Mr Rajesh,

I am afraid CSA wont be answering your queries anymore

http://www.control.com/thread/1324829561

 

Yes Mr.freelaneng, Mr.CSA have started new career. But still we can expect other experts feedback.

We are currently studying more on the issue and update you soon.

Take care
G.Rajesh

 

CSA was a great contributor to the Control.com board and the community will miss him greatly. I wish him the best of luck with his future.

Just a quick note for those seeking support on controls operating GE turbines or GE Mark controls operating non-GE turbines. You can receive free support at GE's Controls Connect internet portal.

If you are a turbine operator Controls Connect gives you access to our knowledge database which has an advanced search engine for finding knowledge articles, manuals, application guides, TILs, white papers, etc. We also provide phone/email support from our technical support team. This is all a free service.

CONTROLS CONNECT NOTE: If you have a GE SSO#/Login and are a GE turbine operator, business associate or EPC firm, please send an email with the subject "Controls Connect Access" and include your SSO#, Name and Company. Note that GE can not accept generic email addresses (e.g. @yahoo, @hotmail, @gmail, etc). Company based email addresses are required for security reasons. Your registration will take approximately 3 days. If you do not have a GE SSO#/Login you can register at http://site.ge-energy.com/online_tools/controls_connect.htm or just perform a Google search on "Controls Connect". Just click on the register button to start the process. Registration forms should require less than 5 minutes to complete. If you have any questions feel free to contact me at [email protected]

I am the Product Line Leader at GE Measurement and Controls.

 

Dear G.Rajesh

> 0% = 0.825 Vrms, IGV angle in HMI screen is 35.1 DGA (Hydraulic pump is not running)
> 0% = 0.775 Vrms, IGV angle in HMI screen is 34.1 DGA (Hydraulic pump is running).

As CSA said...something is very wrong....

Personally, I suggest that you should go check the bolts on the hydraulic pneumatic's base box, they may loose.

good luck

 

Dear Ray

Thank you for your feedback.

Now unit is running we will examine when it's down and back to you with feedback.

Thank you
Take care
G.Rajesh

 

Dear All,

We have inspected our IGV during the past maintenance and observed closed angle is only 28 deg and full open is 84 deg. We have done auto calibration and checked again with Speedtronic against real IGV position and confirmed both are matching exactly.

After this calibration, we have started the unit and observed exhaust temperature and CPD are matching with the another unit (earlier ex. temp is 10 deg.C more & CPD 0.5 bar less compare with other unit).

Now base load is limited at ex. temp 530 deg.C (load: 104 MW, CPD is 10.5 bar, Amb. temp 30 deg.C). In the past ex.temp 552 deg.C at base load (load 103 MW, CPD 9.97 bar, Amb. temp 33 deg.C). This issue we shall discuss in the new thread.

Thank you CSA & all for your supports.

Take care
G.Rajesh
Thank you

 

Dear All,

If anybody having a thought, why IGV angle moved to 28 deg.c, please share with us.


Take care
G.Rajesh
Thank you

 

G.Rajesh,

You would need to look at the drawings (mechanical drawings) for the LVDT actuator and guide ring to understand how the mechanical stops are set and could be adjusted. The stops are different for different types of actuators and machines. But the stops are usually adjustable (meaning they can be moved or changed by changing shim thickness or some other method), and are supposed to be checked and adjusted if necessary when work is performed on the IGV actuator or guide ring by the mechanical crew performing the work. And the stops are to be adjusted/set to values usually specified in the Control Specification, and usually mirrored on the mechanical drawings (though if different, the Control Specification values should win).

The minimum operating angle for many non-F-class GE-design heavy duty gas turbines is 34 degrees (angle, not C). So, during starting and shutdown, when the IGV position is being controlled the Speedtronic will move the IGVs to the indicated angle (from the calibrated LVDT feedback) of 34 DGA (DeGrees Angle).

If the mechanical stop is actually 84 DGA, that's kind of not very good, because the maximum operating angle for many non-F-class GE-design heavy duty gas turbines is 84 DGA. So, that would mean the IGVs are being operated at a mechanical stop, and that is not what's intended at all. Per the Control Specification, the actuator stops are usually to be set to 2 DGA beyond the minimum- and maximum operating angles; those are typical values, not hard-and-fast values.

If the measured IGV angles are 28 DGA and 84 DGA at the mechanical stops, then the mechanical stops seem to have been adjusted/set to 28 DGA and 84 DGA.

The Mark doesn't adjust or set mechanical stops. It doesn't even know what the mechanical stops are or should be--unless "told" (read on). Someone has to physically measure the IGVs at the minimum and mechanical stops, and, if using AutoCalibrate, put those values into the appropriate fields in AUTOCAL.DAT for AutoCalibrate to use in calibrating IGV feedback. But, the Mark only knows what it's told in AUTOCAL.DAT, which should be the measured angles at the stops.

So, how do you think the minimum and maximum angles got to be 28 DGA and 84 DGA?

It's interesting to note that the travel from 28 to 84 DGA is 56 degrees, and that the travel from 30 to 86 DGA is also 56 degrees. And 30 and 86 DGA would be much closer to the typical values for stop settings of approximately 32 and 86 DGA than 28 and 84.

Just noting. I really wonder if the physical measurements of IGV angles were all that accurate.

 

Dear CSA,

Thank you for your feedback.

We have measured many times and confirmed it values (at differnent blades). Moreover after this auto calibration only our exhasut temperature and CPD were matching with the other unit (earlier 10 deg.C more and 0.5 bar less).

The above problem might be started after our major inspection which was done on 2010.

So in the next outage, we are planning to move the IGV from 28 to 32 since you know well, if IGV at 28 we won't get permissive to start.

We agreed with you, if 28 deg moved to 32 deg the maximum stop would be 88 deg as per our measurement (since present is 84 deg). we'll inform you once it measured.

Thank you very much for your endless supports.

Take care
G.Rajesh

 

Hi Guys,

I have a doubt in IGV calibration.
Our unit was not going above 25mw since it is going in temperature control mode.
During shutdown when we gave stroke check in manual mode which is mark v. Found during 100% stroke check it was opening only 60dga even when we did autocalibrate still the same. We even installed new LVDT it is still the same.
Can you please help me out how to calibrate IGV step by step in MARK V.

 

sandeep03pradeep,

You didn't say what Frame size GE-design heavy duty gas turbine you are working on.

WHEN did this problem start? After a trip from load? After a maintenance outage?

Can you describe the basic steps involved in installing the new LVDT (and if the unit only has a single LVDT on the IGVs, or dual redundant LVDTs, did you replace both of them--and how (basically))?

Are you actually measuring the IGV angle when using AutoCalibrate to stroke the IGVs? Or are you relying on the calibration (scaling) of the IGV LVDT feedback to be accurate?

If you are "measuring" the IGV angle and comparing it to the reference value used in AutoCalibrate are you using the pointer on the outside of the axial compressor casing, or are you physically having some enter the inlet duct and use a machinist's protractor to measure the actual IGV angle?

If you're having someone enter the inlet duct and using a machinist's protractor to measure the actual IGV angle are you having that person physically verify that all the IGVs have the same amount of "play" and some aren't looser than others (have more "play", or slop)?

If, in fact, the IGVs are NOT moving to an opening greater than approximately 60 DGA, then it's very likely the problem is mechanical and NOT controls-related. In this case, using AutoCalibrate won't solve the problem of the IGVs failing to open to the open mechanical limit.

Does the Mark V use an <I> operator interface (running an older proprietary operating system called IDOS, usually with somewhat crude graphic displays), or a GE Mark V HMI running some version of MS-Windows and CIMPLICITY and a proprietary background MS-Windows service called TCI)?

When you are "stroking" the IGVs, are you using AutoCalibrate, or the User-Defined (Demand) Display for manually stroking the IGVs?

Finally, the topic of using AutoCalibrate has been covered MANY times before on control.com, though to be honest I don't know how often the topic of IGV LVDT feedback calibration has been covered or in how much detail. But, before we get too far along in this process, let's first understand what Frame size machine you are working on, how you are measuring/verifying the actual IGV angle/position, and how you are stroking the IGVs. We can use that information to help you understand how to proceed, and if that means re-calibrating the IGV LVDT feedback.

 

Hmmm....

Just a few quick answers was all that was asked for:

1) Frame size of machine with problem?
2) When did the problem start?
3) Describe the basic steps when the LVDT was replaced
4) How do you know the IGVs are only at 60-some DGA?

Not much to ask. Shouldn't take too long, even if you want to skip the third question.

Again, if you're physically measuring the IGV angle and it's only going to 60-some DGA when you put in a reference of 100, then it's probably NOT the Mark V--it's something outside the Mark V. Could be the servo; could be the hydraulic actuator. I've seen the bolts that hold the hydraulic actuator to the I-beam be broken and bent and the bolt holes so worn and elongated that even though the actuator stroked from end to end (stop to stop) the IGV ring wouldn't move through the entire range of travel (this was on a Frame 6, with the IGV actuator under the inlet plenum floor, and no one was looking at the actuator--it was just assumed it was good...).

But, some kind of status would be nice. If you've solved the problem, or found the cause of the problem and are working on a resolution--it would be nice to know.

 

Hi,

Sorry for the late reply.
Frame size- 6B
It was found that the actuator was the problem and when we changed the actuator and gave auto-calibration it was opening fully.
We found out the fault by removing the LVDT and gave a command for 80DGA then also it was opening only 60DGA. Then we replaced the new actuator and gave command for 80DGA it was working fine. Thanks for your support

Thank You

 

Thank you for the feedback!

"The most important contribution at control.com is feedback!"(TM) Everyone reading these posts--now and later--benefits from the information provided and probably even more from the feedback. So, thank you!

 

Dear CSA,
Can we start gas turbine after selecting "ISO" speed control mode?

 

@MSFK,

CSA is no longer contributing to Control.com, but in his absence I would be happy to respond to a separate thread devoted to this topic. (Your question has nothing to do with IGV calibration (if I understand the question correctly).)

You should be easily able to find the 'Post New Thread' by clicking on 'Forums' on the Menu bar of any Control.com webpage, and then click on 'Latest' and you should be presented with the 'Post New Thread' button as shown in the snippet below:




Don't worry about which Forum to post the thread in, though 'Power Generation' would be the most appropriate.

Please tell us a little about the machine you are asking about--manufacturer, control system, why are you selecting Isochronous Speed Control--and is it the normal mode of operation/start-up for your site. Is the plant a "captive" power plant--meaning that is can supply a nearby plant/load(s) independent of a large utility/grid? The more information you can provide the faster and more concise the response(s) will be.