An investigation into damper winding failure in a large synchronous motor

This paper deals with operational issues related to a 36-MVA, 11-kV synchronous motor used to drive a reciprocating compressor in a process industry. Extensive damage to the motor´s damper winding was discovered during routine maintenance. The paper identifies possible operational issues that are believed to have contributed to the development of fault, presents a simplified analytical model of the damper winding and makes recommendations aimed at identifying similar failures at an early stage.