Description of GSU Transformer 

The GSU (Generator Step-Up Transformer) for thermal power plants is a core connection device between the power generation system of thermal power plants and the transmission grid. Its main function is to step up the low-voltage alternating current (typically 10kV–20kV) output by the steam turbine generator in thermal power plants to high voltage (such as 110kV, 220kV, 500kV and above). This reduces line losses during long-distance power transmission and enables efficient integration of electrical energy into the grid. It directly receives the electrical energy generated by the generator, serving as a "bridge" for power output from thermal power plants. Its operational stability directly affects the power generation efficiency of the plant and the safety of the power grid, and it is widely used in supporting various thermal power units such as coal-fired and gas-fired units.

• 3-Ph, 850MVA/400kV, GSU Transformer, ONAN/ONAF

• 1-Ph 400MVA/1000kV, ODAF in 1000MW power plant,

• 3-Ph 1140MVA/500kV GSU Transformer, ODAF
  

Features of GSU Transformer

• Adapting to high-temperature and high-load conditions: Designed for the continuous operation and large load fluctuations of thermal power plants, it uses high-temperature-resistant insulating materials (e.g., Nomex paper) and enhanced cooling systems (mostly forced oil circulation air cooling/water cooling). It can withstand short-term overvoltage and overcurrent impacts at the generator outlet for a long time.

• High insulation and short-circuit resistance: The windings adopt a tightly wound process and reinforced insulation structure, which can resist electromagnetic force impacts during short-circuit faults. They also tolerate harmonic interference that may exist in the thermal power plant grid, reducing the risk of insulation aging.

• Large capacity and voltage adaptability: The capacity ranges from tens to hundreds of MVA (e.g., 300MVA, 600MVA), and the voltage level matches the output grid requirements of thermal power plants (110kV–1000kV). It can be custom-designed according to unit capacity (300MW, 600MW, 1000MW, etc.) to ensure power matching.

• Integrated protection and monitoring functions: Equipped with built-in safety devices such as gas relays and pressure relief valves, some models are fitted with intelligent sensors. These can real-time monitor oil temperature, winding temperature, and insulation status, supporting remote early warning, which meets the operational needs of unattended or minimally attended thermal power plants.

• Long service life and low maintenance requirements: Core components (iron core, windings) use high-permeability silicon steel sheets and high-purity copper wires, combined with a sealed oil tank design to reduce oil degradation and component losses. The design life is usually over 30 years, lowering the full-life-cycle maintenance cost.

1-Ph 400MVA/1000kV, ODAF in 1000MW power plant

3-Ph 1140MVA/500kV GSU Transformer, ODAF