GB513812A - Improvements in and relating to automatically re-closing switching arrangements - Google Patents

Abstract

513,812. Protective cut-out systems. AKT.- GES. BROWN, BOVERI, & CIE. July 25, 1938, No. 22003. Convention date, July 31, 1937. [Class 38 (v)] Relates to a switching arrangement for interrupting arc short-circuits by rapidly opening and immediately reclosing the circuit, thus reducing the number of interruptions in the supply, the switching arrangement comprising a power switch and disconnecting switch in series, which are normally manually opened, whereas on fault, only the power switch is opened. According to the invention, if the fault persists after at least one operating cycle of the power switch, both switching points are automatically opened to produce the final disconnection. A separate protective relay may be provided for each switching point, operation of the separating point being also dependent on the final opening of the power switch. Alternatively a single relay may control both points. When a fault occurs in the line a, the distance or other protective relay d closes and energizes, over contacts of a change-over relay h, the operating coil f of the power-switch b, which at once opens with the series-disconnecting switch c opening: The relay d then restores and the relay h changes over the connections from coil f to the coil g by means either of the relay d or of the switch b. The switch b recloses automatically after, say, 0.1 seconds, and if the fault is only transient, the relay h is restored to the position shown after a suitable time-delay. If, however, the relay d operates again owing to persistance of the fault, the coil g is energized and opens the line a permanently at the switches b, c, which are structurally interconnected to allow of this. Relay h is then returned to the position shown but may alternatively be timed to permit a succession of openings and reclosures of switch b before it changes over to coil g. A push-button k provides for manual opening of the combination b, c, and in reclosing after a complete fault disconnection or manual opening, circuit is finally made at c. The switch b preferably has arc-quenching means to ensure rapid interruption of the circuit, and a further disconnecting switch may be arranged in series with b, c.