Abstract: An auto-recloser for a power line has a high voltage closing coil (12) for closing the main contact (14) in the power line, the closing coil being energized via a non-latching switching (18) in turn controlled by a low voltage closing coil (20). A time closing pulse is applied to the low voltage coil (20) to close switch (18) for a very short time period. A coil protection (24) monitors the status of the main contants (14) and if these have not closed after a preselected time period of typically 100 ms then the protection circuit opens a normally closed switch in series with the low voltage coil (20) to prevent further closing pulses being applied in further attempts to close the main contacts (14).

Abstract: Fault currents in the phases of a three-phase supply are detected by transformers 28 in respective phase links 14 and are counted by associated circuits 24 when any one of the circuits 24 reaches a predetermined count level, or when there is a fault condition, a low VA trip coil 42 is energized so as to release latches which hold the phase links 14 in their operative positions and thereby cause all three links 14 to drop out together.

Abstract: Electrical switchgear comprises a first contact set composed of a first contact which is pivotable about a pivot axis and a second contact, the contacts being relatively movable between a closed position wherein a load current can be passed therethrough and an open position. An arc is formed between the first contact and an arcing electrode during movement of the contacts from their closed to their open position, whereupon current flows through a field coil connected in series with the electrode to produce a magnetic field which causes the arc to rotate and become extinguished. The pivot axis of the first contact extends transversely to a major axis of the field coil such that, during opening of the contacts, an end portion of the first contact moves transversely to and inwardly of said major axis. A second contact set is operable to earth the first contact set when its contacts are in their open position.

Abstract: A gas-blast type interrupter comprises first and second electrodes relatively movable between a closed position in which they are in mutual electrical engagement and an open position in which they are mutually separated, movement of the electrodes towards their open position causing an arc to be drawn therebetween. A tubular housing encloses the first electrode and has therein a first insulating orifice through which the second electrode substantially sealingly passes when the electrodes are in their closed position. A guide surrounds the tubular member and has therein a second insulating orifice through which the second electrode also substantially sealingly passes when the electrodes are in their closed position, the first and second orifices being co-axial and of essentially the same size.