Advanced calculation of temperature rises in large air-cooled hydro-generators

During the design of large air-cooled synchronous machines for hydro power plants special attention must be paid to efficient cooling of the machine. It is necessary that the design engineer gets a complete picture of the losses, the cooling airflow and the temperatures inside the different parts of the machine. Not only the active parts but also the end regions of stator and rotor must be carefully checked. This paper presents a new calculation method which is based on an iterative numerical coupling of power losses, airflow and temperature calculation. This computation gives a complete overview of the temperature gradient in the stator core, the stator winding including overhang and the pole coil.