With the remarkable improvements in gas turbine technology, many combined cycle power plants have been constructed both in domestic utilities and overseas. Against this back ground, and in pursuit of further improvements in plant efficiency, which is the greatest merit of the combined cycle power plant, Mitsubishi Heavy Industries, Ltd. Has constructed a multi-shaft, reheat type 670 MW combined cycle power plant as No. 5 Unit at the Himeji No. 1 Power Station of The Kansai Electric Power Co., Inc. The gas turbines used for this plant are the 501 F type which are the latest, high efficiency, large capacity machines having a turbine inlet temperature of 1 350 degrees centigrade. In April 1995, the plant started commercial operation and has provided excellent performance together with high reliability.