The M-o Valve Company Limited

Eev Limited

Kenneth George Cook

Clive Anthony Roberts

Richard John Seddon

Cliff Robert Weatherup

Colin Archibold Pirrie

High coulombic switch gas discharge device

A switch for switching large currents and large charges includes an anode separated from a cathode with a cylindrical trigger electrode located around the anode and the gap. The cathode is of a metal such as zinc, cadmium, tin or magnesium. During operation, a suitable potential applied to the trigger electrode causes a main discharge to occur between the anode and the cathode.

Switching arrangements wherein a cylindrical trigger electrode is

A circuit arrangement for protecting a load connected across a supply against surge voltage includes a gas-filled arrester connected in parallel with a semiconductor arrester across the load. A firing circuit is provided which is responsive to the breakdown of the semiconductor arrester to apply a voltage between a trigger electrode in the gas-filled arrester and another electrode within the gas-filled arrester to reduce the breakdown voltage of the discharge gap of the gas-filled arrester. The arrangement is operative for protection against surge voltages between the supply lines, and also between each line and earth.

Surge voltage protective circuit arrangements

A surge voltage protection arrangement for a load 10 connected to an A.C. supply 8 comprising a gas-filled excess voltage arrester 11 connected in series with a capacitor 12 across the load 10. The value of the capacitor 12 is chosen such that the largest expected surge pulse which causes the arrester 11 to fire will not charge the capacitor to such an extent that the voltage then applied across the load 10 exceeds that of the A.C. supply 8. The arrangement enables the arrester 11 to recover after such a surge pulse within a fraction of an A.C. supply cycle, thus avoiding placing an unnecessary load on the arrester. A resistor 13 whose resistance is of a value such that the capacitor 12 is able to discharge through it within one half cycle of the A.C. supply may be connected across the capacitor 12.

Surge voltage protection arrangements

An excess voltage arrester of the kind comprising a gas-filled enclosure having an electrode structure (1, 11, 13) within the enclosure which defines at least one discharge gap. A portion of at least one electrode (13) is adapted to melt on overheating of the arrester so as to take up a generally spherical form (19) under the action of surface tension and thereby contact another electrode (1).

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Northwood, United Kingdom

Kenneth George Cook