M501G Series

Gas Turbines
  • Standalone Gas Turbine Output

    270-280 MW class

  • Combined Cycle Output

    400-430 MW class / 800-860 MW class / 1,280 MW class

  • Combined Cycle Efficiency

    More than 60%

High-performance large-capacity gas turbines for 60 Hz power generation

In February 1997, the first unit of the 1,500°C Class M501G gas turbine came into commercial operation. This series features the use of steam for cooling combustors. The GAC Series, which is the current mainstay model, adopts the latest air-cooled combustors in place of conventional steam-cooled combustors. It uses compressor discharge air for cooling combustors to add operational flexibility by eliminating the need for steam for cooling from the bottoming cycle.

Overall Design

The gas turbine unit is based on the basic structure adopted in the early 1970s that has accumulated a track record of at least 40 years. Its main features are as follows:

  • A compressor shaft end drive reduces the effect of thermal expansion on alignment
  • A rotor with simple single-shaft two-bearing support
  • A rotor structure has bolt-connected discs with the torque pins in the compressor section and CURVIC couplings in the turbine section to ensure stable torque transmission
  • An axial flow exhaust structure advantageous in combined cycle plant layouts
  • Horizontally split casings that facilitate field removal of the blades with the rotor in place


Axial flow compressors designed with advanced airfoil design technologies are introduced. They feature large capacity, high efficiency and a high pressure ratio. Variable inlet guide vanes ensure operational stability at the start-up and enhanced performance at partial load in combined cycle operation.


A premixing low NOx combustor is a steam-cooled type, composed of one pilot burner and eight main burners that surround it. The combustor has an air bypass mechanism that enables fuel-air ratio regulation in the combustion region.

Incorporating air-cooled combustors, the GAC series adds operational flexibility by eliminating any need for steam cooling from the bottoming cycle.


Four-stage axial flow turbines in a three-dimensional aerodynamic design are adopted. The vanes at the first three stages are air-cooled. Among these, those at the first two stages adopt directionally solidified (DS) materials with thermal barrier coating (TBC). Despite the rise in temperature, application of advanced cooling technologies and the TBC helps to maintain the metal temperature of turbine blades at the level of conventional gas turbines.



M501G1 M501GAC
Compressor Number of Stages 17 17
Combustor Number of Cans 16 16
Cooling Method Steam Cooled Air Cooled
Turbine Number of Stages 4 4
Rotor Number of Rotors 1 1
Output Shaft Cold End Cold End
Rated Speed 3,600 rpm 3,600 rpm
Gas Turbine Approx. L × W × H 12.9 × 5.1 × 5.5 m 12.9 × 5.1 × 5.5 m
Approx. Weight 295 ton 295 ton

Simple Cycle Performance

M501G1 M501GAC
Frequency 60 Hz 60 Hz
ISO Base Rating 267.5 MW 283 MW
Efficiency 39.1 %LHV 40.0 %LHV
LHV Heat Rate 9,211 kJ/kWh 9,000 kJ/kWh
8,730 Btu/kWh 8,531 Btu/kWh
Exhaust Flow 612 kg/s 618 kg/s
1,349 lb/s 1,364 lb/s
Exhaust Temperature 601 °C 617 °C
1,113 °F 1,143 °F
Exhaust Emission NOx 15ppm@15%O2 15ppm@15%O2
CO 9 ppm@15%O2 9 ppm@15%O2
Turn Down Load 50 % 50 %
Ramp Rate 18 MW/min 18 MW/min
Starting Time 30 minutes 30 minutes

Combined Cycle Performance

M501G1 M501GAC
1 on 1 Plant Output 398.9 MW 427 MW
Plant Efficiency 58.4 %LHV 60.5 %LHV
2 on 1 Plant Output 800.5 MW 856 MW
Plant Efficiency 58.6 %LHV 60.7 %LHV
Starting Time

Performance Correction Curves

  • Effects of Compressor Inlet Temperature on Gas Turbine Performance (Typical)

  • Effects of Barometric Pressure on Gas Turbine Performance (Typical)


Typical Plant Layout - 1 on 1 configuration, single-shaft

  • Gas Turbines
  • Steam Turbines
  • Generators
  • Inlet Air Filter
  • Heat Recovery Steam Generator (HRSG)
  • Electrical / Control Package
  • Main Transformer
  • Condenser

Typical Plant Layout - 2 on 1 configuration

  • Gas Turbines
  • GT Generator
  • Steam Turbines
  • ST Generator
  • Inlet Air Filter
  • Heat Recovery Steam Generator (HRSG)
  • Electrical / Control Package
  • GT Main Transformer
  • ST Main Transformer
  • Condenser

Main Delivery Records


KEILCO Ilijan (The Philippines)
1,250 MW, 4 x M501G


Datan Power Plant, Taiwan Power Company (Taiwan)
4,200 MW, 8 x M501G & 6 x M501F


Shin-Nagoya Thermal Power Station Group 8, Chubu Electric Power Co., Inc. (Japan)
1,600 MW, 4 x M501G


Sakaiko Power Station, the Kansai Electric Power Co., Inc. (Japan) (Photo courtesy of the Kansai Electric Power Co., Inc.)
2,000 MW, 5 x M501G

Recent Orders

Number of units x Series Year of start of operation Plant specifications
Carty Generating Station, Portland General Electric (PGE) (USA) 1 × M501GAC 2016 Combined cycle
Wildcat Point Generating Facility, Old Dominion Electric Cooperative (ODEC) (USA) 2 × M501GAC 2017 Combined cycle
Toyama Shinko Thermal Power Station, Hokuriku Electric Power Company (Japan) 1 × M501GAC 2018 Combined cycle
Middletown Energy Center, NTE Energy (USA) 1 × M501GAC 2018 Combined cycle
Kings Mountain Energy Center, NTE Energy (USA) 1 × M501GAC 2018 Combined cycle