Abstract: A power transformer having an operating temperature in excess of 200.degree. C. and including a casing or tank, an electrical core and coil assembly having an asbestos based barrier material and being supported in said casing, and a low cost saturated hydrocarbon insulating fluid substantially filling the casing and having a vapor pressure at 200.degree. C. less than 10 millimeters of mercury and a flash point in excess of 230.degree. C.

Abstract: An adjustable transformer core and the method of manufacturing an adjustable transformer core, the transformer including a core and coils, the core being formed from a plurality of lamination sets, each lamination set including a number of legs and a pair of yoke members, the lamination sets being stacked in face-to-face relation so that the legs can be moved relative to each other. The coils may be wound directly on the legs and are moved toward each other to obtain predetermined characteristics. The coils are enclosed within a pair of core clamps to retain the relative position of the coils. Such adjustment can be employed to obtain different impedance or insulation levels. It is also within the contemplation of this invention to use the core as a common core for a variety of transformer designs.

Abstract: An oil immersible current limiting full range fuse including a tubular housing, end caps hermetically sealed to each end of the housing and supporting a full range fuse assembly within said housing, the housing being filled with a granular arc extinguishing filler, the hermetic seal provided between the housing and the end caps is formed by a resilient gasket mounted at each end of the housing and epoxy adhesive provided in the end caps, the adhesive being displaced by the gasket on insertion into the space between the end cap and the outer wall of the housing.A method for testing the hermetic seals for leaks which includes the steps of injecting sulfur hexafluoride into the housing, sealing the housing, confining the fuse in a closed space for a predetermined period of time and testing the atmosphere of the confined space to determine the presence of sulfur hexafluoride.

Abstract: A high voltage bushing for an electrical device such as a transformer, the bushing including a fixed cylindrical conductor and a gas actuated bore contact mounted for reciprocal movement in the conductor and a fixed current interchange device in the form of an annular spring mounted in the conductor for maintaining electrical communication between the bore contact and the conductor.

Abstract: A high voltage bushing having a bore contact mounted for axial movement within the bushing housing, the bore contact being biased for movement into engagement with a rod contact and a magnetically responsive trip mechanism releasably engaging the bore contact and being responsive to a magnetic field produced under fault current conditions to release the bore contact for movement into engagement with the rod contact.

Abstract: An electrical connector system including a cable terminator having a conductive probe and a bushing having a bore contact mounted for reciprocal movement in an electrically conductive tubular member and a fusible member positioned between the bore contact and the conductive member, the fusible member being connected to fuse in response to fault current produced by a prestrike arc to increase the pressure within the tubular member to force the bore contact into electrical engagement with the probe in the terminator.

Abstract: A high voltage fuse of the current limiting type including a housing of insulating material, a cylindrical support formed by an inorganic asbestos thread or string threaded on end plates which are mounted in a spaced relation on a support rod, the thread forming a cylindrical support for a fusible element which is spirally wrapped about the cylindrical support. An arc quenching material is used to fill the housing and completely surround said fusible element.

Abstract: The unique, relatively nonflammable, environmentally safe, insulating oil comprises a saturated hydrocarbon oil having a molecular weight of about 500 to about 700, and a fire point above 200.degree. C. The electrical equipment comprises an oil-sealed tank, a unique insulating oil filling said tank, and an electrical component such as a conductive coil immersed in said insulating oil. A method of filling the oil-sealed tank of an electrical apparatus with the unique insulating oil also is disclosed.

Abstract: In a high voltage bushing having a hollow tubular bore contact engageable with the probe of a high voltage cable terminator, a nose shield for reducing corona around the probe on close-in of the terminator with the bushing, the nose shield being formed of a conductive cylinder which is embedded within the bushing housing but is electrically isolated from the conductive cylinder in the bushing and is electrically connected to the conductive insert of the terminator on close-in.

Abstract: A solid state inverse overcurrent relay having a long slender wire connected to respond to a current which is proportional to the line current in a power system. An infrared detector or phototransistor is positioned to sense a predetermined color of radiation from the wire and is connected to fire a silicon controlled rectifier which is connected in series with a trip coil for a circuit breaker. The trip coil and silicon controlled rectifier are connected to an independent DC power source. The long slender wire on energization responds to the current which is proportional line current with the same time current characteristic as a fuse. In an alternate embodiment of the invention the relay is connected to the power system through a bridge rectifier which provides the DC current for operating both the heat responsive wire as well as the infrared detector.

Abstract: A temperature sensing transformer primary switch for a distribution transformer, the switch being mounted within the distribution transformer below the level of the dielectric fluid and being manually operable externally of the transformer for opening the primary circuit and deenergizing the transformer, the switch including a temperature sensing device mounted on the internal end of the transformer below the level of the dielectric fluid to open the primary switch in response to overload temperatures produced on the transformer's secondary circuit. The temperature sensing device includes a compression spring and a wax motor for releasing the energy stored in the compression spring as the temperature of the dielectric fluid reaches a predetermined maximum temperature. The spring is preloaded sufficiently by a manual operation to actuate the switch at the maximum temperature. A pressure responsive switch assembly is provided for opening the primary switch.

Abstract: A ground contact adaptor for a high voltage cable having a metallic tape shield, the adaptor including a contact sleeve assembly having an electrically conductive band connected to a copper braid partially embedded within a conducting rubber contact sleeve and extending outwardly therefrom to form a ground contact, a spring biasing the band into electrical engagement with the metallic tape shield of the high voltage cable and a conducting rubber sleeve sealingly engaging the contact sleeve and cable insulation to form a water-tight seal around the band.

Abstract: A quick-make, quick-break probe contact assembly for connecting a high voltage cable to a high voltage bushing, the probe contact assembly being mounted in a cable terminator and including a movable section responsive to either an arc-generated arc-extinguishing gas, or to a fuse generated gas pressure for accelerating close-in with the bushing under fault current conditions. The probe contact assembly can also include a spring biased snap release sleeve that is retained within the bushing on load break of the cable terminator from the bushing to accelerate arc-out.

Abstract: A fused high voltage electrical bushing having a housing formed of a ceramic dielectric material, porcelain or glass, and having an axially extending passage, an electric terminal at each end of said passage, a fusible element within said passage interconnecting the terminals, a granular dielectric material completely filling the passage, a conductive layer of material on the inside surface of the passage, and a heat insulating sleeve positioned in the passage between the granular dielectric material and the inside surface of the housing to insulate the housing from the heat of the arc on interruption.

Abstract: A ground level transformer unit including a transformer and a pallet-pad, the pad being formed from a lightweight material and having on one side supporting surfaces of sufficient strength to form a pad mount base for the transformer and a surface for transporting the transformer unit by a fork lift truck and on the other side a number of latching points for accommodating a number of different size transformers, and a tamper proof ridge positioned to correspond to the dimensions of the various size transformers. The pad is permanently attached to the transformer for installation on site. The transformer units can be stacked for storage and shipped as a unit.

Abstract: A fused high voltage electrical bushing adapted to be mounted at the entrance in a casing to an electrical apparatus to provide a connection between a high voltage cable and the electrical apparatus, the bushing including a housing formed of a dielectric material and having an axially extending passage, an electrical terminal sealed to each end of said passage, a fusible element within said passage, interconnecting the terminals, and a granular dielectric material completely filling the passage; a layer of electrically conductive material is provided on the inner surface of said passage and extends through the entrance in the casing to the electrical apparatus, the inner layer of material being spaced from and electrically connected to the element, and a layer of electrically conductive material on the outer surface of said housing for forming a stress cone at the entrance of the casing to said apparatus, the stress cone being grounded through said casing, the inner and outer layers cooperating to reduce volt

Abstract: A high voltage fault interrupter including a vacuum interrupter having a fixed contact and a movable contact, a trip mechanism module connected to said movable contact, said trip mechanism module monitoring the power line for conditions which call for circuit interruption, a dielectric housing completely enclosing said interrupter and said trip mechanism module, the housing including a flexible dielectric interface, and an actuating and reset module connected to said trip mechanism module through the flexible dielectric interface. The trip mechanism module can include contact position and fault condition indicators within the dielectric housing which are visible externally to indicate the condition of the interrupter. The high voltage interrupter can include a hydraulic interphase trip module which is responsive to fault opening of the vacuum interrupter for providing a hydraulic pulse to a second and third circuit interrupter connected in the same system.