| 摘要 |
PURPOSE:To enable to prevent the propagation of an accident even if a vaccum valve can be disconnected, by a method wherein auxiliary contacts are mounted between contacts for a tap selector and vacuum valves, and the contact parting time of the auxiliary contact is controlled. CONSTITUTION:Auxiliary contacts H1 and H2 are mounted between contacts TS1 and TS2 of a tap selector and vacuum valves V1 and V2, respectively. The contact H2 is constituted such that, in the case of switching from a tap TAP1 to a TAP2, after a vacuum valve V3 extinguishes arc, it opens before the valve V2 closes. In the case of changing-over from the TAP1 to the TAP2, if a vacuum breakdown occurs to the valve V1, arc is intermittently produced even if the contact is opened. If the valve V2 is closed under said condition, the taps are shorted, but the contact H1 opens at a point of time preceding a current point of time. This permits the taps to be prevented from shorting. In case a vacuum breakdown occurs in the vacuum valve V3, arc is intermittently generated, but the contact H1 is opened, which results in extinguishing the arc. |
