Turbine Ge frame 5 can't end startup sequence

Hi

during start up of GE frame 5 ms 5002B, the start up sequence stop at 84% hp speed and can't reach 95% to stop bleed valves and auxiliaries of start up. we noticed that FSR value taking start up value which is the min selection value rather than acceleration value which was min and used during warm up. when the acceleration value become greater than the start up value by 0.2 which is sufficient to make the turbine reach 95% . This problem is showen after major inspection of the turbine . I tried to adjust FSKSUAR value from 31.7 to 36.7 this allowed me to start the turbine but affter a shutdown and restart of the probelem is still exist
 
Taki27,

What turbine control system is being used to control and protect the turbine?

What fuel is being used after the shutdown? (Is it the same fuel as before the shutdown?)

If it is gas fuel, did someone "calibrate" the gas fuel valves before, during or after the outage?

Were the fuel valves worked on or replaced during the outage? If so, what was done?

What is the value of actual exhaust temperature when the unit reaches 85% speed? (The signal name for most GE turbine control systems is TTXM.)

What is the value of the maximum allowable exhaust temperature when the unit reaches 85% speed? (The signal name for most GE turbine control systems is TTRX.)

What are the exhaust temperature spreads when the unit reaches 85% speed? (The signal names for most GE turbine control systems is TTXSP1, and possibly TTXSP2 and TTXSP3.)

Was the starting means worked or replaced during the shutdown (including the prime mover (an electric motor, or a diesel engine, and/or the torque converter)? If so, what was done to the starting means?

Were the turbine and/or load gear and/or generator beatings replaced. I'm presuming the unit is a generator drive; if it's a mechanical drive powering a centrifugal compressor is the load of the compressor any different (greater than) after the outage than before the outage?

If the unit has variable second stage nozzles, is the mechanism working correctly? Are the LVDTs calibrated correctly?

If the turbine control system is a GE make/model and if it is digital control system, it is very possible that the acceleration rate after the shutdown is excessive (THNA is greater than TNHAR) possibly because of something that was done to the starting means or to the fuel control valve(s) (including "calibration" of LVDTs). AND/OR it could be that after the shutdown the exhaust temperature spreads are very high which is negatively affecting the actual exhaust temperature value (TTXM) and causing it to be higher than normal which is preventing the turbine control system from allowing any more fuel to flow to the turbine which is preventing acceleration.

Those are the usual problems; but without more information and data there's not too much more we can add. If you require further assistance, please answer ALL of the questions asked above (not just the ones you deem relevant!).

Please write back to let us know how you succeed in resolving the problem(s).
 
The control system is Mark V
The fuel is naturel gas
The spread is about 34 °
I did calibration of the SRV & GCV ; IGV and nozzle.
I verified everything the SRV ;GCV NOZZLE IGV .
THEY CHANGE FUEL NOZZLE DURING THE OUTAGE
I verified also that there is no hot gas leakage .
But the problem still exist .
I changed the constant FSKSUAR we reach to end startup sequence successfully
But after trip of the turbine because of a problem in process.
The problem reappear and the turbine can't end the startup sequence
 
Do you have the before and after LVDT calibration values (0%- and 100% values for all LVDTS--BEFORE and AFTER calibration)?

You say, now, they replaced the fuel nozzles.... What was the source of the fuel nozzles? Were they refurbished nozzles? New nozzles? Were they sent out and refurbished? Do you have the flow measurements for the new nozzles, AND the flow measurements for the old nozzles? Is it possible the new nozzles don't flow as much fuel as the old nozzles? It could be that the unit is "starving" for fuel?

AND, you DID NOT provide the TTXM and TTRX information requested, nor did you pick up on the hint about THNA and TNHAR.

Nothing about the driven equipment (generator, or centrifugal compressor). Nothing about the LP shaft speed.

Changing Control Constants is a dangerous thing unless you know ALL the knock-on effects. Especially during starting--because of the way GE mixed start-up/shutdown parameters. AND, 36.7% for FSKSUAR is high, very high. One has to wonder what FSKSU_FI and FSKSU_WU are....

Troubleshooting is often a process of elimination. And, based on the information provided it's just not possible for someone to say, "Oh, yeah! I've seen that exact problem before and it's caused by [this] or [that]!"

I don't recall off the top of my head what the "FSNL" HP speed is for a MS-5002B machine, but I think 85% is pretty close (right?). Either the Mark* is limiting fuel because the exhaust temperature is too hot (TTXM>TTRX), or the acceleration rate is too high (TNHA>TNHAR), or there simply isn't enough fuel getting into the machine to get that few extra percent of HP speed.
(Increasing FSKSUAR could have caused TTXM--when the machine was hot after the trip--to exceed TTRX.... I've seen it happen before, but you didn't give us any idea of what the temperatures were.)

Look, I know I'm asking for a lot of data you probably don't have access to. Use VIEW2, or one of the VIEW tools, and record the values during a START. If you need a list of values, I can provide that. If you need the command line command with switches, I can provide that. But, I can't do anything more without better, actionable data (actual time-based values, including speeds).
 
Do you have the before and after LVDT calibration values (0%- and 100% values for all LVDTS--BEFORE and AFTER calibration)?

You say, now, they replaced the fuel nozzles.... What was the source of the fuel nozzles? Were they refurbished nozzles? New nozzles? Were they sent out and refurbished? Do you have the flow measurements for the new nozzles, AND the flow measurements for the old nozzles? Is it possible the new nozzles don't flow as much fuel as the old nozzles? It could be that the unit is "starving" for fuel?

AND, you DID NOT provide the TTXM and TTRX information requested, nor did you pick up on the hint about THNA and TNHAR.

Nothing about the driven equipment (generator, or centrifugal compressor). Nothing about the LP shaft speed.

Changing Control Constants is a dangerous thing unless you know ALL the knock-on effects. Especially during starting--because of the way GE mixed start-up/shutdown parameters. AND, 36.7% for FSKSUAR is high, very high. One has to wonder what FSKSU_FI and FSKSU_WU are....

Troubleshooting is often a process of elimination. And, based on the information provided it's just not possible for someone to say, "Oh, yeah! I've seen that exact problem before and it's caused by [this] or [that]!"

I don't recall off the top of my head what the "FSNL" HP speed is for a MS-5002B machine, but I think 85% is pretty close (right?). Either the Mark* is limiting fuel because the exhaust temperature is too hot (TTXM>TTRX), or the acceleration rate is too high (TNHA>TNHAR), or there simply isn't enough fuel getting into the machine to get that few extra percent of HP speed.
(Increasing FSKSUAR could have caused TTXM--when the machine was hot after the trip--to exceed TTRX.... I've seen it happen before, but you didn't give us any idea of what the temperatures were.)

Look, I know I'm asking for a lot of data you probably don't have access to. Use VIEW2, or one of the VIEW tools, and record the values during a START. If you need a list of values, I can provide that. If you need the command line command with switches, I can provide that. But, I can't do anything more without better, actionable data (actual time-based values, including speeds).
Can you give me your mail and i will send you the screen shots
 
Taki27,

I would really need to see the CSP running in the Mark V to see what's happening. I see TTXM is less than TTRX, so that's not the problem.

You said you calibrated SRV- and GCV- and IGV LVDTs; what about the 2nd Stage Nozzle LVDTs?

I can't recall if acceleration control is used for the HP shaft or the LP shaft, or both, but I don't see any values on any of the displays for either of those.

As I recall fuel control is for LP shaft speed, and nozzle control is for HP shaft speed. (Yes, there is some interaction between them, but that's how the control systems use to be designed for two-shaft machines.)

So, is the LP shaft speed higher or lower than it usually is at 85% TNH???

The FSR display is showing FSRSU is in control (the green bargraph). And, it's about 4% higher than FSRSU.

I don't understand the MESSAGE about 'PRCS xxxx Inh'. And in the middle of looking at the screenshots, they just disappeared...

I also noted the dates on the screens: 21 Mar 2021.?.?.?

Anyway, if the only thing that's changed is the fuel nozzles, are you CERTAIN the nozzles are the same size as what was replaced?

Are you sure the y-strainer upstream of the SRV is not plugged (choked)?

I didn't get to see P2 pressures.... before the screenshots disappeared.

It sure seems like there isn't enough fuel getting to the unit--it would be EXCELLENT if you had some FSRs from a good start to compare against.
 
Taki27,

I would really need to see the CSP running in the Mark V to see what's happening. I see TTXM is less than TTRX, so that's not the problem.

You said you calibrated SRV- and GCV- and IGV LVDTs; what about the 2nd Stage Nozzle LVDTs?

I can't recall if acceleration control is used for the HP shaft or the LP shaft, or both, but I don't see any values on any of the displays for either of those.

As I recall fuel control is for LP shaft speed, and nozzle control is for HP shaft speed. (Yes, there is some interaction between them, but that's how the control systems use to be designed for two-shaft machines.)

So, is the LP shaft speed higher or lower than it usually is at 85% TNH???

The FSR display is showing FSRSU is in control (the green bargraph). And, it's about 4% higher than FSRSU.

I don't understand the MESSAGE about 'PRCS xxxx Inh'. And in the middle of looking at the screenshots, they just disappeared...

I also noted the dates on the screens: 21 Mar 2021.?.?.?

Anyway, if the only thing that's changed is the fuel nozzles, are you CERTAIN the nozzles are the same size as what was replaced?

Are you sure the y-strainer upstream of the SRV is not plugged (choked)?

I didn't get to see P2 pressures.... before the screenshots disappeared.

It sure seems like there isn't enough fuel getting to the unit--it would be EXCELLENT if you had some FSRs from a good start to compare against.
 
Taki27,

I would really need to see the CSP running in the Mark V to see what's happening. I see TTXM is less than TTRX, so that's not the problem.

You said you calibrated SRV- and GCV- and IGV LVDTs; what about the 2nd Stage Nozzle LVDTs?

I can't recall if acceleration control is used for the HP shaft or the LP shaft, or both, but I don't see any values on any of the displays for either of those.

As I recall fuel control is for LP shaft speed, and nozzle control is for HP shaft speed. (Yes, there is some interaction between them, but that's how the control systems use to be designed for two-shaft machines.)

So, is the LP shaft speed higher or lower than it usually is at 85% TNH???

The FSR display is showing FSRSU is in control (the green bargraph). And, it's about 4% higher than FSRSU.

I don't understand the MESSAGE about 'PRCS xxxx Inh'. And in the middle of looking at the screenshots, they just disappeared...

I also noted the dates on the screens: 21 Mar 2021.?.?.?

Anyway, if the only thing that's changed is the fuel nozzles, are you CERTAIN the nozzles are the same size as what was replaced?

Are you sure the y-strainer upstream of the SRV is not plugged (choked)?

I didn't get to see P2 pressures.... before the screenshots disappeared.

It sure seems like there isn't enough fuel getting to the unit--it would be EXCELLENT if you had some FSRs from a good start to compare against.
CSA
I have reread your post and one question come to my mind:
You stated that :"As I recall fuel control is for LP shaft speed, and nozzle control is for HP shaft speed" Would you mean that Fuel control is for HP (not LP ) shaft speed and Nozzle control is for LP (Not HP) shaft speed...

Thx for clarifying
James
 
ControlsGuy25,

No; fuel control is for LP--because the LP drives the load (the centrifugal compressor). Nozzle control is for HP. The HP is the hot gas generator for the LP (personally I think of it as the "secondary" shaft and control once the LP is in it's operating speed range). There is some interaction in that when fuel is increased HP shaft speed will also increase slightly at the same time as LP shaft speed, but the load is driven by the LP shaft and the nozzle control will throttle back on the HP shaft speed to send more energy to the LP shaft. It's slightly counter-intuitive, but if you think it through it becomes clear. It's a big balancing act to keep the HP running in it's optimum speed range while producing power with the LP at the same time.

I don't recall at what speed for a two-shaft machine the IGVs will begin to open, but on a single shaft machine I think it's around 78-82% HP shaft speed, and they are ramped open. I just don't recall when that starts on two-shaft machines.

I suspect the original poster was forced to remove the screenshots, probably because they contained the site name. And, he hasn't written back since the screenshot files were deleted. So, I don't think we're going to get much more from the original poster--unfortunately.

I also suspect the problem has been found and resolved. And, we may also never know what it was.

Them's the breaks in this business.
 
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