Dear All

from few days we have observed hunting in IGV, machine remain about 95% on TETC but some time it goes to LOAD controller when gas pressure is not sufficient. can you plz share your experience what could be the reason behind this? while our machine is GT V94.2 Siemens make ANSALDO and actuator from AUMA.

ashiq

 

> from few days we have observed hunting in IGV, machine remain about 95% on TETC
> but some time it goes to LOAD controller when gas pressure is not sufficient.

---- snip ----

can any one pls share the possible causes of hunting

 

ashiq,

We don't get too many Siemens-related posts here on control.com. I think most are unfamiliar with the terms used in Siemens control systems, and possibly with the types of actuators and the inputs to the references and feedbacks from the IGVs that might be causing problems with the unit at your site.

Also, you haven't provided enough information for us to be of much help. For example, when does this hunting occur? During the 95% of the time the unit is on TETC, or during the time when it's LOAD control, or during the time when the gas fuel pressure is low? You just haven't provided enough information.

You need to examine the control system logic and configuration at your site to understand what could be causing the reference to the IGV actuator to fluctuate, if it is fluctuating, or if the feedback is unstable, or if the actuator is unstable.

Troubleshooting is sometimes (more often then not, actually!) a process of elimination. You make your best guess at what the problem might be and then you test your hypothesis and if you're wrong then you move on to another possible cause until you find the reason(s). In the process, you usually learn at least a little something about components or control schemes that will be helpful in the future and will usually help you make better-educated guesses when tackling an unknown problem in the future.

Write back to let us know what you find, and could you please explain "TETC" for those of us not familiar with Siemens control schemes and terminology? (Does it stand for Turbine Exhaust Temperature Control?)

 

Dear CSA

i will follow your instruction during troubleshooting..
yes your are right TETC in GT Siemens v 94.2 stands for Turbine Exhaust Temperature control.
while this machine have following controllers

Startup
Speed
Load
TETC
Load Limit

cheers
Ashiq

 

which control system your plant has? T3000, OR T2000, WHEN IGV HUNTS, DOES IT GIVE ALARM IGV LIMIT SWITCH OPEN LEFT", It may because of tracking error between two controllers in case of T 3000 control system.

 

Infi-90 is the control system at our plant...while this issue was fixed automatically when we replaced the control assembly/unit of auma control valve actuator ...that control assembly went in fault due to EEPROM failure.

i think hunting was originating from control unit assembly.

now it is working very well

thanks to all of friends

best regards
ashiq

 

ashiq,

Thanks for the update and feedback!

 

>Thanks for the update and feedback!

when your load demand and actual load is different, this hunting will be happen so before decrees load. plz set load equal to actual load