| 摘要 |
<P>PROBLEM TO BE SOLVED: To obtain a highly practical switch controller capable of effectively controlling a surge voltage that is generated when a circuit is reclosed, without requiring a special voltmeter which measures a residual DC voltage of a no-load transmission line. <P>SOLUTION: A zero point interval detection circuit 21 detects in detail the time intervals of output zero points from a current transformer 8. When a difference between the time intervals of the zero points, which arise after the opening time and detected by the zero point interval detection circuit 21, and half period of a commercial frequency of an AC voltage exceeds a predetermined amount, an interruption time judgment circuit 23 judges as an interruption time the time of a zero point precedent to the one where it is detected that the difference exceeds the predetermined amount. A making time determination circuit 24 detects an inclination at the interruption time of a main circuit current. When the inclination is positive, a phase in which the AC voltage becomes a negative maximum value is determined as a making time. When the inclination is negative, a phase in which the AC voltage becomes a positive maximum value is determined as the making time. <P>COPYRIGHT: (C)2008,JPO&INPIT |
