SRV and GCV Calibration in Cranke Mode


Thread Starter


Dear sir,

As you know if you want to calibrate the SRV & GCV valve, it's easy in offline by forcing some signal like the L43hrJOGX and L4_XTP and need to forcing the L20fgs1&L3adj3.

BUT there is different if use the crank mode?

When i want to do the calibrate in crank the turbine is trip?

So what the important signal most i do forcing even the turbine not shut down.
Please tell the Process Alarms which are active when you put the unit in CRANKe mode in preparation for an LVDT calibration verification.
ALSO, please tell if the Mark V is a SIMPLEX or TMR turbine control panel.

Have you looked at the Trip Display of the operator interface to determine what is "tripping" the unit? (Most all GE Mark V HMIs (the ones that run some version of MS-Windows and CIMPLICITY), and many newer versions of the old <I>s (the ones that ran IDOS), have Trip Displays which could be used (if configured properly!) to determine what is "tripping" the unit. Also, there should be a Start-Check Display, and that can also be used to determine what is preventing the Mark V from displaying a 'Ready to Start'--which is MUST do in ANY mode (other than OFF!!!) to be able to issue a START.

So, it's NOT clear if the unit is actually "tripped" or some start-check permissive is preventing the unit from being started.

Some SIMPLEX Mark V units had some "unusual" functions done in <C> to provide some redundant protection (since there was only an <R> control processor). And, they required an extra step or two to get a 'Ready to Start' for <i>testing</i> purposes.

Lastly, if you are having to manually start the Hydraulic Ratchet pump, then it's likely that the output of the Hydraulic Ratchet pump was re-connected to the high-pressure hydraulic supply to the control valves and IGV actuator (if equipped). That's NOT typical for many GE-design heavy duty gas turbines--even if it seems "normal" for your site. AND< there's a pretty serious concern when using the Hydraulic Ratchet Pump for stroking hydraulically-actuated control devices: I believe, if you look at the L.O. System P&ID (and possibly the Starting Mean P&ID), the Hydraulic Ratchet Pump draws unfiltered oil, which is NOT good for servos, and even the hydraulic self-sequencer.... It's an EXCELLENT IDEA to put differential pressure gauges across any and all filters in the Hydraulic Ratchet system!!! Because, they don't usually have dp gauges--or dp switches to generate alarms in the Mark* turbine control system. So, most filters get so choked (plugged) they eventually rupture.... Which releases a LOT of the trapped debris into the system when the rupture occurs, AND prevents any debris from being trapped in the filter(s).

Anyway, if you need more help, you will need to provide the requested data. AND, it would be great if you resolve your issue with the information provided if you would write back to let us know what you found and how you resolved your issue! A LOT of people read these threads and learn from them--so your feedback is most helpful, even if the information provided was NOT helpful or didn't help you resolve your issue.