Cooper Industries, Inc.

Cooper Power Systems, Inc.

Stanley S Kershaw

Gary L Goedde

Edward F Veverka

Stephen P Johnson

David R Miller

John F Baranowski

Jeffrey J Kester

Robert N Schettler

Jonathan J Woodworth

A surge arrester for mounting on a transformer having two line-potential terminals and a neutral terminal. The arrester includes two high energy, low voltage metal oxide varistor disks, each MOV disk having one side connected to an electrode that is electrically connected to one of the line-potential terminals and having the other side of the MOV disks electrically connected to a neutral electrode that is electrically connected to the neutral terminal of the transformer. The MOV disks shunt any current surge to ground upon the application of a predetermined voltage across the disks. In the preferred embodiment, the electrodes and MOV disks are housed within a thermoplastic elastomer housing filled with a potting compound of a resilient elastomeric material. The potting compound completely insulates and seals the electrical connections and MOV disks. Further, the materials of the housing and potting compound are resilient so as to easily vent gases formed during short circuit within the arrester and thereby prevent fragmenting.

Low voltage, high energy surge arrester for secondary applications

A non-fragmenting surge arrester with a staged pressure relief mechanism includes a liner with outlets formed in the walls thereof, a gas expansion chamber within the liner and a housing having weakened-wall regions adjacent to the outlets in the liner. Ionized gas formed by an internal failure is vented from the expansion chamber through the outlets and, upon generation of sufficient pressure, fractures the housing at the weakened-wall regions. In this manner, the generated gas forms a lower impedance path for the current which is thereby shunted around the failed internal components, preventing the generation of further internal pressure which could cause a catastrophic failure of the arrester.

Non-fragmenting arrester with staged pressure relief mechanism

An arrester for an under oil transformer is connected between a primary bushing lead and an insulator/isolator penetrating the wall of a housing which encloses the oil, arrester, and transformer parts. A ground wire outside the housing is removably connected to the isolator which functions as a circuit disconnector. The ground wire is removed to open circuit the arrester so that the transformer may be tested without having to disable any parts in the housing. Responsive to an arrester failure, the ground wire is blown away to give a visual indication of the failure. The blowing away of the ground wire eliminates the need for the arrester to fail in an open circuit condition.

Arrester with external isolator

A fail-safe, non-fragmenting surge arrester includes a liner having outlets formed in the walls thereof for venting ionized gases generated within the liner by internal arcing. The vented ionized gas forms a lower impedance path for the current which is thereby shunted around the failed internal components, preventing the generation of internal pressure which could otherwise cause a fragmenting failure mode of the arrester. The internal components include stacked varistor elements and may include an internal fuse link electrically in series with the varistors.

Growing community of inventors

Portville, NY, United States of America

Stanley S Kershaw