STATOR WATER COOLING SYSTEM OF TURBO-GENERATOR

THE STATOR WINDING OF THE TURBO-GENERATOR IS COOLED BY IRCULATING DEMINERALISED WATER THROUGH HOLLOW CONDUCTORS OF STATOR WINDING BARS IN A CLOSED LOOP.

THE D.M WATER IS FED TO THE FEED HEADER MOUNTED INSIDE THE GENERATOR CASING ON THE TURBINE END.FROM THE FEED HEADER WATER FLOWS THROUTH TEFLON HOSES WHICH CONNECT FEED HEADER TO THE INDIVIDUAL LOWER BARS.WATER PASSES THROUGH LOWER ALONG THE LENGTH TO THE OTHER END AND RETURNS THROUGH THE UPPER BARS OF ANOTHER SLOT AND DRAINS INTO THE DRAIN HEADER ALSO MOUNTED ON TURBINE SIDE AND CONNECTED WITH TEFLON HOUSES TO THE UPPER BARS.THE WATER FLOWING THROUGH THE TERMINAL BAR CIRCULATES THROUGH THE CORRESPONDING TERMINAL BUSHING AND COOLS IT ALSO.

THE PUMP DRIVES THE D.M WATER THROUGH THE COOLERS FILTERS AND WINDINGS AND DISCHARGE INTO A SEPERATE COMPARTMENT OF THE HERMETICALLY SEALED EXPANSION TANK MOUNTED MOUNTED 5M HIGHER FROM CENTRE LINE OF GENERATOR AND MAINTAINED AT VACCUM OF 250-300mm.OF Hg.THE WATER FROM CENTRE THE EXPANSION TANK IS AGAIN DRAWN BY THE PUMP COOLED AND RECIRCULATED.

IF THE PRESSURE OF D.M WATER FALLS IN THE SYSTEM BELOW PARTICULAR VALUE,THE OTHER PUMP AUTOMATICALLY STARTS.THE CLOSED CIRCUIT D,M WATER IS IN TURN COOLED BY D.M WATER SUPPLIED FROM THE STATION D.M PLANT.THE USE OF D.M WATER ON SECONDARY SIDE ELIMINATES ANY ACCIDENTAL CONTAIMINATION OF THE CLOSED CIRCUIT D.M WATER WHICH CALLS FOR TRIPPING AND SHUT DOWN OF THE MACHINE.THE MECHANICAL FILTERS REMOVE FOREIGN PARTICLE IN THE WATER THUS AVOIDING CHOCKING AND EROSEN OF FILTERS OF HOLLOW CONDUCTORS.THESE FILTERS SHOULD BE PERIODICALLY CLEANED ONE BY ONE.THE CHOCKING OF FILTER IS INDICATED BY DIFFERENCE IN INLET AND OUTLET PRESSURES.MAGNETIC FILTERS CHECK MAGNETIC PARTICLES FROM ENTERING HOLLOW CONDUCTORS.THE EXPANSION TANK PROVIDES CONSTANT LEVEL OF WATER DURING NORMAL RUNNING AND HAS MAKE UP PROVISION FROM TURBINE CONDENSATE SYSTEM OR D.M PLANT.A WATER JET EJECTORS CREATES NECESSARY VACCUM IN EXPANSION TANK.

AN ELECTRONIC LEVEL SIGNALLING DEVICE GIVES ALARMS FOR HIGH AND LOW LEVEL IN THE EXPANSION TANK.ONLY STAINLESS STEEL CONNECTING PIPES ARE USED IN THIS SYSTEM.THE WATER FLOW IS MEASURED THROUGH AN ORRIFICE PLATE ALONG 3NO OF DIFFERENTIAL PRESSURE TRANSDUCERS.THESE TRANSDUCERS SEND IMPULSE TO THE FLOW METERS ON SIGNALLING AND ANNUNCIATION PANNELS AND FLOW RECORDER IN CONTROL ROOM.THERE IS PROVISION FOR ALARM AND TRIPPING FOR AND EMERGENCY FLOW AND RESISTIVITY WHEN TWO OUT OF THREE METERS/RECORDERS SHOW EMERGENCY FLOW.

THE SPECIFIC RESISTIVITY IS CONTINUOUSLY MEASURED BY DEVICE WHICH PASSES ELECTRICAL IMPULSE TO INDICATING AND SIGNALLING DEVICE MOUNTED IN U.C.B.THERMOMETERS AND PRESSURE GAUGES ARE MOUNTED FOR MONITORING TEMPERATURES AND PRESSURES AT VARIOUS POINTS.A STARTING PANEL FOR MOTORS AND ANNUNCIATION PANEL FOR CONTROLS HAVE BEEN PROVIDED.