front of the generator control & protection panel.)

The use of a minimum of two contacts for generator breaker close coil energization is done to ensure that the breaker cannot be closed out of phase with the bus (running) grid voltage. AND, the synchronizing check relay (again--usually mounted on the front of the generator control & protection panel) is required for BOTH manual- and automatic synchronization. It is the one relay which is kind of the "final" check to make sure the generator breaker close coil can't be closed out of phase during synchronization (manual or automatic).

So, if you didn't make any upgrades to the generator control & protection panel the synchronizing check relay (and a possible auxiliary relay with multiple contacts in series (similar to the 25 relay on the Mark IV <SYNCH> module which has six contacts in series). You just need to replace the automatic synchronization function of the <SYNCH> module in the Mark IV.

Basler Electric and Woodward Governor Co. and I'm sure Siemens have automatic synchronization relays.

When synchronizing, it is important to (1) match voltage and (2) match frequency and (3) match phase angles. During manual synchronization, the operator does these three functions. During automatic synchronization, an automatic synchronizing "relay" (these days, just like in Mark IV days) is usually a digital (microprocessor-based) "relay" which adjusts generator terminal voltage to match bus (running) voltage, adjusts turbine speed to match bus (running) frequency and monitors the angles between phases to match phase angles and then issue a command to close the generator breaker by energizing the generator breaker close coil when generator voltage is nearly equal to bus (running) voltage and when generator frequency (turbine speed) is nearly equal to bus (running) voltage and the phase angles are withing an allowable amount (window) of each other. So, the automatic synchronizing "relay" has to have outputs to raise and lower generator terminal voltage, raise and lower turbine speed in addition to a "contact" to tell the generator breaker to close. And, as noted at the bottom of Sheet 24L, the sampling rate for phase differential monitoring is (1/divided by system frequency), so probably 1/50 seconds, or a 50 Hz rate (once every 0.02 seconds)--which is pretty fast for most PLCs.

Automatic synchronization is best left to purpose-built controllers (such as those from Basler Electric and Woodward Governor Co. and others) and purpose-built control systems (the Mark IV is a purpose-built control system--built to control turbines, and in this case a turbine-generator). Phase angle monitoring needs to be done at a very fast rate, and requires PT inputs from both the generator and bus.

Immediately below L25X2 (and L25X1) on Sheet 24L are sheet and/or grid coordinates. For L25X2 it shows 43K--meaning the software signal (the 'L' in front of the signal name means it's a software "relay" driving the contact) comes from line 43K on Sheet 24L. The "mapping" of the Mark IV elementary drawing is really very good. Whomever programmed the new PLC MUST HAVE learned how to follow the mapping and understand real, physical inputs and outputs as opposed to software "relays" ("coils") and contacts.

Hope this helps!!! You probably need to talk to a vendor that sells generator control & protection relays to get more help and suggestions for hardware for this function. But, the schematic of the circuit for the generator breaker close coil should tell you everything that is required for closing the generator breaker in both Manual and Automatic synchronization modes. Generally, for Mark IV applications the synchronizing check function is done by a physical relay somewhere outside the Mark IV control panel (in the generator control & protection panel), and the automatic synchronization function is done in the Mark IV. The 25 relay contact(s) of the Mark IV automatic synchronization function are wired to the generator breaker close coil circuit. As for what the automatic synchronization function has to do, hopefully the above is a good, basic description. For more, you will need to find an electrical engineer with experience in synchronization, and probably to get relay settings and perform relay testing. (Synchronization is NOTHING to mess around with!)

Finally, I have NEVER seen a turbine control system upgrade/replacement that performed the automatic synchronization function with a PLC. Most control system integrators/packagers will just buy a purpose-built relay to perform that function and wire it up to the PLC and exciter and generator breaker close circuit to do what is necessary. Again, it's nothing to mess around with--especially if you're unfamiliar with it or you've never done it before. PLCs can do a LOT of things, but automatic synchronization isn't one of them they do well.

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ghaemi525,

I don't know if I've answered "all" of your questions. The information shown on Sheets 24H through 24L primarily show software, which would be executed on the main microprocessor card of each of <R>, <S> and <T>--EXCEPT for the <SYNCH> module shown on the top of Sheet 24H, which is clearly labeled as HARDWARE in the upper left corner of the rectangle. This is basically showing the PT inputs to the Mark IV <SYNCH> module and the scaling of the two PT voltage signals transmitted to <R>, <S> <T> and <C> (as shown on the right side of the <SYNCH> module rectangle, and in the two SOFTWARE rectangles also shown on SH. 24H.

The signals inside the two SOFTWARE rectangles are then communicated to the locations shown after the arrows inside the rectangles (Sheets 22D, 24L and 24M on the elementary drawing I'm currently looking at as I write the responses to this thread).

So, there is only the one hardware module, <SYNCH>, that is dedicated to synchronization function, and the signals developed there are shared with <R>, <S>, <T> and <C>, and there are signals from Sheet 24H, horizontal line 76 (24H76), for the actuation of the 25 relay on the <SYNCH> module which come from <R>, <S> and <T> (as shown on the right side of the HARDWARE rectangle. And the one major digreesion from showing inputs to functions and hardware on the left and outputs from functions and hardware on the right, the <SYNCH> module 25 contact output to the generator breaker close circuit is shown at the bottom left of the HARDWARE rectangle.

<R>, <S> and <T> microprocessors execute the speed matching function, the voltage matching function (on the Mark IV elementary drawing I'm using), and monitoring of phase angle difference, as well as calculating the synchronizing permissive (L60SYN1 and L60SYN2) which basically look for minimum levels of PT voltage inputs from the generator- and bus (running) PTs.

So, really there's no other cards or relays, and when I refer to the "25 relay" I'm really referring to an electro-mechanical relay driven by L25 which closes multiple contacts (six contacts in series) when the generator breaker close coil is to be energized to close the generator breaker when all the permissives have been met AND automatic synchronization mode has been selected (voltage matching within allowable limits; speed (frequency) matching within allowable limits; and phase angle difference within allowable limits).

And, when all of that is "satisfied" the 25 relay contacts on the <SYNCH> module are closed (briefly) and the signal to close the generator breaker by energizing the generator breaker close coil is "sent" to the generator breaker close coil circuit.

That's it. Automatic synchronization again involves:

1) voltage matching (making sure the generator terminal voltage is nearly equal to or slightly greater than bus (running) voltage;
2) speed (frequency) matching (making sure the generator frequency (turbine speed) is nearly equal to or slightly greater than bus (running) frequency);
3) phase angle difference is within allowable limits.

To do these functions, the automatic synchronization function needs to know the generator voltage and turbine speed (which is directly proportional to generator frequency); bus (running) voltage and frequency; and to be able to raise and lower generator terminal voltage and turbine speed (generator frequency) as necessary to meet the required allowable limits, and then to issue a command to the generator breaker close coil circuit to close the generator breaker. Most of that is shown on Sheets 24H through 24L, with the "special" <SYNCH> hardware module and it's inputs and output shown at the top of Sheet 24H.

An automatic synchronization module from just about any manufacturer would do all of these things (adjust generator terminal voltage; match speed (frequency); and send a signal to close the generator breaker). Therefore an automatic synchronization module must be able to raise and lower generator terminal voltage, raise and lower turbine speed and determine phase angle difference to send the signal to close the generator breaker at the appropriate time. The synchronization permissives would typically be done by the PLC, and somehow communicated to the automatic synchronization module to perform the necessary functions when automatic synchronization is selected and permitted (permissives met).

That's about it! It's really pretty simple (the description). The actual "mechanics" of how all of that is done (in particular the high-speed calculation of phase angle difference) all depends on the automatic synchronization module designer/manufacturer. I've tried to basically describe how the Mark IV designers did it, and more detailed information is shown on the relevant 24 Sheets of the Mark IV elementary.

And, one last time, all of the "permissives" for energizing the generator breaker close coil to actually cause the generator breaker to close are shown on the drawing (schematic) of the generator breaker close coil circuit. In the Mark IV, some of the permissives are done by the Mark IV and "combined" in the permissives to the software functions to execute when automatic synchronization is selected and permitted.

Hope this helps! That's about all I can add to this discussion.