| 摘要 |
PURPOSE:To make an ignition device small-sized and low in its loss by intermitting a gate current to a thyristor switch in accordance with a current flowing to a capacitpr for compensating a reactive power. CONSTITUTION:A current transformer 10 for detecting a capacitor current, a comparator 8 for comparing a detected current value with positive and negative set values, an AND element 9 for executing an AND operation of an output of the comparator 8 and an output from a turn-on and turn-off control device 5, and a monostable element 11 are added to this system. In ths state, if an instantaneous value of a capacitor current detected in an on-period of a thyristor switch 3 exceeds a prescribed level, a gate current is cut off, and if said value is below the prescribed level, the gate current is supplied only for a prescribed time when the monostable element 11 is operated. In this way, an ignition device can be made small-sized and low in its loss. |
