Raychem Limited

Chuck F Cooper

John Seymour Mattis

Jeffrey A Bennett

William M Robinson

A surge arrester (1) includes varistor elements (2) forming a stack (3) and having opposed end surfaces (4a, 4b). The varistor stack is electrically connected via the opposed end surfaces to end terminals (7a, 7b) having circumferential ridges (32a, 32b), which, in the event of failure of the varistor elements, are designed to relocate the resulting arc and direct it in a manner which reduces or minimizes damage to the surge arrester. The ridges serve as damage-tolerant sacrificial rooting points for an arc in the event of varistor element failure by presenting a substantial metal mass for the arc to erode away.

Surge arrester having ridged terminals

A surge arrester has end terminals having circumferential ridges, which, in the event of failure of varistor elements of the surge arrester, are designed to relocate the resulting arc and direct it in a manner which reduces or minimizes damage to the surge arrester. Grooves lead from the inner surface of the terminals to the ridges, to facilitate arc relocation.

Surge arrester having grooved and ridged terminals

A surge arrester includes varistor elements forming a stack and having opposed end surfaces. The varistor stack is electrically connected via the opposed end surfaces to end terminals having circumferential ridges, which, in the event of failure of the varistor elements, are designed to relocate the resulting arc and direct it in a manner which reduces or minimizes damage to the surge attester. The ridges serve as damage-tolerant sacrificial rooting points for an arc in the event of varistor element failure by presenting a substantial metal mass for the arc to erode away.

A surge arrester has a single varistor element or a stack of varistor elements held between two end terminals by a plurality of elongate strength members disposed therearound. The ends of the strength members are inserted into recesses in the end terminals. Crimping of the end terminals distorts the recesses sufficiently to hold the strength members firmly therewithin, but without shearing and crushing (or otherwise damaging) the strength members.

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Mountain View, CA, United States of America

Chuck F Cooper