What is VH14 task in GE Gas Turbine?
Do any one has some drawing or manual about it?
VH14 is the device number for the Hydraulic Ratchet Self-sequencer. You can find this in the Device Summary drawing, where it lists the device number, a description, and the ML (Model List) for the Piping Schematic (P&ID) drawing where you can see a schematic diagram of the device in one of the systems of the gas turbine and auxiliaries.
[ML numbers are a kind of "shortcut" to a drawing description. For example, every GE-design heavy duty gas turbine has a L.O. System Piping Schematic drawing, and that drawing has a part number that is specific to that unit. Every L.O. System Piping Schematic drawing has the same ML number, 0418, or 418. So, when someone says to look at ML 418 they mean to look at the unit-specific L.O. System Piping Schematic drawing for the turbine being worked on. All of the systems which would have Piping Schematic drawings have ML numbers, usually in the 0400-0499 series. A complete list of the Piping Schematic Drawings for each unit is usually on one of the first pages of the unit's Device Summary drawing.]
As for a written description of how VH14 works, you should be able to find something in the Instruction Manuals provided with the turbine and auxiliaries by the turbine packager. GE-packaged units have System Descriptions with the same names as the Piping Schematic drawings and have brief descriptions of the workings of the system and the devices in the system.
VH14 is usually found on the Starting Means Piping Schematic drawing, so the tab in the GE-provided Instruction Manual would be titled 'Starting Means' where one could find the System Description for the Starting Means system.
A recent thread on control.com had some good information about how VH14 worked in conjunction with the ratchet mechanism: http://www.control.com/thread/1266452920.
VH14 is usually a complete assembly, made up of several components. If you read through the above thread you can find the name of the manufacturer and possibly contact them for help with your query. I don't know if they sell individual components, or even if they sell the device (you may have to buy it from GE directly). And I doubt that GE sells every individual component for the device.
Having said that, I'm sure there are industrious people in the world that have found components so as not to have to buy entire assemblies from GE or the OEM. It seems to be a game for many people, to find ways to buy comparable equipment from anyone but the OEM. And the people who play the game are obnoxiously ebullient when they find ways of doing so. One would think they'd won the Irish Sweepstakes jackpot of 300,000,000.00 Euro the way they strut and crow about their accomplishment.
But, they're still coming to work every day, at the same place, just like everyone else.