Abstract:
An overcurrent relay circuit, the pickup value of which is substantially independent of the DC-component in an asymmetrical alternating current, has an input transformer, the magnetic circuit of which is provided with air gaps while the secondary load of this transformer is high-resistive. To the secondary winding of the transformer is connected a rectifier with a smoothing device connected to level-sensing circuit and an output magnetic relay in the output circuit of the level-sensing circuit.
Abstract:
An overvoltage protection device for a DC transmission line connecting two stations, each station including several seriesconnected converters each provided with a bypass member, has a series of lightning arrester units connected between the transmission line and earth. At least all but one of the lightning arresters has a bypass device. Relays for closing the bypass devices to short circuit the lightning arresters are connected to the bypass members for the converters in such a way that the number of bypassed lightning arresters corresponds to the number of bypassed converters.
Abstract:
A static converter station connected to a DC transmission line over a DC reactor is provided with lightning arrester protection means which includes a spark gap stack connected to the DC line and provided with a starting mechanism for its ignition, and with an arrangement responsive to earth faults in the station to control the starting mechanism to trigger the lightning arrester.
Abstract:
A socket for mounting and connecting electrical devices having pin outputs is formed of a lid and a boxed-shaped bottom part. The lid has a plurality of holes arranged in pairs for receiving pins, while the bottom part has a hollow opposite each pair of holes for receiving a connecting element formed with pairs of tongues for detachable locking contact elements inserted from the lower side of the bottom part. Between rows of pairs of holes on the top part are three holes arranged in a vertical row, opening into a recess in the bottom side of the bottom part. A shortcircuiting device insertable into the recess has a pair of contacts for receiving pins inserted through the two outermost of the three holes and a movable short-circuiting contact engageable by a pin passing through the central hole.