Damper Winding Fault Analysis in Synchronous Machines

A Damper winding performs an important function of protecting the Synchronous Motors (SMs) during transient operations. They also happen to be one source of concern for failure of SMs, which are otherwise quite reliable. The situation aggravates when the motors are fed by variable frequency drives, which brings additional stress on the damper bars. This paper presents theoretical simulations of a salient pole SM with twelve poles, containing three damper bars in each pole, during healthy as well faulty damper bar conditions. The current distribution is calculated in each damper bar. Experiments were conducted on the same SM and the current in the damper bars as well inter-connecting poles were measured and captured on a rotating wireless communication platform, both during healthy and faulty conditions of the damper bars with varying severity. The fault indicators are presented to detect damper bar failure conditions, thereby helping preventive maintenance of SMs.