Can the LVDT on an GCV or SRV be maintained online without tripping the turbine?


The answer is: Based on the information provided, no. And, it would be necessary to know more about what LVDT maintenance entails in this thread to give a better answer, too.

You have chosen to include absolutely zero information regarding the valves, the number of LVDTs per valve, the type and manufacturer of the turbine control system or the problem(s) which are perceived to be occurring. And, you are probably wanting a detailed procedure for attempting to do so.

GE-design heavy duty gas turbines, even those of a particular Frame size (such as Frame 5 or Frame 9E) are exactly like automobiles made by the same manufacturer, for example Toyota Corolla's. Every year, the design changes a little bit (or, sometimes a lot), and the accessories and auxiliaries even in the same model year can be VERY different, as can the engine(s) and/or transmission(s) or even the wheels and/or tires.

There were GE-design heavy duty gas turbines produced with single LVDTs on servo-operated devices (early in the product lifecycle) and there are SIMPLEX, DUAL Redundant and TMR control systems. There are also analog, hybrid and digital turbine control systems as well as different types of control systems applied to turbine control. The possibilities are endless and myriad.

LVDTs, AND servo's, get improperly blamed for a huge number of perceived (as well as real) problems for which they are not even remotely possible of causing or solving.

It would be SOOOOO great if there were only one Frame 6 design or one Frame 7F design (by extension I am referring to ALL GE-design heavy duty gas turbines) and every problem could be solved with a single question. But, it just ain't so. There are some units, with redundant LVDTs and redundant controllers in the turbine control system that could possibly be ”maintained” (whatever that means) without shutting the unit down. But, to do so would require a very good understanding of the situation (real or perceived) and the associated pertinent facts--none of which were offered or provided in the original post. And which would take a lot of back-and-forth (repeated questions and answers) to even begin to understand and formulate a plan or response--if it were even possible.

The purpose of this reply is to encourage the original poster --and ANYONE who might read this thread--to, first, understand that every gas turbine and it's accessories and auxiliaries and control system, IS NOT THE SAME. Second, it's generally the case that some basic information and details are required to receive a meaningful response (and this response is, for all intents and purposes related to this specific question) is meaningless. Well, that's not exactly true. Based on the information provided by the original poster the response is completely appropriate--if meaningless.

Help us to help you. It's as simple as that (even though a full procedure for such a request as this would be difficult to write even if all parties had all the necessary documents and information). While ”maimtenance” (whatever that means) on a running unit might be possible, the possibilities for tripping the unit while attempting to do so are very high.

Perhaps if ANSWER provided some basic information ((real or perceived) problem or issue; number of LVDTs on each valve: type of control system and number of controllers) we might be able to offer suggestions or ideas. But not without more information.