Fig.3 Expanded capacity range of indirect-cooled generators

Expanded capacity range of indirect-cooled generators

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In addition to temperature test shown in Fig.2, three-phase sudden short-circuit and shock response tests were conducted to evaluate the resistance of high thermal conducting stator coils against excessive electromagnetic forces at fault, and no abnormality on stator coils was confirmed. An application of newly developed high thermal conducting insulation system and the optimized ventilation system can bring the following advantages.

(1) 10 to 20% increase in unit capacity of indirect-cooled generators with the same frame size is available, and an initial cost of generators can be reduced.
(2) As shown in Fig.3, the design range of indirect hydrogen-cooled generator capacity can be expanded up to 600MVA class while the direct water-cooling was applied to conventional design in this capacity range. Generator stator structure can be significantly simplified by deletion of the stator coil cooling water passage. And also the deletion of related auxiliary system and monitoring system brings the improved reliability of unit operation and reduction of maintenance cost.
(3) The production lead-time of large capacity generator can be remarkably reduced by the deletion of many parts and production processes related with stator coil cooling water passage. (1), (2), (3)

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