Gas Turbine control - Hardware Part Trip of L4

N

Thread Starter

Neo

CSA:

Sorry for be absent for about two weeks.

<i>"So, let's get after finishing our L4 journey. We have other things to discuss (TREG and TRPG, specifically)."</i>

CSA, where should i start? I need your guidance.

I think there are software trip part and hardware trip part. All we discussed before are about protection trip in <Q> core, that is software trip, and the protection trip in VPRO card is the hardware trip. And VPRO works with VTUR.

TRPG is the terminal board of VPRO and TREG is the terminal board of VTUR, and TREG provides the positive side of the dc power to the solenoids, and TRPG provides the negative side.

That is all i know about hardware part trip of L4.

Best regards!
Neo
 
neo,

Welcome back; I've been a little busy, also, so it hasn't been a problem.

So, I'm taking it that you're satisfied with the L4 rung (<Q> application code) discussion(s)?

I'm really curious, though, to finish the starting means thing. Your started that thread saying you'd been asked to look at the application code, and it seemed to be because of an issue. If you've asked GE for their input on the matter, it would be really helpful if you could share that with us. If there's something to be learned--I'm always looking to add to my memory banks. If there's a problem, then it's safe to say there may be other plants with a similar problem. So, can we finish that before we go too much into this thread?

Also, I would like to you to look over your Mark VI System Guide, GEH-6421, and be sure your association of the TREG with the VTUR, and the TRPG with the VPRO, are correct.

I will say that the VTUR and the VPROs (in a TMR panel) work together to power the fuel stop valve(s). But, I think we need to double-check what works with what.

The associations are shown in both the VTUR and VPRO sections of the manual--almost the same drawings in each. So, that should help.

And, please, let's finish the starting means thread.
 
CSA:

> <i>So, I'm taking it that you're satisfied with the L4 rung (<Q> application code) discussion(s)?</i>

CSA, i think i should not be satisfied with it if i wanna to be a knowledgeable man like you. But i don't know how to continue. So i think maybe it would be better to cover hardware part of L4 first.

> <i>I'm really curious, though, to finish the starting means thing. Your started that thread saying you'd been asked to look at the application code, and it seemed to be because of an issue. If you've asked GE for their input on the matter, it would be really helpful if you could share that with us. If there's something to be learned--I'm always looking to add to my memory banks. If there's a problem, then it's safe to say there may be other plants with a similar problem. So, can we finish that before we go too much into this thread?</i>

CSA, i would like to ask, but it is beyond my responsibility. anyway, we don't have that problem that is caused by L14HT thing. I will keep this problem in mind. if i have that answer, i will respond at first time.

BTW, i find L14HT is also used in gas fuel leakage test.

> <i>Also, I would like to you to look over your Mark VI System Guide, GEH-6421, and be sure your association of the TREG with the VTUR, and the TRPG with the VPRO, are correct.</i>

I checked that and find TREG is the terminal board of VPRO, while TRPG is the terminal board of VTUR.

CSA, how to get a better understanding of hardware part of L4, please.

Best regards!
Neo
 
Okay, Neo,

It's important to note that the fuel stop solenoids of GE-design heavy duty gas turbines with Mark VI turbine control systems are connected "between" the TRPG and TREG cards. That is, one side of the fuel stop solenoid is connected to a TRPG card, and the other side of the solenoid is connected to the TREG card.

The fuel stop logic signals (like L20FG1X and L20FL1X, for example) control the Primary Trip Relays (PTRs) which are on the TRPG--so the trips from application code in the Mark VI are what controls the Primary Trip Relays. Looking at the two logic signals, one can see how L4 will allow energization of the solenoids, and how the "loss" of L4 (when a trip or shutdown--remember, L4T or L94T) de-energizes the fuel stop solenoid logic signals and drops out the associated PTRs. And when energized the PTRs supply the negative side of the 125 VDC to the fuel trip solenoids. (The fuel trip solenoids of GE-design heavy duty gas turbines must be ENERGIZED to allow fuel to get to the turbine, and when they are de-energized they stop or prevent the flow of fuel to the turbine.)

L4_XTP (the Master Protective Cross-trip) controls the Emergency Protective relays--along with:

1) the seven (7) possible discrete trip inputs to the TRPG;

2) the E-Stop pushbutton inputs to the TRPG;

and,

3) the Emergency Electrical Overspeed trips in the <P> core.

The Emergency Trip Relays (ETRs) control the positive side of the 125 VDC that is applied to the fuel stop solenoids. When energized the ETRs supply the positive side of the voltage to the coil. (Again, the fuel stop solenoids of GE-design heavy duty gas turbines must be ENERGIZED to allow fuel to get to the turbine, and when they are de-energized they stop or prevent the flow of fuel to the turbine.)

When both the negative and positive sides of the 125 VDC is applied to the two leads of a fuel stop solenoid it will be energized. The loss of either the negative or the positive sides of the 125 VDC voltage to a fuel stop solenoid is lost (when either the PTRs <b>OR</b> the ETRs are de-energized) the fuel stop solenoid will no longer be energized and the fuel flow to the turbine will be stopped.

L4 is the inverse of L4_XTP which means that in order to get the ETRs to pick up it means that:

1) all of the used discrete inputs must be CLOSED;

2) the E-Stop Push-buttons connected to the TRPG must all be CLOSED;

3) the Emergency Overspeed Trip detection must be unlatched

and,

when L4_XTP goes to a logic "0" (when L4 goes to a logic "1") the ETRs will be energized and the positive side of the 125 VDC will be applied to the fuel stop solenoid valves.

The PTR contacts and the ETR contacts are arranged in a two-out-of-three fashion, like so:<pre>
<R> <S> L20FG1X <X> <Y>
-125 VDC -------| |----| |----------/\ /--------| |----| |------- +125VDC
| <S> <T> | \/ | <Y> <Z> |
---| |----| |---- ---| |----| |----
| <R> <T> | | <X> <T> |
|--| |----| |---- ---| |----| |----</pre>
While it's not likely that a single control processor or a single protective processor will try to trip the turbine, it is possible and does very rarely occur (and is accompanied by Diagnostic Alarms, and in some cases, a Process Alarm or two). But, this is all done in "hardware" using traces on the TRPG and TREG cards and contacts of the PTR and ETR relays. So, this is how a software-generated/detected trip will eventually cause a turbine trip (by removing either or both of the 125 VDC sides of the power supply to the fuel stop solenoid). Again, the PTRs are on the TRPG and the ETRs are on the TREG. It's this combination of software and hardware that makes the Speedtronic so reliable (because this is used in one way or another in all the digital Speedtronic turbine control systems, from Mark IV through the Mark VIe).

It's also important to note that the emergency overspeed protection in the <P> core (performed by each of the VPROs) is also a speed rate-of-change protection. So, if the speed increases really fast, or if it decreases really fast, then the overspeed detection will be actuated and the ETR for that VPRO will trip. I said "... the ETR for that VPRO will trip...." because there are three independent speed pickups, one to each of the VPROs, so that if one speed pickup fails when the turbine is running then the VPRO that speed pickup is connected to will de-energize it's ETR relay. Speed pick-ups don't usually all fail at the same time, but when they do fail they usually fail intermittently at first, which can drive the VPRO it's connected to crazy--generating a lot of nuisance alarms (Process- and Diagnostic). But, that's better than tripping the turbine, and it is an indication that the speed pickup is failing or has failed. And, at least one of the Process Alarms that will be annunciated will be an "overspeed" alarm--because either the speed feedback is intermittently changing very quickly, or it has dropped precipitously to zero, and either of those conditions will actuate the overspeed detection logic because of a sudden change in the rate of speed increase and/or decrease.

Next reply will cover how the E-Stop P/Bs "control" the ETRs. But, if you want to anticipate the discussion, have a look at the drawings in the System Guide manual.

Finally, I'm no "wizard" or super-intelligent person. I had the good fortune to spend a lot of years waiting for construction personnel to finish installing turbines (including the wiring and field devices) and used that time to study the drawings and manuals. I was also fortunate enough to have had the ability to contact knowledgeable individuals who could "fill in the gaps" for me early in my career, and used that to form my "thinking" and deduction skills. There's still a <b>LOT</b> I have to learn, and a <b>LOT</b> I haven't seen, but using the philosophies I've come to learn and understand it's usually not too difficult to understand why or how some things are done the way they are even if they seem to be very convoluted. As we've learned, some things are actually very simple though they appear to be very complicated.

There are MANY ways to enhance and improve the reliability and availability of control systems--not just this way. But, I've come to know that the methods employed by GE (even though they are NOT well-documented, if they are documented at all) are among the simplest and most robust in the power generation industry--again, even if at first glance they seem very complicated. It just takes a willingness (and the time!) to dig into the available documentation and manuals and follow signals through the circuits and logic. That's one of the really good things about GE Speedtronic turbine control systems--they are usually much better documented than most other comparable systems. By that I mean that there most of the algorithms and "blocks" used have very simple diagrams which can be used to understand the flow of signals through them. Most of the other control systems I encounter just use empty rectangles with some inputs and outputs (and the inputs and outputs can be on either side, top or bottom of the empty rectangle) to represent functions or algorithms. One has to find a manual to understand what happens inside the empty rectangle, and that's not always easy to do because many of the descriptions don't include and "logic" diagrams, just words.

I appreciate your kind words, but, they are unwarranted except to the extent that I spent a good many nights and weekends in hotel rooms all around the world studying and marking-up drawings and redrawing diagrams (all unpaid) in order to improve my understanding. Because of the kind and helpful people I encountered early in my career as a Field Engineer I try to help as many people as I can to help develop and improve their understanding--because had I not had the extremely good fortune to have worked with those people I would have left this field very quickly, because of the poor training I received early on and the dearth of documentation available. So, really I'm just repaying a debt of gratitude for the knowledge and guidance I received early on. So, now more thanks are required. I do appreciate positive--as well as negative feedback (when accompanied by an explanation of what could have been done better!)--but let's just keep the kind words to feedback, positive and/or negative.

Also, if you have other questions or functions you want to understand please open a thread and we can try to help explain them.
 
CSA:

I read and reread your response,and it really helps! And thanks for your drawings.

Following your guidance, i refer to TREG terminal board drawings in the System Guide Manual.

According to your reply there are four conditions that the fuel solenoid will loss power:

1) Protection algorithm in <Q> core;

2) Over speed protection in <P> core;

3) 7 trip interlock digital inputs; //i think this 7 digital inputs finally goes to <Q> core through VPRO, and when anyone is logic 0, the turbine trips.

4) E-stop
I don't understand why there has to be three ETR relays to form one group for one VPRO (R,S,or T).

Next reply will cover how the E-Stop P/Bs "control" the ETRs. But, if you want to anticipate the discussion, have a look at the drawings in the System Guide manual.

CSA, i am learning to read hardware drawings. I think if E-stop PB is pushed down, then the power of ETR will lost. thus fuel solenoid is cut off electricity, and the GT trips.

I am not sure whether it is right but i tired!

CSA, i think i am fortune to find this forum, and encounter you, and your reply helps me a lot. Without your help, i am not sure where i am. The GT control seems so difficult to learn for me at very beginning.

I think there is a long way to go, but i am willing to continue.
Thanks a lot!

Best regards!
Neo
 
Neo,

I'll try to answer your questions, but I'm not clear on at least one of them.

Yes; you are basically correct that there are four basic ways to trip the turbine <b><i>via the Speedtronic turbine control system:</b></i>

1) Application code (high-high vibration; loss of flame; exhaust overtemperature; primary electrical overspeed; etc.)

2) Emergency electrical overspeed (<P> core--which is actually three independent, but associated--processors, performing a two-out-of-three vote on overspeed), including the (non-adjustable) speed rate-of-change detection/trip

3) Seven (7) discrete trip inputs to TRPG which open to trip; remember these cannot be inverted, and they cannot be forced in Toolbox/ToolboxST.

4) E-stop P/Bs

> I don't understand why there has to be three ETR relays to form one group for one VPRO (R,S,or T).

There are only three VPROs, BUT there are multiple ETR relays for each of <X>, <Y> and <Z> which are independent of, but associated with <R>, <S> and <T>). If you notice on the drawings in the System Guide, there are three PTRs for each of the solenoid outputs (20FG-1; 20FL-1) and each group of three is driven by a unique logic signal (L20FG1X; L20FL12X, respectively). However, for the ETRs, there is really only one logic signal: L4_XTP, but there needs to be multiple outputs (one for each fuel trip solenoid circuit). So, that's whey there are multiple ETRs for each of <X>, <Y> and <Z>. They will all be energized when the second, third and fourth conditions are all satisfied--and they will all de-energize when any one of the second, third or fourth conditions are not satisfied. So, it's not necessary to have multiple logic signals to drive the ETRs; a single one will do--L4_XTP. And this basically says the ETRs can't be energized unless L4 is energized.

Without being able to post a drawing from the System Guide this is going to be rather difficult, and, because there are SO many revisions of GEH-6421 out there I don't know which revision you're looking at so I can't tell you to look at a specific page or drawing, but here goes anyway.

Go find the TREG card section in Vol. II of GEH-6421, and find a drawing which shows the 'Trip Interlocks, and Trip Solenoids.' At the lower right corner of the card are the seven discrete trip inputs (called "interlocks") and the E-Stop P/B inputs. Let's start with the E-Stop P/Bs. When all of the E-Stop P/Bs are closed the circuit is made up (and if all of the available inputs to the board aren't used by individual E-Stop P/Bs or strings of E-Stop P/Bs then jumpers must be used to "simulate" closed inputs) then the three relays K4X, K4Y and K4Z are energized. Note that the voltage source, P28VV passes through the E-Stop P/Bs and through the coils--so that any open E-Stop P/B circuit interrupts the flow of 28 VDC to the K4X, K4Y and K4Z coils.

Directly above the E-Stop P/Bs are the three groups of ETR relays (KX1, KX2, KX3; KY1, KY2, KY3; KZ1, KZ2, KZ3). Those ETR relay coils are 28VDC coils, and K4X, K4Y and K4Z allow 28 VDC to get to one side of each group of those ETR coils. The rectangle on the other side of the ETR relay coils with "RD" inside the rectangle, is the Relay Driver. GE primarily "sinks" DC relay coils to ground to "energize" them--meaning that the Relay Driver, when actuated by the logic driving it, connects the coil to ground and since the other side of the coil has 28 VDC connected to it (through K4X, K4Y or K4Z) the ETR coils will then be energized.

Conversely, if the Relay Driver is "sinking" the ETR coils to ground and one of the E-Stop P/B opens, then K4X, K4Y and K4Z will de-energize and their contacts providing 28 VDC to the ETR coils will open, and the ETR relay coils will de-energize--removing the positive 125 VDC from the fuel trip solenoid outputs (all of them).

So, the closed E-Stop P/B contacts allow K4X, K4Y and K4Z to pick up, which allows 28 VDC to be applied to one side of each of the ETR coil groups. When the Relay Driver is energized (when L4_XTP is a logic "0" <b>AND</b> there is no overspeed (or the rate-of-change of speed isn't excessive) then the Relay Driver will be actuated which will "sink" the other side of the ETR relay coils to ground which will allow the ETR relays to pick up and apply positive 125 VDC to one side of the fuel trip solenoids.

Now, let's look at the seven discrete trip "interlocks". And, here's where there is a definite lack of documentation. Note that only one discrete trip "interlock" is shown, but that there are seven total. Note also that the "TRP" leg of the input goes "To JX1 JY1 JZ1"--which are references to cables connecting the TRPG to each of three VPROs (<X>, <Y> and <Z>). So, the TRP legs of each of the seven inputs go to the VPRO--not to <Q>, and somehow, in the firmware of the VPRO the state of the input is monitored and used as a "permissive" for the Relay Driver outputs from <X>, <Y> and <Z> to the ETR coil circuits (over the same cables, JX1, JY1 and JZ1). So, what appears to be happening is that the trip "interlocks" are being used as permissives (normally closed contacts) for the Relay Driver outputs from <X>, <Y> and <Z> VPROs to the ETR circuits on the TRPG.

So, this is the hardware part of the trip circuit and how it works--as best as can be determined from the information and drawings in the System Guide.

Hopefully, the above--in conjunction with the proper drawing in the System Guide--help to explain the circuits and how they all work.
 
CSA

Thank you for your detailed response,and it really helps!

1)
"Yes; you are basically correct that there are four basic ways to trip the turbine <b><i>via the Speedtronic turbine control system:</b></i>"

CSA, do you mean there are other ways to trip the turbine which is not <b><i>via the Speedtronic turbine control system:</b></i>"? Like mechanical over speed trip?


2)
<i>3) Seven (7) discrete trip inputs to TRPG which open to trip; remember these cannot be inverted, and they cannot be forced in Toolbox/ToolboxST.</i>

<i>So, the TRP legs of each of the seven inputs go to the VPRO--not to <Q>, and somehow, in the firmware of the VPRO the state of the input is monitored and used as a "permissive" for the Relay Driver outputs from <X>, <Y> and <Z> to the ETR coil circuits (over the same cables, JX1, JY1 and JZ1).</i>

CSA,i am not clear about the relationship between L4 and 7 discrete trip inputs. Are these 7 discrete inputs one part of L4T logic or they are independent of L4T? Are these 7 discrete trip inputs only monitored in <P> core? Or can we see thers logic signals via toolbox?
Can you take one example of these 7 trip inputs? I am wondering what kind of discrete inputs should be connected to TREG terminal board.
I checked on my site,and think l86tgt1 may be one of the 7 trip inputs,and it is one part of L4T logic.

3)
<i>So, what appears to be happening is that the trip "interlocks" are being used as permissives<b> (normally closed contacts)</b> for the Relay Driver outputs from <X>,<Y> and <Z> VPROs to the ETR circuits on the TRPG.</i>

You said they are normally closed contacts. Does that mean if the trip input is logic 0,then the turbine trips?

Hope i am clear this time.

Best regards!
Neo
 
Neo,

1) Yes; there are ways to trip the turbine via the Control Oil or Trip Oil system. Units with a mechanical overspeed bolt will trip via the Control- or Trip Oil systems, and some units have a manual "Trip" button or lever in the Accessory Compartment that will also trip the turbine via the Control or Trip Oil System.

2) I don't have access to a Mark VI System Guide at the present time or I would refer to the VPRO/TREG section to try to give a more concise answer. GE does some "unusual" and inconsistent things from time to time, and I believe this is one of those consistently inconsistent things--using the TREG discrete inputs in the L4T rung(s). These seven discrete trip inputs were essentially added to the TREG for SIMPLEX tripping purposes, and it was my understanding that they were not typically used for TMR applications. They were meant to be used to trip via the ETRs in the event that communication between <R> and <P> was lost--in effect, a back-up or redundant trip method. Usually, a second contact of the low-low L.O. pressure switch, for example, was wired to the TREG and used to trip the turbine in the event that <R> didn't recognize a change of state of it's low-low L.O. pressure trip discrete input.

Because there is no application code which is visible using Toolbox in <P> I believe that some individuals add the TREG discrete trip inputs to an L4T rung so that there is more "visibility" if one of them should actually trip the turbine.

I also believe that there are timed over-rides for some of these TREG discrete trip inputs because they might not be closed when a START is initiated and so a time delay is required to allow the signal to close and a START to progress.

I have done this test many years ago (perhaps philosophy or firmware has changed--but I tend to think not): I would jumper all of the TREG discrete trip inputs which were enabled on a particular Mark VI (usually one of the "skeleton" Mark VI SIMPLEX panels) and then force L4_XTP to a logic "0" to pick up the ETR relays. I would also force L20FG1X, for example, to pick up the PTRs to energize 20FG-1. Then I would open each of the TREG discrete input circuits one at a time and observe that the ETRs would drop out and 20FG-1 would drop out--and I did not observe that the PTRs would drop out (because these TREG discrete inputs were NOT used in any L4T rung). This would prove (to me) that any of the seven TREG discrete trip inputs would indeed deactuate the ETR relays, resulting in a de-energization of the fuel trip solenoid.

Again, there is no "visible" application code in <P> to observe how this works; it's just coded in firmware. I believe in an older version of the Mark VI System Guide it was documented in the firmware description of the VPRO/TREG cards, but I don't have access to that as this writing.

I don't believe it's necessary to use any of the TREG discrete trip inputs in any L4T rung to actually trip the turbine--I think it was done by some individuals because they thought it should be done. I believe that if any of the seven TREG discrete trip inputs open when the turbine is running that it will drop out the ETR relays <b><i>before</b></i> the change of state is transmitted to <Q> and processed by the application code to de-energize the PTR for the fuel trip solenoid. So, it just seems redundant (not necessarily wrong, but not necessary) to use the TREG discrete trip inputs in any application code L4T rung.

That's about the best explanation I can provide at this time.

3) As we discovered during the L4 journey, yes; the inputs must be closed during normal operation and when they open the turbine will be tripped. I don't recall the signal names but a couple of them were "inverted" (the signal name was a logic "1" when the unit was to be running, and a logic "0" when the unit was to be tripped--which is opposite of GE-design heavy duty gas turbine control philosophy). I think it was L86TGT1 or something like that in the L4 rung. And didn't we discover that one of them was "inverted" in application code??? Kind of ... unnecessary.

Again, we are dealing with engineering performed by the GE Belfort bunch, and they are pretty lax with standards enforcement, just doing what they think should be done on your application--so some of this is just to be expected.

Finally--it was my understanding that the TREG discrete trip inputs were NOT to be used on TMR applications, because of the nature of TMR controls. So, in my personal opinion using any TREG discrete trip input on a TMR application is in unnecessary, and if one does use one or more then the signal names should match

Hope this helps!
 
CSA:

Are our L4 journey completed?

Though there are a lot of stuff remain unknown, but it really improve my understanding of GT control through this L4 journey.So thank you so much!

I would like to know where should i go or what should i learn as to have a good understanding of GT control.

It would be a great honor if you share your opinion with me(us).

Best regards!
Neo
 
Neo,

I would answer no; our L4 journey is not complete, as we didn't finish all of the L4T rungs (at least I don't think we did).

As for what's next, well, that's up to you. What do you want to discuss next? We've talked about inversion masking; drop-out-to-run; signal naming. Other topics might include LVDT calibration; servo-valve operation; and so on.

It's your call. I'm ready to go where you want to take this.
 
CSA

Thank you for your response.

Yeah, you are right, L4T is not finished. But i would like to continue L4T later, as it needs a wide variety of background information. Is it OK?

For now,i would like to learn servo operation and LVDT calibration. What should i do first and should i open a new thread?

Best regards!
Neo
 
Neo,

As you wish. But, if you haven't discovered this already learning background information about anything helps one to understand how it works, why it works the way it does, and how to troubleshoot it when it doesn't work. Just knowing the thing doesn't do that. The journey we are on could be about an Allen-Bradley (Rockwell) PLC, or a Hitachi HI-ACS, or a Woodward governor control system--but to program any of those one needs to understand how the devices work and how the turbine is supposed to operate using the devices.

Discussing servo-valves without the benefit of drawings/graphics is going to be difficult, so let me think about how we are going to do that on this forum.

LVDT calibration would be easier if we had the ability to use drawings and graphics, but we can try to accomplish this without them and see how it goes.

And, always when straying from the theme of the current thread one should open a new thread.
 
Is this true ? + 125 V DC and - 125 V DC?

Not + 62.5 V DC and - 62.5 V DC ?

Please correct me if I am wrong.
 
Ann,

> Is this true ? + 125 V DC and - 125 V DC?
> Not + 62.5 V DC and - 62.5 V DC ?

> Please correct me if I am wrong.

The reference is to the positive- and negative legs of the nominal 125 VDC source, which can be higher or lower than +62.5 VDC and -62.5 VDC depending on the number of cells of the battery and the setting of the battery charger. You are correct--if the battery voltage is exactly 125 VDC <b>AND</b> there are no grounds on either leg of the battery supply.

But, it's common to use either reference (+125 VDC and -125 VDC, or +62.5 VDC and -62.5 VDC), and for batteries a nominal voltage of 130 VDC, +65 VDC and -65 VDC. That's why sometimes the reference is to just +125 VDC and -125 VDC--the nominal battery supply voltage.

Hope this helps!
 
Dear CSA

i can't see any replys since this one.
Are you and Neo changed the thread?!!!
Please feed me back...

>> Is this true ? + 125 V DC and - 125 V DC?
>> Not + 62.5 V DC and - 62.5 V DC ?
>
>> Please correct me if I am wrong.
>
>The reference is to the positive- and negative legs of the
>nominal 125 VDC source, which can be higher or lower than
>+62.5 VDC and -62.5 VDC depending on the number of cells of
>the battery and the setting of the battery charger. You are
>correct--if the battery voltage is exactly 125 VDC
><b>AND</b> there are no grounds on either leg of the battery
>supply.
>
>But, it's common to use either reference (+125 VDC and -125
>VDC, or +62.5 VDC and -62.5 VDC), and for batteries a
>nominal voltage of 130 VDC, +65 VDC and -65 VDC. That's why
>sometimes the reference is to just +125 VDC and -125
>VDC--the nominal battery supply voltage.



 
I believe Neo lost interest in this discussion and wanted to talk about electro-hydraulic servo-valves. I admit I haven't finished writing that description, having made many edits and still looking for a way to "draw" some concepts because a picture "...is [still] worth a thousand words."

If you have questions, we will try to find answers. These threads got quite long, and there are other related threads (just click on Neo's name and you will find other similar threads).
 
CSA;

Haven't seen you for long time. I have to say i never lost interest in gas turbine control logic. I have been reading CSP with the method you taught me. Furthermore, i build gas turbine models to do simulation,and i find it helps a lot in understanding control logic.

I am always willing to continue this journey if you have time and interest. It benefits many people from the world.

Best regards!
Neo
 
CSA;
In our installation we have a frame 6 with MKv TMR <I>, which runs on fuel gas only.

We've been reading this thread about hardware L4 and we found it very interesting. But we got into a question according to the voltage source P28 Vdc (Positive and Negative), for example on "<P> core in the Emergency trip push button connections on PTBA., where we see masters relays (L4), (4-1 (k22) / 4-2 (k23), 4-3 (k24), 4-4 (k25), all of them are 24 Vcc relay, but as we can see on that drawing on the TCTG CARD those relays are connected to a source of 125 Vcc. how is it possible to feed a 24 Vdc relay with 125 Vdc?

On other hand we also see on the same drawing a positive of 24Vdc which pass through the master relays auxiliary contacts, where this 24Vdc comes from? (maybe from the Transformer on the TCEA card?), we are lost with this issue.

GEH-6195B (Figure D-46)

Thank you very much in advance
 
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