Dear all
in our frame 6 units there are two type if lvdt according to spare part manual ( 311A5178P002 and 311A5782P002) is there any difference between both? The problem is the IGV open full to final mechanical stop, even when i calibrate the close position 32° to 0.689 Vac.
We use DOS IDP software
Usually the differences in GE LVDT part numbers are related to things like effective stroke (length of linear output), size, lead length, bolt pattern, etc. To answer your implied question, you probably can't interchange the two LVDTs simply and easily. Only you can see and know what the two LVDTs are being used for and if they might possibly be interchangeable. (We would need to have access to the GE ordering drawings for the LVDTs to say without being on site--and usually only GE has those drawings).

My best guess about your calibration problem is: You're doing something wrong. And unless you have reason to believe the LVDT is damaged you will probably be wasting time and money trying to solve a problem with your procedure by replacing the LVDT.

You could try describing why you need to calibrate the LVDT, what you have done to try to calibrate the LVDT, and if you are using AutoCalibrate and the steps you have performed--along with the results of each step--and we could try to provide some help and direction.

But based on the information provided, we can't do anything. We would also need to know if the Mark V is TMR or SIMPLEX. It's simply not likely that anyone is going to recognize the problem(s) you are experiencing with only the information you provided.
Dear CSA
thanks for the reply...
the problem is ( LVDT core was broken because the actuator shaft was bending ) and we solve the problem of bending , but why the IGV open to the final mechanical open position and not stop on 86 degree ?
even i calibrate the close position to 0.68 to 0.7 Vrms.
i use autocalibrate page in the computer
the required pos. and actual pos. both shows 86 degree in the screen when i open manually to 86 degree but in the site its fully open
i use LVDT under GE part no. 311A5178P002
thanks and waiting your replay

The subject of how AutoCalibrate works and procedures for using it have been covered MANY times in MANY previous threads on For AutoCalibrate to work properly one must know what the position of the IGVs is at BOTH the mechanical stops (closed and open) and those positions must be entered in the proper fields in the file F:\UNITn\ACALIB.DAT. For example, from the factory, the IGV mechanical stops are typically set at approximately 32 DGA and 86 DGA for the normal operating range of 34 DGA to 84 DGA for most GE-design Frame 6B heavy duty gas turbines. When AutoCalibrate is executed it uses the values entered in ACALIB.DAT to know what the IGV positions are at the mechanical stops, because AutoCalibrate isn't able to measure the actual mechanical stop positions--someone has to do that (measure the actual positions at the mechanical stops) and then put the values in ACALIB.DAT for AutoCalibrate to use when performing an AutoCalibration.

AutoCalibrate can't just ”know” what the mechanical stops are set at; those vary slightly from machine to machine. And if you are using the pointer on the axial compressor casing or the IGV actuator ring as the actual IGV position indication, well, that's not usually very accurate, and lots of mechanics use the pointer as if it were a ladder rung when working on the turbine....
IGV LVDT calibration is not just ”point and click.” It's not like calibrating SRV LVDTs or GCV LVDTs (well, it is sort of, but most people don't know how to properly calibrate SRV or GCV LVDTs, either but the chances for error on those devices is a little lower than for errors when calibrating IGV LVDTs).
Using AutoCalibrate is not as automatic as people think--and want to believe--it is. AutoCalibrate only knows what it finds in ACALIB.DAT. Again, this has been written about MANY times before on, and the magnifying glass icon at the top of every webpage can be used to search past threads for that information.
Bending and broken LVDT rods on a GE-design Frame 6B heavy duty gas turbine sounds like a pretty serious issue.... And one that could actually affect the actual IGV mechanical stop settings, which should have been measured/verified after the repair. If the stop settings were measured by the Mechanical Department after the repair you should be able to get the values from the Mechanical Department to enter in ACALIB.DAT. Otherwise you are going to have to use the manual positioning feature of AutoCalibrate to determine the actual mechanical stop settings and then use an ASCII text editor to enter them into the proper fields in ACALIB.DAT in order for AutoCalibrate to work properly.
When replacing an IGV LVDT one does have to set/adjust the LVDT output voltage to approximately 0.700 VAC RMS, +/- 0.020 VAC RMS, when the IGVs are at the closed mechanical stop. It seems you have done that. But it doesn't seem as if you have measured the actual closed and open mechanical stop positions and entered those values in ACALIB.DAT. And most Frame 6B units old enough to have a Mark V using an operator interface running IDOS would have an IGV operating range of 34 to 84 DGA, unless the IGV control had been upgraded in the Mark V. The Control Constants CSKGVMIN and CSKGVMAX will tell you what the operating range of the IGVs is--but the actual mechanical stop positions have to be measured and put into ACALIB.DAT in order for AutoCalibrate to work; the mechanical stop settings are different for just about every unit (even for machines of the same Frame size!!!) and only when AutoCalibrate finds the actual mechanical stop settings as entered in ACALIB.DAT can AutoCalibrate work correctly for calibrating IGVs. This fact is one of the reasons many believed (and some still believe) that AutoCalibrate doesn't work properly for IGVs on units with Mark V control systems.
There is one other possibility that may be causing a problem, and that is if there are processor specific I/O Configurator files on the <I> you are using. Check for the presence of IOCFG_R.DAT and IOCFG_S.DAT and IOCFG_T.DAT in F:\UNITn. If those files exist then it's possible that no matter what success you have with AutoCalibrate they will always cause problems after you put the average 0% and 100% stroke values into the I/O Configurator and download to the control processors and reboot them. Let us know if you find those three files, please.
There is a LOT of information and procedures for using Mark V AutoCalibrate here on available using the Search feature of And many other aspects of Mark* turbine control systems, as well. GE did, and does, a very poor job of documenting most procedures and aspects of Mark* turbine control systems; but a lot of that information has been” captured” here on
Hope this helps!