Turbine Rolling

Unit Status Before Turbine Rolling

• Turbo-Generator on Barring gear with all Turbo supervisory parameters are normal.
• Boiler is lighted up condition with one or two oil elevations are I/s.
• HP-LP Bypass is in charged condition.
• Boiler load index is 95 to 100 T/Hr.
• Steam parameter are ready for rolling.
• M.S. Pr. 50-55 Ksc. HRH Pr. 6-8 Ksc.
• M.S. and HRH Tempr. – 320 to 350 DegC

Resetting Turbine

• Reset Master Set Point Release, Reset all Electrical Relays
• Reset Turbine.(Starting Device reduced to 0). Start-up Oil(to open ESV & IV) and Aux start-up oil (to reset  Trip-gear) generate.
• Before opening of Stop vlvs following drains to be kept opened.

1. MS Strainer drains 
2. RH Strainer drains
3. Seat drain before ESVs 
4. Seat drain before IVs.

• HP-IP Trim device on.

Following SLCs of the following equpts are ON

1. Oil p/ps and Turning Gear.
2. LP water injection
3. HPCV Warm-up control vlvs.
4. All drain vlvs.

• Citeria X1, X3 fulfills (MS and HRH Superheat)

Starting Device to be raised to 42%

1. ESV 1& 2 are open.
2. HPCV warm up drain vlvs starts opening.
3. HPCV Surface and Mid Metal Tempr start showing increasing trends and they shouldbe given proper time to stabilize.

RAISE STARTING DEVICE TO 56%

• IV1 AND IV2 ARE FULL OPEN
• Bring the Turbine to soaking speed.
• Before rolling the turbine to soaking speed it is to be ensured

1. TSE to kept on Turbine mode.
2. Criteria curve X4 and X5 for opening the control valves must be satisfied (RECOMMENDED MINIMUM MAIN STEAM TEMPERATURE , HRH Temp AHEAD OF TURBINE BEFORE OPENING THE HP, IP CONTROL VALVES)

• EHC should be ready for operation and Speed controller is active.
• Tracking Device to be kept “ON”.(Starting device to be made 70% in case Tracking Device facility is not available).
• Hydraulic Governor to be kept bypassed by raising the speeder gear to 100%.

Speed Reference is raised to 360 rpm.

• Gate valve Gearing closes at 240 rpm.

Speed raising to 3000rpm

• JOP trips at 540 rpm.
• All Turbo supervisory parameters are normal.
• TSE upper margin > 30 k.
• Criteria curve X6 is satisfied (which ensures the proper warming up of HP Turbine w.r.t. M.S.Temperature)
• The Differential Expansion are within limits.
• The Top & Bottom temperature difference of casing are within limits (35 Deg).
• Sufficient Steam generation in the Boiler to meet the requirement of the Turbine for Block Loading after Synchronization.
• Vibration level to be watched at critical speed at 1500 rpm and 2400 r.p.m.
• AOP can be taken out at 2850 r.p.m.
• All TSI parameters should preferably within normal values.
• Turbine to be soaked at 3000 rpm to fulfill X7 criteria.( RECOMMENDED MAXIMUM MAIN REHEAT TEMPERATURE BEFORE TURBINE IS LOADED)

Generator Synchronization and Block loading

• Load Controller to be switched ON.
• Load Reference to be set to 50 MW.
• Load limit to be set at 60 MW.
• Load Gradient to be switched ON.
• Load Gradient to be set on 10 MW/Min.
• Limit Pressure Mode to be selected.
• Generator Earthing Switch to be opened.
• Bus side Isolator and Generator side Isolator to be closed.
• Generator Protections to be kept on that breaker which is to be closed for joining with
• grid.
• All the Turbo supervisory parameter are checked and ensured that they are normal.

Synchronization Procedure

• Generator Field Breaker closed.
• Generator Terminal Voltage built up to 21 KV by increasing excitation voltage.
• Synchroscope switch kept on CHECK mode.
• Voltage,Frequency of incoming power are matched with the same of running(Grid).
• Generator breaker closed once “In Synchronism” lamp appears at 12O clock Synchroscope needle position. (Rotation of needle should be in clockwise direction).
• Load controller takes up load to 50 MW thus avoiding tripping of Generator on “Low Forward Power Protection”.

After synchronisation and Block Loading

Starting device raised to 100%.

HP-LP Bypass closed.

All MS, HRH, CRH and Cylinder drains are closed after 5% loading has been done.

Turbine Rolling with Hydraulic governor

Turbine has to be reset as usual before rolling.

Following things are to be taken care of before raising Starting device.

Tracking Device Off.

Speeder Gear Position zero.

Speed Reference position zero.

Speed reference raised to 100%.

EHC output goes to 100%.

Starting device position raised to  43%.

ESVS get opened.

Starting device further raised to 56%.

IVS get opened.

Henceforth starting device is raised carefully and speed is brought to 360 rpm by trial and error method.

Turbine soaked at 360 rpm.

Before increasing speed to 3000 rpm

a. TSE upper margin>400.

b. X6 criteria curve satisfied.

Starting device raised to 100% non stop.

a.Turbine speed rises to 2700 rpm.

Hydraulic governor takes over at 90% of rated speed(2700 rpm).

Hence further speed is raised by Speeder gear.

Speeder gear position further raised andspeed is stabilized at 3020 rpm.

Turbine soaked at same speed to fulfill X7 criteria for further loading.

Synchronization and Block loading(by increasing speeder gear) done.