Good evening everyone in the Great house.
One of our gas turbine fails to ratchet after shutdown and according to the operator in charge they have boxed the unit till after 48hours to return to cool down it self then we will now troubleshoot. So my question now is as an Instrumentation and control personnel what are the things that might caused the problem and after checking the starting clutch solenoid valve which resistance values is okay.
The signal name of the alarm that comes up from the HMI was "G2L30HRX1" Ratchet trouble.
Thanks for usual cooperation

 

Akin,

What SHOULD be happening is this: The Aux. L.O. Pump should be placed in HAND (Manual) operation, and if the motor starter won't allow that then the output of the Mark* that drives the Aux. L.O. Pump should be forced to start and run the Aux. L.O. Pump. This is to keep L.O. flowing to the bearings to keep them coo l as the interior temperatures of the turbine decrease.

Cooldown operation should be forced OFF--that way the unit will not keep trying to ratchet, which can damage the ratchet AND can also prematurely start the unit rotating before it has sufficiently cooled.

And, then, wait at least 24 hours--48 is also good--for the interior of the unit to cool and for the turbine-generator shaft to begin to return to straight after it sags while it is hot. It won't go completely straight--but it will go near enough to straight that it can be rotated with ratchet without damaging anything, and it can be CRANKed after a few hours of Cooldown to further the straigtening of the shaft.

As for what might have caused the problem--there is insufficient information to be able to say with ANY degree of confidence or certainty. We also don't have a SINGLE CLUE as to the Frame size of the GE-design heavy duty gas turbine experiencing the problems, or what kind of ratchet mechanism is used for Cooldown (internal to the torque converter; external to the torque converter; etc.). Nor do we know anything about the age of the machine, it's care and maintenance and how it's been operated.

Imagine I wrote to a World Wide Web forum and said my watch stopped working, and asked what could be the cause. Wouldn't you like to know if the watch has a mechanical mechanism or is electronic? Does it have a face with hands that move, or is it a digital watch? If it is is mechanical watch wouldn't you like to know if it was recently wound? (Or if it has an self-winding feature?) If it is an electronic watch wouldn't you like to know if the display shows any characters or information at all, or if it's blank (which might indicate a dead battery)? Would you ask if the battery had been recently changed? Would you like to know when it quit working--such as after being in a puddle of water for 4.5 hours, or found at the bottom of a swimming pool or after being dropped two stories to the ground?

Help us to help you. We are not there with you. We can't see what you can see. We don't even know how you measured the coil resistances to know if it was done properly. We don't know what you know. We know that many GE-design heavy duty gas turbines use a hydraulic ratchet mechanism for Cooldown operation--but what you apparently don't know is that there are different types of ratchet mechanisms. Some are fully controlled by the Mark*; others are controlled by a self-sequencer which get a signal from the Mark* and sends a signal to the Mark*. Some starting means (of which the ratchet mechanism is usually a part) are connected to the turbine shaft via a jaw clutch; others via a SSS clutch (Shifting, Self-Synchronizing); still others have no clutch between the starting means and the turbine shaft.

So, there's simply too much we don't know. Every GE-design Frame n (where 'n' could be 3 or 5 or 6 or 7) IS NOT like every other GE-design Frame n. Just because there are thousands of Frame 5s and Frame 6s and Frame 7s doesn't mean they are all alike or have the same auxiliaries (like ratchet mechanisms). Is every Mercedes sedan like every other Mercedes sedan? Is every Timex watch like every other Timex watch? Is every Rolex Oyster watch like every other Rolex Oyster watch?

You want help. We need information.

It's as simple as that.

It would also be VERY helpful to know what Mark* is used to control and protect the turbine and auxiliaries. AND, it would be great to see a CLEAR PHOTO of the rung L30RX1 (photos can be attached to Control.com threads using the 'Attach files' button at the bottom of the edit window).

Lastly, if you don't like what I wrote but you still want some information about ratchet problems, there is almost 20 years of posts here on Control.com about GE-design heavy duty gas turbine problems and controls-related issues--all searchable using the 'Search' feature at the top of every Control.com webpage. There is a WEALTH of information about many things--and ratchet trouble has been discussed many, Many, MANY times before on Control.com. (We know; that means you have to read multiple threads and none of them ask EXACTLY the question you have or they are not entirely, 100% applicable to your site and your turbine and your needs. BUT, you WILL learn a LOT if you do read through multiple threads, and you will most likely be able to put together a list things to check and eliminate as you work to troubleshoot and resolve the issue at your site. Just sayin'..... Try it; you might like it.)

Write back with more information, and you will most likely get a better reply. (Maybe even from a more patient person than CSA...! What the heck--it's worth a try!)

Blessed day.

 

We are waiting !!

 

The gas turbine controller is Mark VI
Frame 6b.

 

NoReport ??

 

glenmorangie,

Another poster hoping that by opening a thread on a World Wide Web forum with one piece of information (but wait--now we have three pieces of information!) the expert(s) can(will) know immediately what the problem is and how to solve it without even a screwdriver or a wrench. No understanding of the systems or the equipment; it's just a ratchet that's not working--oh, and the solenoid coil circuit has some resistance so it must be okay, right?

I fear for this world that automation has created and promised so much of. Who can tell which is the artificial intelligence--the control system or the human user?