| Seijiro Muramatsu | Power Electric Machine Design Dept., Hitachi Works, Power Systems, |
| Kenichi Hattori | Power Electric Machine Design Dept., Hitachi Works, Power Systems, |
| Kazuhiko Takahashi | Fourth Dept. of Systems Research, Hitachi Research Lab., |
| Akihito Nakahara | Fourth Dept. of Systems Research, Hitachi Research Lab., |
| Kengo Iwashige, Dr. Eng. | Power & Industrial Systems R&D Lab., Power Systems, |
These days, in the light of the attention given to environmental protection, high-efficiency electric power generators are in great demand. Among such generators, air-cooled turbine generators offer the benefits of easy operation and maintenance at low cost. On the other hand, in contrast to hydrogen-cooled generators, it is difficult to increase their capacity and efficiency. In particular, improving their performance under 60-Hz operation, a rotation speed at which loss is large, is being demanded. With these circumstances in mind, Hitachi has developed a 250-MVA, 60-Hz air-cooled generator (called an inner-cooler type). Applying various technologies—starting with reducing airflow volume and mechanical loss by optimizing the ventilation structure as well as equalizing temperatures and lowering electrical loss by optimizing stator-coil strand arrangement—this generator achieves high efficiency close to that of a hydrogen-cooled generator, namely, 98.8% (ANSI), under 250-MVA, 60-Hz operation at a power factor of 0.85. Combining the advantages of large capacity and high efficiency with ease of operation and maintenance, this development has given birth to air-cooled generators that can match the high efficiency of conventional hydrogencooled generators.
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The Hitachi Hyoron (Japanese Only) |
generator, air cooled, high efficiency, large capacity, 250 MVA
