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How to take turbine Barring gear

      How to take Turbine Barring gear                          

How to take turbine Barring gear

Physical Checks before barring gear

·         Ensure no PTW is pending
·         No man is working in AOP-1 & 2, OVEF-1 & 2, AC JOP, DC JOP, and DC EOP.
·         Ensure Turbine Generator is ready to put into Service.
·         Take clearance from Respective Departments.
·         Ensure Lube oil Tank level >60%
·         Ensure AOP is running & lube oil header pressure>1.9 Kg/cm2.
·         Ensure OVEF running condition.
·         Ensure SFG oil system is ON condition.

Permissive for start-up

·         AOP-1 & 2, OVEF-1 &2, AC JOP, DC JOP, and DC EOP Start permissive coming from MCC.
·         Any Bearing temperature not very high (< 90oC).
·         Motor winding temp not very high (< 125oC).
·         Emergency local push button to be released.

Startup sequence

Normally after any shutdown of TG when the same is started it has to start from standstill condition.
Start Barring gear.
  • Ensure Lube oil pressure > 1bar.
  • Turbine axial shift < ± 0.6mm.
  • Ensure DC EOP/AOP is a running condition.
  • Ensure AC JOP not in local.
  • After checking the Release SFG Turning gear gives ON command to it from FG condenser unit.
  • Ensure DC JOP starts ON auto & switch off automatically, these steps ensure the healthiness of DC JOP.
  • Ensure JOP-1 is running & discharge pressure >210kg/cm².
  • Ensure Turning gear auto on.
  • Ensure TG shaft gets engaged to turbine gear & TG starts rotating with turning gear ON condition & reaches 80 rpm.
  • AC JOP on & DC JOP off.
  • Turning gear on
After a trip out or shutdown of TG the following sequence to be followed to ensure Turning gear operation
  • Ensure AOP/DC EOP starts in auto otherwise starts in manual & ensure bearing pressure >0.9bar.
  • Ensure AC JOP (DC JOP in case of power failure) starts at 300 rpm of TG OR starts manually.
  • Ensure JOP discharge pressure >210kg/cm².
  • Ensure Turning gear in auto ON condition.
  • If the Turning gear is in auto ON condition then selected either of the JOP & display for making STG ON will appear, make STG ON.
  • AT 10 rpm the Turning gear start engaging with slow forward, slow reverse action of turning the gear. After the Turning gear get engaged to the main TG shaft gear, the TG shaft will start rotating with a signal forward on the Turning the gear screen.
  • Ensure Turning gear speed is increasing from 10 to 80 rpm after turning the gear engaged.
  • If Turbine speed is less than 4 rpm, then start hand barring from local near Turbine after pressing the Turning gear engage pushbutton provided at local panel.

Operation monitoring & control

  • Monitor TG parameters during rolling & normal operation
  • Check Lube oil system, bearing metal temperature, etc.

Shutdown Procedure:

After any trip out when the TG is put for rolling operation, with the opening of Turbine control valves its speed starts increasing.
  • This the machine has got a mechanical arrangement that as the speed increases, the Turning gear gets auto disengaged.
  • However if the  Turning gear does not get disengaged beyond 200 rpm, trip the TG.
  • At 300 rpm JOP gets switches off automatically, if not switch it off manually.

In case the Turbine is going for shutdown & to be brought to standstill condition, then the Turning gear can be switch off.
  • Ensure the Turbine flange temperature <100°C.
  • Ensure there is no sealing steam, i.e. FG sealing steam off
  • Give stop command to FG Turning gear.
  • Ensure STG gets off command & turning gear gets disengaged.
  • Turbine speed comes down < 4 rpm.
  • Now running JOP switches off automatically or switches it off manually.
  • Complete FG Turning gear cycle
Best practices followed (If any): Not applicable

Exception/ Emergency handling   :
IN case of AC failure, DC EOP & DC JOP to be taken into service.

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