Ours is frame 6B gas turbine. we put the unit on ratcheting after the unit was down for about two month due to low gas supply. we found out that the unit was ratcheting on forward stroke continuously and without retraction on backward stroke.

The following items were checked:

VPR6 prss regulatory valve checked
20cs is on continuously.

33HR condition not yet confirmed, 33cs was checked found okay. The ratcheting and clutch circuit could not be traced.

Could anybody help, please.
Regards.
Dottey.

 

See this very recent thread:

http://www.control.com/thread/1266452920

It's not clear what you mean when you say the "circuit could not be checked." Electric? Hydraulic?

You say it's continuously on "forward stroke"; is the jaw clutch continuously rotating in the forward direction? (Because it can't! It must not be rotating at all, or it's almost imperceptibly moving, which would mean there is insufficient pressure from the hydraulic ratchet pump.)

Have you checked the hydraulic ratchet pump?

It's presumed the unit has a hydraulic ratchet self-sequencer, VH14. Have you replaced it?

There should also be filters in the hydraulic ratchet oil piping; have they been replaced?

You need to confirm that 33HR is working properly. It should change state when the ratchet reaches the end of the forward stroke, and also when it reaches the end of the retraction stroke. It's usually the "permissive" for when to stop the ratchet, as the normal sequence is for the ratchet to reach the end of a forward stroke, 33HR to change state indicating the end of a forward stroke, the ratchet to retract and upon reaching the end of the retraction stroke that 33HR will change state again, and the ratchet will start another forward stroke, and then approximately 3 seconds after the forward stroke starts the Speedtronic will stop the ratchet for approximately 3 minutes, after which time the sequence will repeat. End of forward stroke; 33 HR changes state; end of retraction stroke; 33HR changes state; approximately 3 seconds into forward ratchet operation ceases for approximately 3 minutes. And so on.

 

What was done during this two months outage? What has been changed? What are the alarms present while ratcheting is on and off?
Check proper functioning of L33CSE and L33HRF. Malfunction of any of these could result erratic ratchet function. So be sure that they are changing state during sequencing. Also check 43HR, if it is shorted, Turbine may turn continuously.

M M Ahsan.