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SRV Calibration in AUTO mode with Mark V
Procedure for SRV calibration in AUTO mode with Mark V


I do not have a Mark V, Mark VI or Mark VIe system nearby to check for myself what I want to know. That's why I resort to asking it here.

When I have to calibrate the Speed Ratio Valve (SRV) with a Mark V control system in MANUAL mode, initially I have to change the regulator type of the SRV (which, originally, I think is 77) by the regulator 43 (the same regulator of the GCV). After the calibration is completed, the regulator corresponding to the SRV is placed back into the system. My question is: should I make that change if I do the calibration in AUTO mode? Or the system is responsible for doing what corresponds without any intervention on our part.

And the calibration of the SRV with a Mark VI or Mark VIe in AUTO mode, would be the same procedure as with a Mark V in AUTO mode?

Kind regards,


Yes; Mark V AutoCalibrate automatically changes the servo-valve output regulator type from a Type 77 to a Type 43 when an SRV is selected. And, when the work on the SRV is complete and AutoCalibrate is exited, or another servo-operated device is selected, AutoCalibrate automatically returns the regulator back to a Type 77 from a Type 43. (A Type 77 regulator is a pressure control loop with position feedback. A Type 43 regulator is a position control loop. If you pass a reference to a Type 77 regulator, it will be looking for pressure feedback--because the reference from the CSP for the SRV is in pressure. The SRV would just go full open with a reference and 0 psig (barg) feedback; that's why the regulator type has to be changed to a position control loop, and the reference, in percent (of position) can then be compared to the LVDT feedback for control of the SRV.)

>And the calibration of the SRV with a Mark VI or Mark VIe in
>AUTO mode, would be the same procedure as with a Mark V in
>AUTO mode?

The procedure the user performs differs from that of the Mark V. AND, the way the pressure control loop function of P2 (Interstage) pressure control is performed is different in most Mark VI's and Mark VIe's. The pressure control portion of the SRV control scheme is accomplished in application code (the "CSP" of the Mark VI and Mark VIe). And the output of that control function, in percent, is passed to a position control loop (essentially a Type 43 regulator in Mark V terms). So, no; neither the Mark VI nor the Mark VIe changes the SRV regulator type for MOST SRVs. (I believe there were some early Mark VI control systems that still used pressure control-with-position feedback regulators, so as with most things GE-related, there are no absolute guarantees).

Hope this helps!

By Voyager2 on 28 May, 2019 - 2:51 pm


I am very satisfied with the first answer about Mark V calibration in AUTO mode, and although I have to investigate a bit more about calibration on Mark VI and Mark VIe, I could get very useful information "hidden" into your explanation: I was always wondering what did the application code mean or how could I handle it. I can interpret, from you answer, that application code in Mark VI/Mark VIe is equivalent to the the CSP (that I know better) in Mark V, and that is very important to me.

Well, I will investigate a little more about the calibration of the SRV with Mark VI/Mark VIe. I think that is not a big deal, but I want to make sure of all these procedures to execute them when necessary without even think of it.

Thanks a lot.


Thank you for the feedback!!!