| 摘要 |
<p>PURPOSE:To prevent generation of transient phenomenon exerting adverse effect on a system or equipment under any switching condition by setting an opening timing of the contact piece of a breaker at the increasing portion of an absolute current value between zero point and a peak value of a breaking current. CONSTITUTION:A switch timing controller 7 determines the ON/OFF state of a breaker 2 on the basis of a signal output from the auxiliary contact 33 or the like of the breaker 2. In case of the ON state of the breaker 2, it is confirmed on the basis of an input signal from a current measuring transformer 4 that a current is zero. A microprocessor 73 counts for a predetermined period after zero point of the current upon input of a break command. An output unit 75 is activated when the count value reaches between zero point and a peak value at 1/4 cycle, thereafter and a driven unit 76 is driven. Therefore, the break operating coil 31 of the breaker 2 is excited so that a contact piece is opened.</p> |
