4.3 STEAM TURBO GENERATOR
4.3.1 Turbo Generator
The purpose of the generator shown in Figure (4.14) is to convert the mechanical power delivered from the turbine to the rotor coupling into electrical power, in the form of voltage and current, at the main generator terminals. The generator is built to withstand a wide range of abnormal operating conditions including e.g. negative sequence loads and sudden short circuits.
The design described is of a two pole, full speed turbo-generator with hydrogen gas cooling of all internal components. The stator casing is firmly anchored to the foundation and carries the stator core and the stator winding. The casing has hydrogen-gas coolers arranged vertically in each corner. The stator end-shields close the stator casing and carry the shaft seals.
The rotor is rigidly coupled to the turbine, carries two single stage axial-flow fans for circulating the hydrogen-gas coolant inside the machine. The rotor runs on three separate pedestal bearings, which are rigidly fixed to the foundation and effectively decouple rotor and stator vibrations.
The electrical power is taken out at the main terminals of the generator. Each end of each phase is brought out. Access to the generator for inspection and service is provided via the cooler housings once the coolers are withdrawn. The pedestal bearings and the seals are readily accessible, not requiring any special tools for dismantling.
At major revisions the rotor can be withdrawn without taking off the end shields. Due to its simple design the whole rotor including the winding gas passages can be inspected. The two non-driven-end bearings are double-insulated to allow easy checking of the insulation during operation. The brushes can be changed during operation.
4.3.2 Cooling Of Turbo Generator
The generator is entirely cooled by hydrogen as primary coolant in a closed circuit. The heat is then transferred to the water circuit (secondary coolant) via the hydrogen/water coolers. The hydrogen is circulated by two axial fans mounted to the shaft. The hydrogen cooling system consists of two parallel cooling circuits symmetrical to the generator mid plane.
4.3.1 Turbo Generator
The purpose of the generator shown in Figure (4.14) is to convert the mechanical power delivered from the turbine to the rotor coupling into electrical power, in the form of voltage and current, at the main generator terminals. The generator is built to withstand a wide range of abnormal operating conditions including e.g. negative sequence loads and sudden short circuits.
The design described is of a two pole, full speed turbo-generator with hydrogen gas cooling of all internal components. The stator casing is firmly anchored to the foundation and carries the stator core and the stator winding. The casing has hydrogen-gas coolers arranged vertically in each corner. The stator end-shields close the stator casing and carry the shaft seals.
The rotor is rigidly coupled to the turbine, carries two single stage axial-flow fans for circulating the hydrogen-gas coolant inside the machine. The rotor runs on three separate pedestal bearings, which are rigidly fixed to the foundation and effectively decouple rotor and stator vibrations.
The electrical power is taken out at the main terminals of the generator. Each end of each phase is brought out. Access to the generator for inspection and service is provided via the cooler housings once the coolers are withdrawn. The pedestal bearings and the seals are readily accessible, not requiring any special tools for dismantling.
At major revisions the rotor can be withdrawn without taking off the end shields. Due to its simple design the whole rotor including the winding gas passages can be inspected. The two non-driven-end bearings are double-insulated to allow easy checking of the insulation during operation. The brushes can be changed during operation.
4.3.2 Cooling Of Turbo Generator
The generator is entirely cooled by hydrogen as primary coolant in a closed circuit. The heat is then transferred to the water circuit (secondary coolant) via the hydrogen/water coolers. The hydrogen is circulated by two axial fans mounted to the shaft. The hydrogen cooling system consists of two parallel cooling circuits symmetrical to the generator mid plane.
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