09-11-2012, 06:19 PM
500 MW GENERATORS
500MW Generator.ppt (Size: 1.25 MB / Downloads: 105)
GENERAL
18 sets are in operation in India
More sets under manufacture for NTPC
Oldest is in operation since January 1984
High availability, almost 100% PLF
Non stop operation > 406 days at Ramagundam STPS of NTPC.
660 MW TGs being planned by NTPC
THDF: VENTILATION SCHEME
Gas flow path 1 enters rotor on Turbine end and cools rotor overhang and slots.
Gas flow path 2 cools stator core.
Gas flow 3 enters rotor on exciter end & cools rotor overhang & slots, as well as stator core end parts at both the ends.
Hot gas from all paths returns through air gap to compressor, and to coolers.
COOLANT TEMP. CONTROL
Load changes lead to mechanical stresses. They are due to expansion of core iron,winding copper,insulation and due to their unequal thermal expansion coefficients.
CW flow to Hydrogen coolers is varied with load automatically, to achieve uniform temperatures.
CONSTRUCTION
Built in end shields bearings.
Core suspended by 21 flat springs at bottom and sides to dampen vibrations
Mild steel pressure plates and axial studs keep core tight.
Core axial studs are insulated.
Core ends are shielded from axial fields by H2 cooled magnetic iron flux shields