Before asking any questions I want to explain something about the circumstances of one of our GT. GT (Frame 6B) tripped showing following alarms:

1. Excitation overcurrent -1st step at 18:10:34.229
2. Loss of Flame at 18:10:34.589

It is really confusing that for excitation overcurrent GT should not trip it should go to FSNL.

In trip log of GT it was found that at 18:10:33 FPG2 reduced from 19.27 bar to 15.27 bar and at 18:10:34 FPG2 went to 6.25 bar and mean while SRV opening was going down because of servo current in trip log was going down from -26.5% to +72%.

Then we replaced the existing servo of SRV and calibrated it. After calibration we got the following message:

R STATUS: State=116, (0x74)
S STATUS: State=116, (0x74)
T STATUS: State=116, (0x74)

We tried several times to get "Calibration Finished" message but we failed. I didn't know why the above message came???

Another problem we found during runtime of GT:
..........................<R>.......<S>........<T>
Required Position...17.39....17.39......17.39..%
Actual Position......18.31....18.30......18.32 %
Servo Current.......49.69....-27.23.....-26.55 %

Why the servo current of R core is so different than the other two?

It should be mentioned that we have Frame 6B GT and Mark V control system.

 

You have not provided sufficient information to tell us why the unit might have tripped.

From the information provided, it would appear that one of the servo coils has the wrong polarity of applied current, and the other two coils are trying to compensate.

I'm not familiar with the alarm messages from the attempted AutoCalibration.

I will say this: It's never necessary to (re-)calibrate LVDT feedback when you replace a servo if that's the only change being made. Changing the servo does <b>NOTHING</b> to change the stroke of the device, which is all that the LVDTs measure: physical stroke of the device to which they are attached.

And, LVDTs should <b>NEVER</b> be calibrated <b>UNLESS</b> it is known that the feedback does not match the physical position (stroke) of the device. Meaning that before performing (re-)calibration of LVDT feedback one should check the calibration to see if it needs calibration.

Full stop. Period. End of discussion.

 

It does appear that the park position of the sensor may have moved it is necessary to move the sensor through its full range to find the zero position, then set your servo zero, then calibrate through the full span...