SOLID STATE ELECTRONIC MOTOR STARTERS.

Solid state motor starters obviate the limitations of conventional motor starters by achieving motor protection and control through fully static electronic feedback circuits and are of two basic designs: one type retains the electromechanical contactor for motor switching whereas the other design employs a static contactor for this purpose. Builtin circuitory contains static negative sequence and overload current relays which have adjustable inverse time-current characteristics, a contactor voltage control system, an annunciation system and current monitored star to delta changeover. The need of using separate single phasing preventors, stalling protection relays and the replacement of contactor operating coils or contacts are eliminated in these starters.