When Will 88CR start?

N

Thread Starter

Neo

Hello everyone.

I was asked to read application code to know the GT startup sequence.

It is a MS6001B GT with 88HR and 88CR.

I used to think it is 88HR that get shaft break away from zero speed. When L14HR is logic 0, 88HR stops, and 88CR began to run.

So L14HR is the trigger signal to get 88HR stopped and 88CR started, but i can't see that
in application code.<pre>
L34CRY L4Y L86CRTX l33cse L14HS L4CRT l4cr
------||-------|/|------|/|--------||---------|/|--------|/|------( )
l52cr |
------||----</pre>
L34CRY = Starting Means Cranking Control Logic;
L4CRT = Starting Means St. Motor Braker Did Not Pick Up;
l4cr = Starting Means Cranking Motor Start Command Logic<pre>
l52cr L34CRY
|/|--------(T)
20sec</pre>
It am confused about L34CRY. And i am confused which is the signal that make l4ct convert to logic 1.

In my site, during cooldown,the shaft will turn around for about 47° and stop for about 3 min. if START command was sent during that 3 min, will 88CR run while 88HR is stopped?

One more question, in this situation logic 1 is to get motor started. but i have seen logic like l4qez and l4hqe, when they are logic 0, the pumps will get started. I am confused about that. And how can i deduce it is logic 0 or 1 that will get motor started.

Above are the questions i have to ask master like CSA and others, thx.

CSA, i will continue the L4 journey later,sorry. I am a little exhausted with my job.

Best regards!
Neo
 
Hi, Neo,

I'm a little confused about where to pick up with the L4 journey at this point.... I know you have some questions, but, as with this post there are typographical/spelling errors which I find it difficult to work through.

For a Frame 6B the starting sequence should be that when a start is permitted ('Ready to Start' is a logic "1") and a START is initiated that the hydraulic ratchet mechanism will start first to ensure the jaw clutch is engaged to prevent the starting means from rotating the starting means side of the jaw clutch while trying to engage the jaw clutch (the jaw clutch teeth can be damaged if this happens). The ratchet needs to engage the clutch before the starting means starts spinning the starting means half of the clutch.

At any rate, once the clutch is engaged the starting motor should start and torque can be transmitted from the starting means to the turbine-generator shaft. BUT, the hydraulic ratchet is still energized and active during a START--not waiting three minutes between strokes--because the starting means by itself cannot break the shaft away from zero speed, it requires the "bump" from the ratchet mechanism to break the shaft away from zero speed. As soon as the shaft breaks away from zero speed (when L14HR goes to a logic "0") then the hydraulic ratchet should be stopped (the torque from the starting means accelerating the turbine-generator shaft) will keep the clutch engaged (the hydraulic ratchet is not required to be running to keep the clutch engaged when the shaft is being rotated by the starting motor).

Now, let's look at the logic you've provided, and some of the "interactions" between the signals. First, l4cr (the lower-case alpha characters indicates it's an input or output--probably the name of the discrete output that operates the starting motor breaker) and l52cr (again, the lower-case alpha characters indicates it's an input or output--it's the status input from the starting motor breaker) are related. So, when l4cr goes to a logic "1" and there is no problem with starting motor protective relay then l52cr will very quickly go from logic "0" to logic "1" to indicate the starting motor is (should be) running (because the starting motor's starter breaker is closed).<pre>
l52cr L34CRY
-----|/|--------(T)
20 sec</pre>
So this rung basically says that when l52cr is NOT a logic "1" for more than 20 seconds then L34CRY will go to a logic "1". So, under normal circumstances, 20 seconds after l4cr goes to a logic "0" (and l52cr goes to a logic "0"), then L34CRY will go to a logic "1".

And then here's l4cr:<pre>
L34CRY L4Y L86CRTX l33cse L14HS L4CRT l4cr
------||-------|/|------|/|--------||---------|/|--------|/|------( )
l52cr |
------||----</pre>
Reading this rung it says: When the cranking motor breaker <b>IS NOT</b> closed for 20 seconds then L34CRY will be a logic "1" and if L4Y IS NOT a logic "1" and L86CRTX is NOT a logic "1" and l33cse IS a logic "1" and L14HS IS NOT a logic "1" and L4CRT IS NOT a logic "1", then l4cr will go to a logic "1". Or, in other words:

<b>When the starting motor breaker has not been closed for more than 20 seconds AND when L4Y IS NOT a logic "1" AND there is no starting motor protective lockout AND when the starting clutch (jaw or SSS) is engaged and when the unit is NOT at synchronous speed and when there is NOT a starting motor trip then l4cr will go to a logic "1". And when l52cr changes state from logic "0" to logic "1" then it will "seal in" around L34CRY to keep l4cr picked up (a logic "1") until the clutch opens (l33cse goes to a logic "0").</b>

Let's refer to L4Y (AGAIN):<pre>
L4 L4Y
------|/|---------(T)
1.0 sec</pre>
L4Y is a logic "1" when L4 has NOT been a logic "1" for more than 1.0 second.

<b>L4Y will be a logic "0" when L4 >>>IS<<< a logic "1".</b>

So, l4cr needs L4Y to be a logic "0" when there is no starting motor lockout trip and no starting means trip and the unit is below 14HS and the clutch is engaged to pick-up, and L4Y will be a logic "0" <b>as soon as L4 goes to a logic "1".</b> And L4 will go to a logic "1" when a START is initiated and enabled.

Basically, l4cr, under normal circumstances and when the turbine shaft speed is less than L14HS drop-out, is just "waiting" for l33cse to be a logic "1" <b>AND</b> for L4Y to go to a logic "0"--and then l4cr will go to a logic "1"--and the starting motor will be started.

So, writing a statement (sentence) and understanding each and every signal in that statement is key to understanding ("reading") the rung. In this case, it was key to <i><b>remember</i></b> that L4Y is a function of L4 (an "inverse" function) and that is the key to understanding when l4cr will go to a logic "1" during a START. If the unit has been on ratchet--either "actively" or before COOLDOWN OFF was selected--the clutch should be engaged, so l33cse should be a logic "1" under most circumstances when the unit is at zero speed (or on COOLDOWN). And, l4cr is just waiting for L4Y to go to a logic "0".

I promise--if you will learn to write a proper sentence (statement) for any rung you are trying to understand you will quickly learn how to read rungs WITHOUT writing a sentence statement. Sometimes, as in the case of L4Y in this rung, it's not the ACTUAL signal but the logic driving the signal (in this case, L4 drives L4Y). Writing a sentence (statement) trains you to think in relay ladder diagram "language" so that, soon, you will not need to write the sentence (statement)--you will just be able to read the statement as you are working from left to right looking at the elements of the rung. I <b>promise.</b> While it seems difficult and "unnecessary" it's about the only way I know of to train one's mind to "read" logic (relay ladder diagram or function block diagram).

Alternatively, you can write the rung on a piece of paper and then write the condition which makes the element <b>CLOSED</b> in order to understand when the rung's coil is energized (a logic "1"). But, I don't know of any way (except for really smart, intelligent and quick learning people) to learn to read logic without writing it out, as many times as it takes. I <b>still</b> occasionally have to write a rung out--especially when I'm looking at Mark VI Toolbox or Mark VIe ToolboxST logic--because it's just confusing the way it's depicted in the Toolbox or ToolboxST application. But, as soon as I write it out--it becomes OBVIOUS exactly how the rung works (or doesn't!).
 
CSA

Thank you so much for your reply. Your detailed response always helps!

I think the way your think is remarkable,and i should learn about that.

Thank for your "Writing a proper sentence for any rung" advice, i will keep on practicing.


BTW, sorry for the mistakes and errors in L4 journey. I will do better later.

I think you are clear about what should be covered in this L4 journey, and you can ask me to do that, and then make a comment.

As you say, we are not quitters, and we will back on L4 journey. Just take that we are now having a rest during this long journey.

Anyway, we are not in hurry.

Thanks again!

Best regards!
Neo
 
Neo,

There was another query in the original post, and we'll get to that in a moment.

I would like you to post the L4CRT rung, if you would, please. I'm curious to know if it's been changed from what it's been for decades--based on the Longname description.

Now, as for understanding discrete output signal names. Many discrete outputs drive motor starters, and GE deems some of these motors to drive "critical" devices (the definition of critical, is, of course, completely at GE's discretion!). So, many logic signals driving discrete outputs will start with 'l4', and many of them will end with a suffix of 'z' or 'z1' or '1z' or something similar (again--they are consistently inconsistent with signal naming!).

The 'l4' part of the signal name stands for 'Master Control'--and that translates to 'Start & Stop' for a motor starter control circuit. While many manufacturers and programmers will use two contacts--one to start and one to stop a motor--GE heavy duty gas turbine control philosophy is that only one contact shall be used for <b>both</b> start and stop.

So, let's take the Aux. L.O. Pump motor, 88QA, as an example. The logic signal which starts and stops the 88QA is l4qaz. The 'z' stands for 'zero'--meaning that when the signal is a logic "0" the motor is to start and run, and when the signal is NOT a logic "0" (when it's a logic "1") the motor is to stop.

This is done by using a normally CLOSED contact of the discrete output's electromechanical relay (the logic signals drive individual electromechanical relays of the Speedtronic turbine control panel by energizing and de-energizing the relay's coil) in the AUTO circuit of the Aux. L.O. Pump's motor starter control circuit. So, when the logic signal l4qaz is a logic "0" the discrete output relay coil is de-energized ("dropped out") the normally closed contact will be CLOSED and this will pick-up (energize) the contactor of the Aux. L.O. Pump Motor's starter, applying 440 VAC to the motor's terminals. This is what GE calls "drop-out-to-run" control philosophy, and the Aux. L.O. Pump is considered to be a critical device.

To stop 88QA, the logic signal l4qaz has to go to a logic "1" which will energize the discrete output's relay coil which will pick up the relay and open the normally closed contacts in the motor starter's AUTO circuit to de-energize the contactor's relay coil and remove the 440 VAC from the motor's terminals.

Why does GE do this? Well, there are several reasons--but the foremost reason is that the predominant failure mode of electromechanical relays is to fail in the de-energized state. So, let's say that a normally OPEN contact of a discrete output is used to start and stop the Aux. L.O. Pump's motor. This means that to start the pump motor the logic signal has to go to logic "1" to close the normally open contacts of the Speedtronic's discrete output relay and energize the contactor coil of 88QA to start the motor. But, let's say while the Speedtronic is telling the motor to be running the electromechanical relay of the discrete output fails, that would mean that the normally open contacts would open and 88QA would stop. Not so good if you need L.O. to lubricate the bearings.

Or, let's say that the Speedtronic wants to start the Aux. L.O. Pump, and the logic signal driving it goes to a logic "1" BUT the electromechanical relay has failed and won't pick up. In this case, the Aux. L.O. Pump motor will not start and run. Again, not so good if you need L.O. to lubricate the bearings.

So, GE's thought process is this: If electromechanical relays fail predominantly (the majority of the time) in the de-energized state and it's critically important that the device (in this case the Aux. L.O. Pump) start and run under certain circumstances then they will use a normally CLOSED contact of the electromechanical relay to start the motor so that when the relay does fail the normally closed contact will close and start the motor.

"But!", you say, "If the relay has to be energized to stop the motor and de-energized to start the motor, and the relay fails in the de-energized state when the motor is to be stopped (when the relay is energized) then the motor will start and run when it shouldn't be running!" And you would be 100% correct--except, what harm does it do to run the Aux. L.O. Pump when it's not supposed to be running? None. What harm does it do if the Aux. L.O. Pump does NOT start when it's supposed to? A LOT!

So, they choose to de-energize electromechanical relays used for discrete outputs to close normally closed contacts driving critical devices to start the devices.

This has a LOT of benefits. Let's take the example of a running turbine that has a long-standing 125 VDC Battery Ground--a very hard ground on the negative leg of the 125 VDC. And, let's say that the Speedtronic has been configured to energize discrete output electromechanical relays to close normally open contacts to start critical motors. All of a sudden a hard ground develops on the positive leg of the 125 VDC--WHAM! The Speedtronic loses power as lots of fuses in the power distribution circuits blow (or breakers trip, as the case may be). Now, the turbine will trip and it will be coasting down. The bearings NEED L.O.! If the electromechanical relay used for the discrete output starting and stopping the Aux. L.O. Pump has to be energized to close a normally open contact of the relay to start 88QA--it can't! There is no power to energize the discrete output's relay coil to close the normally open contacts--and therefore the Aux. L.O. Pump will NOT start. Very bad things can happen, right?

But, if a normally closed contact of an electromechanical relay is to start 88QA and the Speedtronic lost power, then the relay would be de-energized, closing the normally closed contact of the relay and starting the Aux. L.O. Pump motor! Pretty ingenious, eh? (I think so! And I don't know why more manufacturers don't do this.... Well, one reason is because most manufacturers choose to use solid-state relays to drive critical outputs (newer technology than those old-fashioned electromechanical relays GE still uses!), and solid-state relays fails as often in the energized state as the de-energized state--in fact, the failure mode of solid-state relays can't be reliably predicted! But, it's newer technology than GE is using--they're so behind the times! (NOT!!!))

Anyway, drop-out-to-run ensures that when an electromechanical relay used for a discrete output fails that the device it is driving will start and run--even when it shouldn't. Is it harmful if a Turbine Compartment Vent Fan starts running when it shouldn't? No. But, if it won't start and run when it should it could be a big problem. Reliability--that's what GE is all about (right after making profits--which any corporation is formed to do). That's why they continue to use those old-fashioned electromechanical relays for discrete outputs instead of those new-fangled solid-state relays: Because the predominant failure mode is known (can be reliably predicted) and so the control system can be made as reliable as it can be.

The 'z' in the signal name, again, tells the reader that when the signal is a logic "0" the device is to start and run, which means that when the signal is a logic "1" that the device is to stop.

A motor/device that starts and runs when it's not supposed to because it is configured using drop-out-to-run logic is also 'self-troubleshooting' in the sense that it tells the conscious operator and technician that the electromechanical relay has failed and needs to be replaced. Again, it's not a problem if these devices start and run when they're not supposed to and so when the do start and run when they're not supposed to it means something is amiss. If the relay had to be energized to start and run a critical device and the relay failed and it needed to start and run--it won't. Which is kind of an indication of a fault in itself, but, to my mind not as simple to troubleshoot.

The '1z' or 'z1' indication is usually used to indicate this signal is one of two signals for redundant devices, so there will usually be a '2z' or 'z2' indication. For example, if there are two Turbine Compartment Vent Fans, there might be a l4btz1 and a l4btz2, or a l4bt1z and a l4bt2z. The 'z' in the 'l4xxxx' indicates the signal is a drop-out-to-run signal, and the number indicates which of a two or more redundant/similar outputs the signal is associated with.

Does this help?

There's more to this discrete output naming, but this should be enough for you to consider and ask any questions for clarification.

I tried to "draw" a representation, but it's not easy; sorry.

So, please post the L4CRT rung so we can analyze it, and ask any questions you need for clarity. REMEMBER: Critical is defined by GE. (Many plant managers consider EVERY motor and device to be critical--like the starting motor. But, GE considers something to be critical if it's necessary to keep the unit running at rated speed and producing power and/or is necessary for turbine/unit protection. There are lots of arguments for and against "criticality"--but GE's definition wins!
 
CSA:

Thanks a lot. Again it helps a lot!
And i find l72qez is different from others,as others are like "l52xx".

It is my pleasure to post L4CRT:<pre>
l4cr l52cr L4CRT
-------||------|/|--------(T)</pre>
It is said that when 88CR failed to start, then L4CRT will go logic 1.

<pre>
L34CRY L4Y L86CRTX l33cse L14HS L4CRT l4cr
------||-------|/|------|/|--------||---------|/|--------|/|------( )
l52cr |
------||----



l52cr L34CRY
-----|/|--------(T)
20 sec</pre>
CSA, what is the function of L34CRY? 34: MASTER SEQUENCE DEVICE

It seems that 88CR cannot be started within 20 sec from the second 88CR was stopped.

Best regards!
Neo
 
Neo,

You used to use the Thumbs Up/Thumbs Down indicator when you found the post useful or helpful....

Hmmm, l72qez, well, that input has caused more disagreements with colleagues than just about any other (except for humidity sensor/monitor commissioning). (GE distinguishes--sometimes--between AC and DC starters/contactors. They deem an AC starter/contactor to be a '52' device, and most of the time they deem a DC starter/contactor to be a '72' device. I say most of the time, because many times the Hyd. Ratchet contactor is referred to as l52hr, when it should be l72hr.) The signal is supposed to be a logic "0" when the Emer. L.O. Pump is running. And, so it's necessary to use a normally closed auxiliary (status) contact of the 88QE motor starter that is CLOSED when the Emer. L.O. Pump motor is NOT running, and opens when the Emer. L.O. Pump motor IS running. So, when the Emer. L.O. Pump motor starts and IS running the normally closed contact OPENS and l72qez goes to a logic "0" (the 'z' suffix in this case means 'zero' as in logic "0"--so the signal name is a logic "1" when the Emer. L.O. Pump motor is NOT running, and a logic "0" when it is running.

The reason a normally closed contact is used is to ensure that if an open occurs in the circuit an alarm will be generated.

I've seen people put inversion masks on the input, and change the contact sense from normally closed to normally open AND put an inversion mask on the input, and make all kinds of changes in the application code/logic/sequencing to get this to work "correctly"--but no inversion mask is necessary or required. And, I have seen Emer. L.O. Pump motor starters come wired with normally open contacts for this input instead of normally closed contacts. REMEMBER: "The circuit is to be closed under NORMAL conditions; open to alarm or trip." Under normal conditions, the Emer. L.O. Pump is NOT running, so we want a normally closed contact. Since the signal name is l72qez, without an inversion mask it will be a logic "1" when the Emer. L.O. Pump motor is NOT running, and it will be a logic "0" when the Emer. L.O. Pump motor IS running (which "matches" the signal name--'z' for logic "0" when the Emer. L.O. Pump motor IS running).

It would be very interesting to know how your l72qez signal was commissioned.... Is it inverted? Is the contact normally open or normally closed? What does the 'Emer. L.O. Pump Running' alarm rung look like in the application code at your site? (I'm always curious about this, because, it's caused so MUCH controversy and so many loud arguments over the years.)

The other motor starter status signals are pretty much straightforward: l52cr is a logic "1" when the starting motor's starter is energized and the starting motor is supposed to be running; l52hq is a logic "1" when the Aux. Hydraulic Pump motor started is energized and the Aux. Hyd. Pump is supposed to be running; l52qa is a logic "1" when the Aux. L.O. Pump motor starter is energized and the Aux. L.L. Pump is supposed to be running.

<b>L4CRT:</b><pre>
l4cr l52cr L4CRT
-------||------|/|--------(T)</pre>
Well, this is a change from previous years; and an interesting one, at that. Why is it necessary to put a timer on the status of the starting motor's motor starter? Hmmm..... Because, one would think that when l4cr goes to a logic "1" that within less than 1 second the motor starter would pick up and l52cr would change state. So, I wonder if l4cr goes to some other control system which has some permissive(s) to allow and then to actually energize the starting motor's motor starter, and so because of the delay it was necessary to add a timer to wait for the starter to pick up??? And, to call it L4CRT... To me, the 'T' means 'trip' and the L4 means a Master Control element. A better name might have been L2CRF: "Cranking Motor Failure to Start." But, nobody asked me, so, it is what it is, right?

AND, does L4CRT drive an alarm???? If so, what does the alarm text message say?

>CSA, what is the function of L34CRY?
>34: MASTER SEQUENCE DEVICE

I was wondering if you were going to ask about L34CRY. (I'm pleased you picked up on that!). I've never seen the device number 34 used in GE heavy duty gas turbine controls before, so this is very new to me. And, I wonder: What's the difference between a '4' device and a '34' device? I guess the '4' is a Master <b>Control</b> device, and a '34' is a Master <b>Sequence</b> device....

It would seem that there is something unusual with the starting motor motor starter and/or its control circuit, because this bit of logic does, indeed, say: The starting motor can't be re-started within 20 seconds of a previous start. Now, some large, high-voltage AC motors are not supposed to be started multiple times in very quick succession. The high current drawn on inrush during starting, if started several times in quick succession, can damage the motor. So, for example, 4160 or 6600 VAC motors usually have some protection to limit the number of starts to two or three per hour--to protect the motor. Or, the operators and their supervisors are supposed to know not to start these motors more than two or three times per hour (though many don't know that...). So, my guess is there's something unusual about this motor starter's control circuit and these two timers (L4CRT and L34CRY) are required for some kind of supervision or protection.

And, a better signal name for l34CRY would have been 'L52CRY' because it's only an inverse timer on the motor status--it's not a "sequence" device, it's just a timer that prevents a rapid "re-start". Again, there's something unusual about the starting motor's motor starter/protective circuit.

So, I think that about covers it! Please--check to see if there's a Process Alarm for the starting motor failing to start in some period of time (and, by the way, what is the timer value for L4CRT?), and if there is, post the alarm text message, please.

Also, can you determine if l4cr acts directly on the starting motor's motor starter coil, or does it pass through some other control system/protection circuit?

Lastly, can you determine how l72qez is configured at your site (normally open or normally closed contact; inverted or normal; what does the process alarm rung look like)?

Thanks!

Good on you, by the way; there's hope for you, yet.
 
CSA:

To be honest, every of your response helps!

"Lastly, can you determine how l72qez is configured at your site (normally open or normally closed contact; inverted or normal; what does the process alarm rung look like)?"<pre>
L14HSZ l72qez L72QEZ_ALM
----||-----------|/|---------( )</pre>
When GT is under normal operation, and the emergency lube oil pump is running,there will be emergency lube oil pump in operation alarm.

I find l72qez is not inverted,and it is a NC contact.

BTW,I found there is no l52hr signal.

"by the way, what is the timer value for L4CRT"
K4CRT = 2sec<pre>
l4cr l52cr L4CRT
-------||------|/|--------(T)
2sec</pre>
CSA, i think there should be a timer, because the starter cannot be running as soon as it is asked to.

"Also, can you determine if l4cr acts directly on the starting motor's motor starter coil, or does it pass through some other control system/protection circuit?"

l4ct acts directly on the starting motor's starter coil.

CSA,i find L4CRT in L3SMT rung.
<b>part of L3SMT rung</b><pre>
L4CRT L14HSX L94X L3SMT
------||-------|/|-----|/|-------( )
|
......... |</pre>
L3SMT = Starting means device trip;

So when 88CR fail to start, GT is blow operation speed, and GT is not under normal shutdown, then L3SMT will go to logic 1.

I think that maybe the reason why there is a "t" suffix in L4CRT signal.

CSA, is it ok? if there is anything you want to cover, i would like to do as your command.

Best regards!
Neo
 
CSA:

Can i ask questions about L1X, L1Z and l4hr.

I am just wondering whether L1X goes to logic 1 first or L1Z goes to 0 logic first. And is it L1Z signal that trigger l4hr goes to logic 1?

And when will L1X goes to logic 0.What is the difference in application code between cooldown at startup and shutdown.

If it is ok, i would like to post rung.


Best regards!
Neo
 
Neo,

You don't have to ask--no one does!

I wouldn't comment until you posted L1x and L1Z from the application code in your Mark VIe anyway.
 
CSA:

I am preparing for the L1Z, L1X, l4hr rung.
And i think you may miss one of my response.

Best regards!
Neo
 
Neo,

Can you repeat question/response, please?

I don't want to comment on L1X, L1Z until you post the rungs from the application code in the Mark VIe at YOUR site.
 
CSA

I would like to begin with L1Z,and i think it is a little hard for me. I will do as much as possible.<pre>
L1ZX L43CDON L1X L14HR L1Z
--------||------|/|------|/|-------||--------( )
L1Z |
--------||----</pre>
L1Z = turbine Auxiliary On Cooldown. Drop Out Signal;
L1ZX = Auxiliary to L1Z Master Control Relay;

I think when we are referring to cooldown,there are <b>startup cooldown</b> and <b>shutdown cooldown</b>.
I would like to talk about <b>startup cooldown</b> first.

Before Cooldown On,L1Z should be logic 1. When operator select <b>Cooldown On</b>,L43CDON will pick up for one second (a pulse).
And L1Z will drop out. When L1Z goes to logic 0,88QA and 88HR began to run. (I am wondering whether 88HQ and other auxiliaries should be running too?)

In order to keep L1Z logic 0, L1ZX should be logic 0.

I am confused about the existence of L1X and and L14HR. Is it intended to keep 88QA running before L14HS goes to logic 1?<pre>
L1STOP L43CA L62CD L43CDON L1Z L1ZX
-------||-----||------||------------|/|----|/|------( )
L43CDOFF L62CD |
-------||-----||-------------
L1ZX |
-------||---------------------</pre>
L43CA = Cable Remote Selected On;
L62CD = Cooldown Complete;

I think under normal situation L1ZX should be logic 0.

When "Cooldown is on"and Cooldown is Complete after shutdown cooldown, and operate selects <b> Cooldown Off</b>,then L1ZX will
go to logic 1, and l1Z will go to logic 1. So, cooldown will stopped. And as soon as L1Z goes to logic 1, L1ZX drops out.<pre>
L1STOP L43CA L62CD
-------||-----||------||-----</pre>
I am not clear about which situation the above rung refers to?

CSA, i find L1Z rung is difficult to read, it is hard to sort it out. L1Z and L43CDON in L1ZX rung makes it more difficult to read.

I am not clear why L43CDON and L1Z are included in L1ZX rung.
 
Neo,

You didn't post L1X.... It's kind of critical to the whole discussion. And, it's also kind of complicated (not really) so we're probably better off without it for now.

Let's start with L1Z (as good a place as any to start!). When L1Z is a logic "0" then the auxiliaries will start and run (most specifically the Aux. L.O. and Aux. Hyd. Pumps during starting, and also the Hyd. Ratchet Pump after the unit has coasted down and reaches zero speed). L1X goes to a logic "1" during starting when the START command is initiated by the operator and "accepted" by the Speedtronic (i.e., a 'Ready to Start' is enabled).<pre>
L1ZX L43CDON L1X L14HR L1Z
--------||------|/|------|/|-------||--------( )
|
L1Z |
--------||----</pre>
So, prior to a START L14HR is a logic "1" and L1Z is a logic "1" and L1ZX is a logic "0" (We'll get to that below--but for now, just work with me.) When a START is accepted, L1X picks up and drops out L1Z. I believe L1X stays a logic "1" until the unit reaches FSNL or the generator breaker closes (it differs depending on vintage of the machine). At any rate, when L14HR goes to a logic "0" when the shaft starts spinning, L1Z CANNOT go to a logic "1"--it's always a logic "0" any time the unit is above zero speed (because L14HR is a logic "0").

Now, for L1ZX.<pre>
L1STOP L43CA L62CD L43CDON L1Z L1ZX
-------||-----||------||------------|/|----|/|------( )
|
L43CDOFF L62CD |
-------||-----||-------------
|
L1ZX |
-------||---------------------</pre>
L43CA = Cable Remote Selected On
L62CD = Cooldown Complete

L43CA, "Cable Remote," refers to the REMOTE of OFF, CRANK, FIRE, AUTO and REMOTE. Most combined cycle units have this (REMOTE) for control from the DCS.

L62CD is the timer that prevents the operator from taking the unit off Cooldown before it's had time to cool so the axial compressor rotor won't bow (sag). When the Cooldown Timer has expired, then Cooldown is said to be "complete" and Cooldown OFF can be selected to stop the Hydraulic Ratchet.

Now, let's say the unit is coasting down from a trip or a STOP. L1Z is a logic "0" (because L14HR is a logic "0" which prevents L1Z from picking up). L1ZX can't go to a logic "1" until:

1) L1STOP goes to a logic "1" <b>AND</b> L43CA is a logic "1" <b>AND</b> L62CD is a logic "1" <b>AND</b> L43CDON is <b>NOT</b> a logic "1" and L1Z is a logic "0"

<b>OR</b>

2) L43CDOFF is a logic "1" <b>AND</b> L62CD is a logic "1" <b>AND</b> L43CDON is <b>NOT</b> a logic "1" and L1Z is a logic "0"

<b>OR</b>

3) L1ZX is a logic "1" <b>AND</b> L43CDON is <b>NOT</b> a logic "1" and L1Z is a logic "0". (This is the "seal-in" that keeps L1ZX picked up when either of the two conditions above have picked up L1ZX.)

So, let's look at the three conditions that will make L1ZX a logic "1":

1) Operator initiates a STOP <b>AND</b> "Cable Remote" is selected and active <b>AND</b> the Cooldown Timer has expired <b>AND</b> Cooldown ON is NOT selected and active <b>AND</b> L1Z is a logic "0". This says that when REMOTE is selected and enabled <b>AND</b> the Cooldown Timer has expired <b>AND</b> a STOP is initiated by the operator <b>AND</b> Cooldown ON is not a logic "1" <b>AND</b> L1Z is a logic "0" then L1ZX will go to a logic "1". So, the operator can take the unit off Cooldown when the unit is in REMOTE if a STOP is initiated (be it from an HMI or from the DCS)--whatever picks up L1STOP. This is so there doesn't have to be a COOLDOWN OFF selection from the DCS--the operator can just initiate a STOP from the DCS when the unit is in REMOTE mode and if the Cooldown Timer has expired the unit will go off Cooldown. HOWEVER--if someone clicks on STOP from an HMI when REMOTE mode is selected, well, then that also picks up L1STOP and that will also take the unit off Cooldown. HMI functions are still enabled and active when REMOTE is selected. Selecting REMOTE only enables the 'remote' operation (from the DCS, for example)--it does NOT disable the HMIs. (This surprises a LOT of people--and it's NOT documented anywhere....)

<b>OR</b>

2) The Cooldown Timer has expired <b>AND</b> the operator initiates COOLDOWN OFF from the HMI <b>AND</b> Cooldown ON is not a logic "1" <b>AND</b> L1Z is a logic "0". This is how the operator would take the unit off Cooldown from the HMI ("Local" control).

<b>OR</b>

3) L1ZX is a logic "1" <b>AND</b> Cooldown ON is not a logic "1" <b>AND</b> L1z is a logic "0". (Again, this is the "seal-in" that keeps L1ZX picked up when either of the two conditions above have picked up L1ZX.)

So, when COOLDOWN OFF is selected and the Cooldown Timer has expired then L1ZX will go to a logic "1" which will cause L1Z to go to a logic "1". <b>OR</b>, if the unit is in REMOTE and the Cooldown Timer has expired and the operator issues a STOP from the DCS (or clicks on STOP on an HMI) then L1ZX will go to a logic "1" which will cause L1Z to go to a logic "1" which will shut down the Aux. L.O. Pump and the Hyd. Ratchet Pump. When L1Z goes to a logic "1" that will drop out L1ZX.

To start Cooldown when the unit is at rest, the operator clicks on COOLDOWN ON which picks up L43CDON which causes L1Z to go to a logic "0". <b>OR</b> when a START is initiated and L1X goes to a logic "1" then L1Z will go to a logic "0".

The thing about L1Zx is that it's never a logic "1" for very long--that's because L1STOP isn't a logic "1" for very long (when the unit is at rest!), and L43DCDOFF isn't a logic "1" for very long (it's just driven by the target on the HMI, which is only usually 1 second). Even when it "seals itself in" it drops out when L1Z goes to a logic "1", which breaks the seal-in and it goes right back to logic "0". L1ZX is really only used to stop Cooldown (when the Cooldown Timer is expired). It goes to a logic "1" for a brief period of time, which picks up L1Z, and when L1Z picks up, then L1ZX is dropped out. Does that help understand it better?

You seem to be experiencing some kind of issue with Cooldown..... Or, someone believes Cooldown should do this or that and you're trying to confirm it (or correct them). If you could tell us what the issue you're trying to understand is, we might be able to explain it by looking at the rungs.

L1X is also going to be kind of complicated; there's usually and L1XX and an L1XX1, and they're all messy, too. But, they good to know and understand. This is really some of the trickiest logic in the Speedtronic. It's deceptively simple, yet can be very confusing. (I've seen this logic re-written by someone who wanted to make it easier to understand--but it took about eleven (11) more rungs to do all of this--and while it was a little easier to understand, it took a long time to piece it all together.

This is one of those where you just have to roll up your sleeves and get to a quiet place where you're not worried about time and schedules and make a LOT of notes on paper until you get it all down. Again, writing out the rungs is good; not always easy, but good.

I've read and re-read and re-re-read and proofread and re-proofread this several times and I hope there are no errors. But, I make no guarantees.
 
CSA:

Thank you so much for your detailed and helpful response. After reading your response carefully and rethinking the L1Z rung, it become much more clear to me.

The way you think really impress me, and i think i should learn about that.

I read L1Z and L1X rung just to know how is the GT controlled by the application code during startup.<pre>
L3RS L1S L4 L1XX L5EX L3SFLT L1X
---||------||-------||--------||------|/|----|/|------( )
L14HT | | L4Y |
---||---- |----||-----
L1X |
-------||-------</pre>
L14HT = Cooldown slow roll start speed relay
L5EX = Emergency Manual Trip Command Auxiliary

1) I think<pre>
L4
------||------
| L4Y |
------||-----</pre>
is to drop out L1X when L4 drops out.

2) When L1X pick up,auxiliaries starts running. When L1X drops out, will auxiliaries stopped running?

It seems not. When L4 drops out, and drops out L1X, auxiliaries need to keep on running. So when you read L1X in a rung, what first occurs to your mind? When L1X = 1, what it stands for?

3) L1X can be pick up only when L3RS picks up or L14HT picks up. The L14HT logic in the L1X rung confuses me.

What situation it refers to?

4)L5EX is a interesting signal, for it is said that it is a trip signal, but it only appears in L1X rung, not L4T rung.<pre>
L94X L2G L62TT2 L3ACS L83BW l5051crt L1XX
------|/|------|/|-----|/|-----||-------|/|----------|/|-------( )
| |
| L4 |
|--- ||---|
| L4Y |
|----||---|</pre>
L1XX = Start Up Permissive To L1X
L2G = Generator breaker reclosing timer

I think the main function of L1XX is to drop out L1X.
SO when L94X is logic 1, L4 is logic 1, L2G is logic 1, L3ACS is logic 0, or l5051crt is logic 1, then L1XX is logic 0, and that drops out L1X.

Best regards!
Neo
 
Neo,<pre>
> L3RS L1S L4 L1XX L5EX L3SFLT L1X
>---||------||-------||--------||------|/|----|/|------( )
> L14HT | | L4Y |
>---||---- |----||-----
> L1X |
>-------||-------</pre>
>L14HT = Cooldown slow roll start speed relay
>L5EX = Emergency Manual Trip Command Auxiliary

You asked about L14HT; I think if you look for that signal in the application code you will not find it is used (or it's not used in very many places). That's typically for larger machines that use turning gear or L.O. flow through the torque converter for Cooldown, so I'm very surprised to find it used in this Frame 6B application code (but not shocked, because, after all, we are dealing with GE Belfort "logic"/reasoning). So, that part of the rung is probably unnecessary. (L14HT will likely appear in the application code in the speed level block, but the signal probably won't appear anywhere else in the application code--except here, unless GE forget to delete it from other rungs. I believe you will find TNK14HT1 and -2 set to something like TNK14HR1 and -2 in order to make it work properly in this rung (and possibly other rungs).)

L5EX is a logic signal in application code that's driven by the E-stop emergency push-button string, l5e (or at least it should be). The E-stop P/Bs are connected to the TREG card (or at least they should be) and drop out the Emergency Trip Relays to trip the turbine directly by closing the fuel stop valve(s) by removing the positive leg of 125 VDC from the fuel stop valve solenoid coil(s). L5EX is used where it's desired to use the E-Stop P/B string to stop/trip other functions--but not the turbine directly by closing the fuel stop valve(s).)

>1) I think<pre>>
> L4
> ------||------
> | L4Y |
> ------||-----</pre>>is to drop out L1X when L4 drops out.

Yes, but L4Y is necessary to get L1X to pick up when L4 is dropped out (such as during STARTing).

>2) When L1X pick up,auxiliaries starts
>running. When L1X drops out, will
>auxiliaries stopped running?

You will have to look at the auxiliaries (the Aux. L.O. Pump and Aux. Hyd. Pump and Hyd. Ratchet Pump rungs to see what drops them out (I don't think we've looked at l4hr yet.... And we can also look at l4qaz and l4hqz if you want--later.)

>When L1X = 1, what it stands for?

It's part of the starting sequence; most importantly it's part of the L1Z logic, right? To me, that's really the function of L1X--to pick up to drop out L1Z, and to stay picked up (during a normal START) until the unit gets synchronized (because, isn't that the purpose of starting a generator-drive GE-design heavy duty gas turbine?). Perhaps it's because I've read GE relay ladder logic for so long that I don't have expectations about what signals do; sometimes their functionality can be very limited (refer to L1ZX, for example, which is only a logic "1" for a very limited time under very limited circumstances and is just basically used to pick up L1Z--which is what really drives critical auxiliaries).

L1XX is part of the logic that prevents a START from occuring if there are problems, and "aborts" a start if there are problems, and, drops out L1X when EITHER L3ACS drops out (sometimes it can drop out sometimes after firing, but that's a very unusual occurrence) OR L2G picks up (which is some time after 52G closes (look at L2G for details)). So, it's not just for dropping-out L1X.

Again, if you're thinking you can just use the longname descriptions of signal names to understand what the signal is/does, stop. We've already learned those signal descriptions can be very misleading, even downright wrong. Yes; it's a crying shame they can't be more accurate--but that's life. Every word can have many meanings, and it's the context of the usage of words that's important--and that applies to logic signals, as well. We have agreed that relay ladder logic is a "language" and can be interpreted and read as such. So, if you're thinking that L1X is required to run "auxiliaries", then examine the auxiliaries to see what's required to start them and keep them running. I think (I'm pretty certain, actually) you'll be surprised.

Once you get more accustomed to this, you will quickly learn why GE has done this. Think about what happens if the turbine control system loses power and then power is re-applied. In this condition, the control system doesn't know what the turbine has been doing before power was applied, so it "defaults" to Cooldown on to protect the turbine, presuming the shaft is hot and needs to be protected against bowing. So, L1Z is dropped out during control system power-up, and needs to be picked up to shut down the auxiliaries and take the unit off Cooldown (after L62CD has "expired" (hint, hint!)).

You see--there is a reason for everything. Wait until you try to understand the sequencing/logic for lead/lag selection! That's really maddening for many people--until you realize it has to be "initialized" or "defaulted" on power-up of the control system, and so that's why it's so "backwards" for so many people. (We are NOT going to get into lead/lag logic; not for a LONG time. It works, and that's all anyone needs to know about it. It will mess with your mind, and is a very high-level bit of application code best left for advanced learning. It's really cool code--but it's mind-bending. And, again--we ain't going there any time soon.)
 
CSA:

Before reading your last response, I want to ask another question. I have this discussion with my colleagues for several days, but cannot figure it out.

It seems that it is not a difficult question.

<b>During startup is FSR mostly decided by FSRSU or FSRACC?</b>

All i know that during startup, firing FSR and warmup FSR is decided by FSRSU. We refer to startup curves and find that FSR is mostly dominated by FSRACC.

But someone said it is not reasonable. In their opinion (i kind agree), FSRACC is a means of protection, it only takes in charge when it is loss of control. So during normal startup, FSR should be determined by FSRSU, not FSRACC. FSRACC is protection not control.

So, CSA, what's your opinion?

It will be great help if your would like to respond.

Best regards!
Neo
 
Neo,

It would probably be better if you asked off-topic questions like this in new, separate threads. And, we are kind of getting off-topic with the discussion in this thread already (When will 88CR start?), and that's kind of the issue with the L4 threads--they got really off-track.

Anyway, in later versions of the Mark V, and in the Mark VI and the Mark VIe GE finally was able to use acceleration control during starting (after warm-up) to control the rate of acceleration. So, TNHAR (the acceleration rate reference) drive FSRACC during starting (after warm-up is complete) to make TNHA (the actual acceleration rate) equal to the reference. That's what they intended all along with the Mark IV, but it never worked very well, and also in the Mark V but early versions of the Mark V didn't handle acceleration during starting very well.

So, after firing and warm-up are complete, the unit should accelerate according to the acceleration rate reference.

This has caused a lot of problems though, because, quite frequently during warm-up the actual acceleration rate can exceed (sometimes greatly exceed) the acceleration rate reference--and when warm-up is complete then what happens is FSRACC drive FSR to minimum. And sometimes when that happens the flame can be completely lost OR flame is lost in one or more combustors leading to high exhaust temperature spreads during acceleration.

So, while they fixed the acceleration control during starting--they also have created some other issues with starting they didn't intend to create. And many commissioning TAs (field service personnel) don't understand what's happening and how to adjust minimum FSR to prevent this from happening--because there's not much one can do to limit acceleration during firing and warm-up (except when there is a torque adjustor mechanism which can sometimes be used to limit acceleration during warm-up).

Once the unit reaches rated speed (or thereabouts) then you are correct--FSRACC is set to limit a sudden acceleration (which would occur on loss of load (load rejection)). But, here again, if FSRMIN isn't set up correctly then loss of flame can (and quite often does) occur on load rejection.

Hope this helps!

I want to add something to the discussion about L1X--it's not just simply to drop out L1Z (which is the signal I believe you will find starts critical auxiliaries). It's also is the logic signal that basically indicates that a START is in progress and active, because, usually, it doesn't drop out until L2G times out (after the generator breaker closes).

Going forward, though, when the discussion drifts from the thread subject/topic we should really be starting new threads. The number of threads isn't a problem; but being off-topic can cause problems for others reading the threads later (those kind souls who use the 'Search' feature of control.com).
 
Neo,

I think it's best to think of it in this way: When the unit is not on speed control (specifically, droop speed control) at or near rated speed during starting (so when it's accelerating after firing and warm-up) that FSR is driven by FSRACC--until the unit reaches rated speed, at which time it goes on droop speed control (FSRN).

And, when the unit goes on droop speed control, then FSRACC becomes a "limit" trying to prevent a sudden acceleration due to loss of load.

Instead of having a special "start-up FSR" (say, FSRSU_ACC) GE is just using FSRACC to control acceleration rate during starting after firing/warm-up up to rated speed, at which time FSRN takes over and FSRACC becomes a limiter.
 
CSA:

Thank you so much for your point of view about FSR control during GT startup. We are more clear about it. Thanks, thanks so much.

At my site,the FSRMIN value at startup are listed below:<pre>
<b>TNHCOR FSRMIN
40% 14%
85% 11.9%</b></pre>
So, when warmup is complete, FSRMIN is 14%, and that means the minimum value of FSRACC is 14% too.

But i also find the warmup FSR is 11%. So,when when warmup is complete, if the actual acceleration rate is more than acceleration rate reference, the acceleration cannot be controlled. Because FSRSU is less than FSRACC at that moment. I think it is unreasonable, should FSRMIN be less than warmup FSR when warmup is complete?

"This has caused a lot of problems though, because, quite frequently during warm-up the actual acceleration rate can exceed (sometimes greatly exceed) the acceleration rate reference--and when warm-up is complete then what happens is FSRACC drive FSR to minimum And sometimes when that happens the flame can be completely lost OR flame is lost in one or more combustors leading to high exhaust temperature spreads during acceleration."

According to the application code at my site:<pre>
L2WZ L43O_F L4 L3 L83TAKSU
--------||------|/|------------||--------|/|-------( )
L2WX |
-----------------||------</pre>
L2WZ = Flame detector timer
L83TAKSU = select startup acceleration reference;

So, during the time from flame is detected to when startup is complete, L83TAKSU is logic 1.

So TNHAR is set to:<pre>
TNH TNHAR
40 0.11
50 0.11
75 0.31
95 0.31
100 0.1</pre>
<b>So, i think during warmup, the acceleration can be controlled by FSRACC is FSRMIN is set lower than warmup FSR.</b>

"Once the unit reaches rated speed (or thereabouts) then you are correct--FSRACC is set to limit a sudden acceleration (which would occur on loss of load (load rejection))."

When the unit reaches rated speed, L3 is logic 1, then L83TAKSU is logic 0. At that time TNHAR is set to TAKR1(1.0). So if now the unit is speed/load control, like FSRN=65%, FSRACC will be much larger than that value.<pre>
FSRACC=FSR+(TNHAR-TNHA)*FSRACC2
75= 65+(1-0)*10 <b>too large?</b></pre>
It seems that there has no chance that TNHAR=0.1 at TNH=100 can be used.

And i find that the startup acceleration rate is not exactly match the acceleration rate reference, especially during the 30%-50% TNH.

CSA, i think there are many errors in my understanding, if you would like to point out, i would be a great help.

Thanks in advance.

Best regards!
Neo
 
Neo,

Is the unit experiencing problems during start-up? High exhaust temperatures? High exhaust temperature spreads? Slow acceleration? Loss of flame trips?

I believe we are dealing with a GE-design Frame 6B heavy duty gas turbine, with an electric motor starter and a "fixed" torque converter (there are no variable guide vanes on the torque converter, and no solenoid-operated valve to increase/decrease oil flow/torque transmission). So, there is no way to limit acceleration once flame is established until the actual acceleration rate can be controlled by fuel flow. Sometimes that occurs at speeds around 40-50%; sometimes earlier, sometimes later.

It's not an exact science, this turbine control stuff. It's pretty good--and with the Mark VIe much better than before. But, it's not precise. If you believe that actual acceleration should be controlled at all times from firing to FSNL, that's just not reasonable. For most of the acceleration, it should be possible, but for low-speed acceleration--from warm-up to approximately 50% it just might not be, because the torque assist from the starting means through the torque converter may be more than is necessary to make actual equal to reference.

The only way to try to adjust that is by "playing with" FSRMIN and FSKSU_WU--but then you run the very real risk of high exhaust temperature spreads (because flame is lost in one or more combustors) and loss of flame (because flame is lost in a majority of the combustors with flame detectors).

The criteria for a "normal" start is:

--minimal exhaust temperature spike resulting from the establishment of flame [NOTE: There is a few seconds lag between the time flame is established and the time the exhaust temperature spikes--it's not exactly at the same time FSR is at FSKSU_FI.]

--low exhaust temperature spreads (indicating flame is present, and remains present, in all combustors during warm-up and acceleration

--controlled acceleration (via FSRACC) once the torque assist from the starting means begins to drop off

Some turbines, with adjustable torque converter guide vanes, have more of an ability to reduce or limit the torque assist so as to be able to control acceleration using FSRACC more closely shortly after warm-up and during most of the acceleration. <b>BUT,</b> sometimes it's just not very possible to get on acceleration control much below approximately 45% speed <i>even on those machines</i> without losing flame in one or more combustors. AND, while you may get it to be very reliable at one ambient temperature, another ambient and slight changes in fuel heat content can greatly affect reliability at other times of the year (or even as fuel changes--which it does, sometimes more than others (liquid fuel seems to vary more often than natural gas fuel, but if the gas fuel is from an LNG source, that, too, can vary greatly)).

This is the "black art" part of gas turbine operation and control. One has to understand what abilities, auxiliaries and equipments each turbine has and then what is possible and what is not possible.

One thing which must be remembered about GE-design heavy duty gas turbines is that for the most part the equipment design hasn't changed much for decades. By that I mean, auxiliaries and components. Sure, they might use different vendors for solenoids or fuel control valves, or use DLN combustors, but the starting means and other similar systems haven't changed all that much--even though the control systems have advanced greatly! So, while the ability of the control systems have greatly improved (by orders of magnitude), the equipment hasn't advanced nearly as much (the auxiliaries, specifically--like the torque converter, for example).

There's always the issue of maintaining flame during acceleration to limit exhaust temperature spikes, spreads and loss of flame trips. Remember, also, that the turbines need a torque assist from the starting means during firing, warm-up and initial acceleration--they just can't develop sufficient torque to accelerate themselves simply from the expansion of hot gases through the turbine section at low speeds. Heavy duty axial compressors are VERY heavy, and so is the generator rotor. (Many people complain that aircraft derivative engines don't require a torque assist--and they are "gas turbine engines." But they are MUCH lighter in just about every way--and they are multi-shaft machines and the axial compressor is shorter and lighter and the gas generator shaft doesn't have to drive a load during firing and initial acceleration. They are very different beasts.)

The <i><b>intent</i></b> of acceleration control is to control the rate of acceleration during starting with fuel--but that's just not possible while maintaining flame with the current auxiliaries. If you had experience with Mark IVs and early Mark Vs, you would know that acceleration control wasn't--the acceleration was not controlled at all. It just was what it was--even though the Control Specification described acceleration control. The software and the hardware (the microprocessor) just weren't up to the task. So, what's available now is a huge improvement--and much better for the machine.

As for FSRACC at rated speed, well, look at the FSR Display on the HMI. You will see that it very closely tracks FSR (FSRN at part load) and I've never really had a reason to question it or have it be a problem, so without being able to see the application code in your Mark VIe I can't really say for sure exactly what's happening.

Again, this thread is getting pretty far afield of the original topic. And, you are "splitting hairs" (which are very fine and very difficult to split!) with your interpretation of how tightly the Mark VIe should be able to control acceleration. Sure; with more variability in the torque converter it might be possible to have very exact control--but at what cost? And, there's always the consideration of maintaining flame in all the combustors during low-speed operation and acceleration. Sometimes, you just have to put admit a little more fuel in order to keep the flame from being blown out. And the converse of that is trying to limit the exhaust temperature spike--not only during light-off, but also during acceleration. It's a pretty good balancing act--that was much more difficult with older control systems.

Is your machine not working correctly because it can't control acceleration at all speeds above warm-up? Absolutely not. Do you have high spreads? Or high exhaust temperatures? Or loss of flame trips during acceleration? Then, in that case, something should be done--but there are limits to what can be done and it's not very reasonable to assume that acceleration control is going to be functional from warm-up to FSNL.

If we're all done with 88CR, new questions should have their own threads.
 
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