Single phase induction motor with two windings - with auxiliary winding current controlled by PTC resistor which heats up to close open circuit

摘要

The auxiliary winding (3) is in series with a parallel combination of a capacitor (4) and a PTC resistor (5). The object of the circuit is to give enhanced starting performance. At starting the PTC resistor (5) has a low value, and a high current flows throug the winding thus assiting in giving a high strating torque. As the PTC resistor heats up its resistance becomes high and in effect becomes an open circuit. The motor then continues to run with a capacitor linked auxiliary winding and the main winding (2).