Design of high temperature induction motor for application in sodium cooled fast reactor control system

Prototype Fast Breeder Reactor (PFBR) employs induction motors of various power ratings in high temperature ambient and sometimes corrosive atmosphere. Safe operation of the reactor depends on robustness and reliability of induction motors in its critical components. Safety related systems such as shutdown and online inspection systems, utilize induction motors as actuators in their mechanisms. Since external cooling is not permitted in control and inspection motors, special design of motors is required to withstand high temperatures. This paper deals with design, analysis, fabrication and testing of a compact 50 W, three phase induction motor, suitable for operating up to 250 °C ambient with winding temperature withstand capability up to 550°C. The designed motor was analyzed with two dimensional Finite Element Model (FEM) code FEMM to study the torque slip characteristics and magnetic flux density patterns in stator and rotor.