A
system (120) for preheating a
bimetal protector (126) of a
single phase motor (122) equipped with a first run
capacitor (CR) and optionally a second run
capacitor (CR-H). A first and optionally a second pair of normally closed fixed contacts (132;133) are operable by a
bimetal element or disc (128).. There may be provided an optional first preheating element (134). A second preheating element (135) is supplied via the first or second run
capacitor. The second pair of contacts (133) may connect the second
heating element (135) to the first or second run capacitor (CR;CR-H). The first pair of fixed contacts are operable, so that the second
heating element is supplied when the first pair of fixed contacts is open, i.e. at the occurrence of a locked rotor fault of the motor. A single
bimetal disc may serve to open the first pair of fixed contacts (132) and to close the second pair of fixed contacts (133). The protector automatically resets after a controllable time
delay following activation.The invention concerns a
starter for a line start
electric motor having at least one main winding ( 4 ) and at least one start winding ( 12 ) and which start winding is connected in series with a run capacitor ( 14 ) with which a start capacitor ( 17 ) and a PTC-
thermistor ( 19 ) are connected in parallel. In order to make a simply constructed
starter for a line start
electric motor the start capacitor ( 17 ) and the PTC-
thermistor ( 19 ) are connected in series with a switch mechanism ( 20 ). The series connected circuit made up of the start capacitor ( 17 ), the PTC-
thermistor ( 19 ) and the switch mechanism ( 20 ) is connected in parallel with the run capacitor ( 14 ).