| 摘要 |
PURPOSE:To prevent the load of an AC power source from abruptly increasing when a motor is started by detecting the current or power consumption of an AC motor, comparing the measured value with its reference value and a time gradient, and feeding back its output. CONSTITUTION:The current consumption of an AC motor 5 is detected by a current detector 9, and its output is applied to an arithmetic unit 11 together with a reference current value and its time gradient from a setter 10. The unit 11 detects the deviation between the measured value by the detector 9 and a reference value by the setter 10, controls a drive circuit 8 during the prescribed time immediately after the power source is energized such as, for example, during only 60sec., and holds the switching element 7 always in ON state after the lapse of the prescribed time. |
