Abstract: 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.

Abstract: An electrical fault protective device for providing power interruption in electrical circuits rated up to 10,000 amperes and above. The device comprises a single- or double-vented expulsion-type fuse, connected at one vented end to a hollow bus and at the other end to a conductive expansion chamber for a double-vent fuse or an electrical contact for a single-vent fuse. A spring located in the hollow bus is attached to the fusible link for pulling the fusible link from the fuse tube to rapidly extinguish the arc when the fuse blows. The fuse tube is also retractable into the hollow bus when the fuse blows to provide a visual indication of fuse operation and to relieve the dielectric stress on the fuse tube.

Abstract: 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.

Abstract: An electrically conductive expulsion fuse manifold and bus for connecting and mounting a plurality of fuses which upon operation expel gases into the manifold is shown and described. The expulsion fuses are attached to the manifold by means of clamps, flanges, and/or threaded connections. Each expulsion fuse includes an expendable cap which may be blown off into the manifold under high magnitude capacitor discharge currents and/or fault currents for safe double-vented fuse operation. The manifold may also be non-conductive where electrical isolation is required and where a separate electrically conductive bus is employed.

Abstract: An overload and fault protector for a distribution transformer or the like is disclosed. A series-connected high range current-limiting fuse and a low range expulsion type fuse is provided with a transformer lead disconnect or ejection mechanism to insure a rapid, positive disconnect of the transformer or other power distribution circuit components. The ejection mechanism supports the transformer lead and completes the circuit to the fuse link assemblies. Upon separation of the fuse link, the ejection mechanism operates to quickly disconnect the transformer lead minimizing voltage stress on the fuse assembly and providing visible indication of a blown fuse.

Abstract: An load interrupter is disclosed having the characteristics of an ordinary puffer interrupter and a self-extinguishing gas flow interrupter. The load interrupter comprises a generally hollow cylinder which is adapted to be filled with an arc extinguishing fluid and which has an electrically insulated nozzle at one end. A piston is sealingly and slidingly disposed within the cylinder so as to be movable between a first and second position to change the internal volume of the cylinder that is in flow communication with the nozzled end. A stop limits the relative motion between the piston and the nozzled end of the cylinder. A spring biases the piston against the stop. One of the two contacts across which the arc is formed is carried by the piston. The other contact is operated by a prime mover to move into and out of the chamber formed by the piston, cylinder and nozzle. Thus, under low current conditions, the piston follows the movement of the other contact.

Abstract: A disconnect switch is disclosed having a puffer interrupter electrically connected with and operated by a knife switch or fused disconnect switch. A puffer interrupter includes a divided pressure chamber having at least one exterior wall which is flexible and responsive to the pressure therein. A fixed tubular electrical contact is carried by a fixed interior wall within the puffer interrupter housing so as to establish flow communication through the fixed interior wall. A floating electrical contact is carried by the flexible wall and is adapted to engage and disengage from the fixed electrical contact in response to movement of the flexible wall. A snap spring biases the floating contact away from the fixed contact during arc interruption.