Good Day,

I am looking for some advice on the above captioned. We got an IGV control trouble alarm on the Unit. The IGV supposed to be 57 deg at FSNL however the angle was at 44 deg. This was verified on the field. The servo current is -50.36 on R; -51.09 on S; -51.78 on T. Can someone help me on this issue? I would appreciate.

 

What other Process Alarms and Diagnostic Alarms are active (all of them, please)?

Do you have anything forced?

Did you have to force anything to start the unit?

What combustion system does the turbine have: Conventional (Diffusion flame) or DLN-I?

Does the unit have IBH (Inlet Bleed Heat)?

What turbine control system is used on the turbine?

 

It appears that the control system is a GE Mark series. The RST description denotes that assumption.

Servo current is nice to have: however LVDT feedback is the real answer.

The MK* servos have COMMANDED the IGV to 57 degrees, yet the LVDTs are giving a FEEDBACK of 44 degrees.

The FEEDBACK from the LVDT was confirmed in the field as accurate.

This is the source of your IGV control trouble alarm .

I recommended that the IGV be calibrated and verified. This could be mechanical problem or a servo problem.

Very little information other than HELP ME.

Provide me with more information and perhaps I CAN HELP YOU.

WTFCSA

 

Curious _One,

You are correct. It’s probably a Mark* turbine control system. After all, it IS a Frame 7 (E, or EA, or F, or FA, or H, or HA).

But—if the calibrated LVDT feedback says 44 DGA and the field verification also says 44 DGA, doesn’t that suggest the LVDT feedback is (still) calibrated? WTF is calibrating the IGVs going to do to to solve the problem if the IGV hydraulic actuator can’t physically move the IGVs to the commanded position? (AND —what if the IGV actuator is electric and not hydraulic??? Aren’t all GE Frame 7 IGV actuators the same? After all, we are talking about a GE Frame 7.)

You are also correct: Knowing the servo currents was nice. Other than the calibrated LVDT feedback being verified “on the field” there’s nothing else of value in the entire post (including the subject).

Calibrate away!