The retardation method for bearings loss determination

A new method for determining bearings losses of a synchronous generator, based on measurement of the speed change during mechanical and electrical braking, is described in this paper. During the mechanical and electrical braking, the total braking torque of the hydrogenerator is made up of the torques defined by single losses. In this paper, the torque-speed curve is represented by the corresponding equations which describe all the torques occurring during mechanical or electrical braking. Based on the proposed equations, speed change is obtained and compared with the speed response, which is measured in the hydro power plant Djerdap (in Serbia). Also, obtained results for unknown losses are compared with calculated values. The proposed method has the most economical use when applied to large synchronous machines.