Abstract: A starter of single-phase induction motor having main winding and auxiliary winding energized by alternating current power source, including a casing, a positive characteristic thermistor connected in series to the auxiliary winding, an auxiliary positive characteristic thermistor connected parallel to the positive characteristic thermistor, a bimetal, and an enclosed compartment accommodated in the casing for enclosing the snap action bimetal and auxiliary positive characteristic thermistor.

Abstract: When a starting current flows in an auxiliary winding S, a main PTC 12 and an auxiliary PTC 14 generate heat by themselves and the electrical resistance value increases. When the auxiliary PTC 14 reaches 140 deg. C., the snap action bimetal 18 is turned off, and no current flows into the main PTC 12, and starting of the single-phase induction motor 70 is complete. When the snap action bimetal 18 is cut off, slight current continues to flow only into the auxiliary PTC 14 side, and by the slight generated heat, the snap action bimetal 18 is kept in OFF state.