Where the signal L4ex_strt_ss is produce In a Mark-v in a gas Turbine.
The signal is in the IO.ASG as EK2K do01 (l4ex_strt_ss) start request for ex-2000. It is an output from the mark-v to the ex-2000. In the dynamic rung display appear as a normally closed contact only. I can't find the genesis of the signal. Where and how it is produce? I have steam turbine mark-v control and in the dynamic rung display appears as a coil with his logic.

Thanks
Elvin

 

ELVIN APONTE,

This is what I have from a steam turbine Mark V CSP:<pre>
L4EXO L30EX_ L2EX_ L4EX_
FF_CMD L14HF TRIP ON_TD STRT_SS
------|/|-----| |-----|/|-------|/|--------------------( )</pre>
The Mark V communicates with the EX2K using STATUS_S protocol over the StageLink. The definition of the communications is made in IO.ASG. EX2K_DO01 is a bit in a communications scheme between the Mark V and the EX2K over the StageLink.

Remember: Dynamic Rung Display uses the CSP Segment Source files on the operator interface as the basis for animating the CSP. If the CSP Segment Source files on the operator interface don't match what's running in the Mark V, well, it's not going to display correctly. Contrary to popular belief, any animated display can ONLY use the CSP Segment Source files (Mark V Studio uses the .PRN file); no animated Mark V rung display can actually use what's running in the Mark V--there's no way to do that. The Mark V only has a compiled CSP file, which does not have any legible signal names or comments--the CSP compiler doesn't put them in the compiled file downloaded to the controllers. So, if you're using CSP Segment Source files which doesn't match what was last downloaded to the Mark V (and then the Mark V was rebooted to make the CSP run), then you're not going to see what's actually running in the Mark V.

Unfortunately, GE used _SS for both 'Single Shot' and 'Static Start', so I was a little confused by your question at first because, of course, steam turbines don't have static starters. (I confirmed this by looking at some F-class CSPs....) But, it seems in this case that L4EX_STRT_SS means 'Single Shot' even though it's not really a single shot in the strict sense of the term--at least not in the CSP I'm looking at. L2EX_ON_TD is a 0.5 second timer that picks up 0.5 second after the EX2K sends a feedback signal to the Mark V (over the StageLink) to tell the Mark V the EX2K is running.

Hope this helps!

 

These is the rung display we have in the steam turbine control.
The problem was that we are thinking that l4ex_strt_ss is the signal front the mark-v to the ex2000 in gas turbine that said the ex2000 start running.

We have 8 gas turbine and in all the signal only appear as a normally closed contact. In one of the unit the ex2000 is not running with the unit at 3600rpm. If the signal is forced to 1 the ex2000 begging to running.

But I did a test today in other 2 units that ex2000 start running automatically. The test was forced to zero L4EX_strt_ss from zero speed to 3600 rpm and see if the ex2000 running automatically. The result was that the ex2000 running and take care of the generator voltage without that signal. For me that signal is a manual start front mark-v gas turbine just in case ex2000 fail to running automatically . What do you think?

ELVIN APONTE,

 

ELVIN APONTE,

While the same exciter may be used for both gas- and steam turbines, when dealing with GE there are two different divisions which decide how to apply the exciter and how to control it--even using the same turbine control (Mark V). A former colleague at GE was fond of saying when it comes to turbine control at GE, "The standard is--there is no standard." And this seems to apply to your case where the same signal name is used for both gas- and steam turbine applications, but they seemingly don't "behave" similarly.

If I understand your statements correctly (and I'm not certain I do!), you said that L4_EX_STRT_SS is NOT written to anywhere in the GT CSP--that the only occurrence of L4_EX_STRT_SS in the GT CSP is as a NC contact in some rung (I'm not even sure which rung). If there's no coil for L4_EX_STRT_SS then L4_EX_STRT_SS will never change state. So, effectively it does nothing in the rung it appears in.

Now, on occasion Mark V logic signals which have no coil can get set to logic "1" somehow--don't know what the mechanism is that causes that to happen but when I've encountered it I have also been told that several MK5MAKEs had been done in very quick succession and several downloads and re-boots had also been done in very quick succession in a misguided attempt to solve some mysterious problem which only resulted in creating another problem.

Technically, it's very poor programming practice to leave contacts without coils in the CSP (with the same exception of LTRUE & LFALSE) but it does seem to happen occasionally, sometimes with bad results. And just running MK5MAKE and downloading and re-booting several times in quick succession is also poor practice, and not recommended (unless there is some odd desire to induce or create more unexpected problems--which should never be the case).

If I understood correctly that there is NO coil driving L4_EX_STRT_SS <b>AND</b> there is only this one NC (Normally Closed) occurrence of L4_EX_STRT_SS in the entire CSP, <b>AND</b> you find L4_EX_STRT_SS to be a logic "1" causing the NC L4_EX_STRT_SS to be open, then you can try forcing L4_EX_STRT_SS to a logic "0" and then <b>UN</b>forcing L4_EX_STRT_SS and observing if it remains at logic "0" or goes back to logic "1".

If it remains at logic "0" when unforced, then it was just "confused" and the mystery is (sort of) solved. (Don't force it to a logic "0" and then force it back to logic "1" and <b>THEN</b> unforce it. Force it to a logic "0" then <b>UN</b>force it--and watch it to see if it stays a logic "0" or reverts to logic "1.")

If, however, if you found it at logic "1" and forced it to logic "0" and then unforced it and it returned to logic "1" when unforced--then there <b>IS</b> a coil for L4_EX_STRT_SS somewhere in the CSP and there is something telling it to be a logic "1" in which case you have not found the rung with the coil for L4_EX_STRT_SS in the CSP.

Please write back to let us know how you fare--but, please be sure you understand what was written and ONLY force/unforced the signal when the unit is not running. Again, my original understanding was that the problem occurred with a steam turbine exciter.... that's why I found a steam turbine CSP and copied the rung from there. So, I'm not exactly sure I understand the issue correctly; sorry if I'm not (understanding the issue correctly).

But, if you found the NC L4_EX_STRT_SS at logic "1" with no coil driving it to be either a logic "1" or a logic "0", and there truly is no other occurrence of L4_EX_STRT_SS anywhere else in the CSP, and you forced it to a logic "0" and it had no effect on the operation--meaning the exciter started and ran properly--then I would say that in that Mark V L4_EX_STRT_SS somehow got "confused" and we are all <b>EXTREMELY INTERESTED </b> to know what happened to L4__EX_STRT_SS when you unforced it. Did it stay at logic "0" --or did it revert back to logic "1"?

And, I would also suggest that the NC L4_EX_STRT_SS be removed from the rung of all similar turbines, gas or steam--but <b>NOT</b> both gas- and steam turbines. Only the turbines where there is no coil driving L4_EX_STRT_SS <b>AND</b> there are no other occurrences of L4_EX_STRT_SS in the CSP. This to prevent possible similar occurrences of the same problem from happening in the future.

Looking forward to hearing back from you with the results of UNforcing the signal and what happened!

 

Thanks:

The normal state for L4EX_STRT_SS is zero. The problem was in a Gas Turbine. When forced to one and unforced it keeps in one. Then forced to zero and unforced and it keeps in zero.

The rung is in SEQ_LOAD # 43. Is a n/c contact to drive a signal through a TMV L41FY. But L41FY(Generator field flashing time delay) not assigned in the IO.ASG file neither SITE.ASG neither Factory.ASG.

Thanks for your attention.

Elvin Aponte

 

ELVIN APONTE,

Thanks for the feedback!

Signals don't have to be in a .ASG file to be used in the CSP. Many signals are in the UNITDATA.TPL file as they are commonly used in many applications. You should only find I/O-related signals--and, of course, EX2000-related signals (just to be consistently inconsistent)--in IO.ASG.

And, FACTORY.ASG is where the factory can add non-I/O-related signals that don't appear in a .TPL file. And, SITE.ASG is where field personnel can add signals that don't appear in FACTORY.ASG or a .TPL file. (Not every signal in a .ASG file is used in every CSP or has to be used in a CSP. And, not every signal in a .TPL file has to be used in a CSP.)

So, in effect you've proven there is no coil writing to L4_EX_STRT_SS in the CSP. And, since nothing is driving it you can do one of two things: remove the NC contact from the L41FY rung, or write a rung using a NO LFALSE to drive L4_EX_STRT_SS to make sure it always stays a logic "0" and leave the NC L4_EX_STRT_SS in the L41FY rung.

Under normal conditions, it should be okay but as you experienced, sometimes bits go astray with nothing driving them to be "0" or "1". And, it is just poor programming practice to leave such logic signals (without coils) in the CSP, which can lead to this kind of problem.

Anyway, it seems the mystery is solved.