| 摘要 |
PURPOSE:To restart a single-phase electric motor smoothly and surely when it is stopped by a momentary service interruption. CONSTITUTION:A single-phase electric motor is provided with a main winding 1A and an auxiliary winding 1B which are connected in parallel with an AC power supply 3 and with positive temperature coefficient thermistors 5A, 5B which are connected in series with the auxiliary winding 1B. The single-phase electric motor is constituted in such a way that two of the positive temperature coefficient thermistors 5A, 5B are arranged and that the two positive temperature coefficient thermistors 5A, 5B are connected alternately to the power supply 3 by a relay 4 which is changed over automatically in a power failure. In this case, it is desirable that a ratchet relay is used as the relay 4 and that the positive temperature coefficient of the two positive temperature coefficient thermistors 5A, 5B is made nearly equal. |
