hi every one
we have GE gas turbine frame 5 ..my inquiry that we have oscilation in Vce voltage we need to find causes but we check every think not found the causes please any one who can to give his suggestion or any opinion I waiting that ....

 

Do you think that if you keep opening new threads that it will get you more answers than your first grossly inadequate posting?

Other problems with Mark II control systems included power supply issues; if those power supplies were properly maintained or got hot under load, they were known to be a little temperamental and flaky.

I've also seen the pins and wiring of the back-planes of the card page of the Mark II be pretty poorly maintained, including lots of dust and dirt and cobwebs, which, in a humid environment is bad news.

You also haven't told us if you have a Mark II or a Mark II w/ITS (Integrated Temperature Sensor).

You haven't told us if the SRV is oscillating or the GCV is oscillating. You haven't told us how much the VCE is oscillating. You haven't told us if the gas fuel supply pressure is stable or oscillates at the same frequency as the oscillations of the load.

When the unit is running at Part Load (not on Pre-Selected Load Control, if this option is present), the reference is speed and the feedback is speed. So, have you verified that the speed pick-ups are good at rated speed? If the unit has Pre-Selected Load Control and it's being used at Part Load, have you verified that the load transducer feedback is working properly?

Think about it.

You've eliminated the control system components from the list of possible problems (at least the components you've described).

What does that leave? The electro-hydraulic servo-valve. The hydraulic actuator. LVDT feedback. P2 pressure transducer feedback. Oil cleanliness (how long has it been since the last oil change or the last oil sample was taken and sent for analysis?).

Troubleshooting is a process of elimination. Sometimes is a big job, but if you approach it logically and make a list of all the possible problems, and start working down the path you deem most likely, if you get to the end of that path and you still haven't solved the problem, then you go back to the beginning of the list and start working down another path, until you've solved the problem or eliminated everything you can think of.

And, then when you ask for help, it's helpful to tell the person or people what you've done to try to troubleshoot the problem and be prepared to provide the results of the testing and troubleshooting. You need to tell the person or people you are asking for help when the problem began (after a maintenance outage? suddenly? after a gas compressor outage?). You need to tell us how you are operating the unit (Part Load under manual control (operator just manually raising and lowering the load), or Pre-Selected Load Control (entering a Load Setpoint and letting the control system adjust the turbine speed reference to control load to match the setpoint), or if there's some other method of load control/loading that's being employed.

My personal bet is that the speed pick-ups are working intermittently, or there's an oil cleanliness problem, or there's a problem with the P2 pressure transducer, or there's an LVDT feedback problem on either the SRV or the GCV, or there's a Mark II power supply problem (not really likely, but a possibility).

But, one thing's for certain: You haven't given us much information and it doesn't seem like you've considered all the possible issues.

 

Thank you for given you opinion about that. but I tall you this problem still present and gas turbine at working with load because of the usual of company so.

I tell you the information that you need:
the type of gas turbine is frame 5 markII.
we see this swing when a turbine at complete sequence (before & after loading). So we check the cards: SSKC, STKK, SHPB, SSZB, SVSE, GCV-SRV CARD but not any response. Two valves GCV&SRV are oscilatione with same of VCE voltage between (8-11) volt that is approximately 3 degree.

The supply pressure of gas fuel is oscilation too. We replace the speed pick up & load tranceducer feedback but not get any result. We suspect in servovalve and replace it also - same result.

LVDT &P2 pressure tranceducer are new devices.

Are you think may be in oil cleanliness. It's a thing alone that we did not analyze.

in the end I written a new thread because dont found any answer. I like to tell you I'm electrical engineer working on control turbine panale speedtronic. Now Im go to development this speedtronic mark II to mark VIe GE gas turbine

After all that thanks to you from my heart

 

I think you have just revealed a telling bit of information, the fact that your gas supply pressure is swinging. Of course it could be possible that the SRV/GCV swing is impacting back on the supply pressure but I would try and get rid of the supply pressure swing first. Do realise, if you are not too familiar with your system, that any supply pressure swing will immediately reflect completely through your gas fuel control system causing VCE to swing around.

 

hi Bob..
I thank you to your opinion...
but I need to tell you the swing in Vce not in gas supply pressure as you write..


thanks alot

best regard

 

Bob Johnston,

I think we've tried hard enough.

I guess he was mistaken when he said:

>> The supply pressure of gas fuel is oscilation too.

I'm done with this. Getting any information is like trying to get blood from a turnip. Now, the veracity of that information is subject, also. I'm not sure we can trust anything that's been said or done to troubleshoot this problem.

 

Bob & CSA

Thanks a lot about this notes but not in my intent to tried you a hard enough but I'm for the purpose of to show the case...believe me.

Yes, I write this sentence but I think this is a result not a cause in other words I don't want to hurt your feeling. I'm very sorry about that.

Important Note:

I think when you ask me about gas supply pressure I think the gas enter after gas control valve, I'm sorry again.

 

Did you solve this? I know it's 3 years ago.