Abstract: The present invention comprises a mixture of hydrocarbons having a well-defined chemical composition that is suitable for use as a dielectric coolant in electrical equipment in general, and specifically in transformers. The dielectric coolants of the present invention are particularly suited for use in sealed, non-vented transformers, and have improved performance characteristics, including decreased degradation of the paper insulating layers, as well as a greater degree of safety and environmental acceptability. The present dielectric coolants comprise relatively pure blends of compounds selected from the group consisting of aromatic hydrocarbons, polyalphaolefins, polyol esters, and natural vegetable oils, along with additives to improve pour point, increase stability and reduce oxidation rate.

Abstract: The present invention comprises a mixture of hydrocarbons having a well-defined chemical composition that is suitable for use as a dielectric coolant in electrical equipment in general, and specifically in transformers. The dielectric coolants of the present invention are particularly suited for use in sealed, non-vented transformers, and have improved performance characteristics, including decreased degradation of the paper insulating layers, as well as a greater degree of safety and environmental acceptability. The present dielectric coolants comprise relatively pure blends of compounds selected from the group consisting of aromatic hydrocarbons, polyalphaolefins, polyol esters, and natural vegetable oils, along with additives to improve pour point, increase stability and reduce oxidation rate.

Abstract: The present invention comprises a mixture of hydrocarbons having a well-defined chemical composition that is suitable for use as a dielectric coolant in electrical equipment in general, and specifically in transformers. The dielectric coolants of the present invention are particularly suited for use in sealed, non-vented transformers, and have improved performance characteristics, including decreased degradation of the paper insulating layers, as well as a greater degree of safety and environmental acceptability. The present dielectric coolants comprise relatively pure blends of compounds selected from the group consisting of aromatic hydrocarbons, polyalphaolefins, polyol esters, and natural vegetable oils, along with additives to improve pour point, increase stability and reduce oxidation rate.

Abstract: The present invention comprises a mixture of hydrocarbons having a well-defined chemical composition that is suitable for use as a dielectric coolant in electrical equipment in general, and specifically in transformers. The dielectric coolants of the present invention are particularly suited for use in sealed, non-vented transformers, and have improved performance characteristics, including decreased degradation of the paper insulating layers, as well as a greater degree of safety and environmental acceptability. The present dielectric coolants comprise relatively pure blends of compounds selected from the group consisting of aromatic hydrocarbons, polyalphaolefins, polyol esters, and natural vegetable oils, along with additives to improve pour point, increase stability and reduce oxidation rate.

Abstract: An electrical apparatus, such as a transformer, includes an expandable internal chamber that is nonventing and completely and permanently sealed from the ambient environment. The chamber houses a core and coil assembly or other current-carrying conductor and is completely filled with dielectric fluid having a pressure less than one atmosphere. The enclosure walls are flexible and are permitted to bow inwardly and outwardly as the volume of the dielectric fluid changes due to thermal expansion and contraction. A method of processing the dielectric fluid and filling and sealing the transformer at sub-atmospheric pressure is also disclosed.

Abstract: A surge arrester particularly suited for secondary side protection of distribution transformers, includes a low-voltage, high-energy varistor disk having electrodes disposed about its facing surfaces and a self-compressing spring clip with spring arms disposed about the varistor to provide the compressive force necessary to maintain good electrical contact between the electrodes and the varistor. The arrester includes terminals for electrically interconnecting the electrodes with the electrical apparatus being protected by the arrester. The arrester further includes a dielectric coating substantially enveloping the varistor, the spring clip and electrodes. The arrester requires no other housing. The spring arms may be made in a variety of configurations and shapes and may be interlaced with adjacent spring clip and varistor subassemblies so as to form three-phase or other multi-pole arresters.

Abstract: A terminal bushing having integral overvoltage and fault current protection includes an insulator having an upper and a lower chamber. Nonlinear resistors are disposed in the upper chamber between a top terminal and an intermediate terminal which are mounted on the insulator. The top terminal, the nonlinear resistors and the intermediate terminal form a first current path through the bushing. The bushing also includes a pair of mounting arms which support a current limiting dropout fuseholder. The fuseholder is disposed in series between the top terminal and a bushing stud which is retained in the lower chamber of the bushing body. A second current path through the bushing is thus formed by the top terminal, the fuseholder and the bushing stud.

Abstract: An apparatus for magnetic annealing of amorphous metal alloy cores. The apparatus includes a fluidized bed for heating the core, a conveyor for transporting the core and immersing the core in the fluidized bed and at least one winding for applying a magnetic field to the core. The apparatus can include a chill bath and/or a second fluidized bed for cooling the core. A chamber can be provided between the two fluidized beds for slow cooling the core by convection and radiation prior to cooling the core at a faster rate in the second fluidized bed.

Abstract: A method of heat treating an amorphous metal alloy by immersing the alloy in a fluidized bed to heat the alloy to a temperature below its recrystallization temperature. The alloy is maintained in the fluidized bed for a time sufficient to reduce internal stresses While minimizing crystal growth and nucleation of crystallites in the alloy. Then, the alloy is removed from the fluidized bed and cooled. A magnetic field can be applied to the alloy before, during or after heating the alloy in the fluidized bed. The magnetic field is applied for a time sufficient to achieve substantial magnetic domain alignment while minimizing crystal growth and nucleation of crystallites in the alloy. The cooling step is effective to maintain the magnetic domain alignment in the alloy. The cooling step can be performed with a chill bath or a fluidized bed which is cooled by a circulating gas such as nitrogen or air. The alloy can be slowly cooled by convection and radiation after it is removed from the first fluidized bed.

Abstract: A transformer core of non-circular cross-section, preferably rectilinear, is formed by successively wrapping individual packets of core strips around a stationary mandrel of non-circular cross-section. Each packet is wrapped by a pair of yieldably biased rollers which follow the contour of the mandrel. As the packet is being wrapped, pressure pads are extended to hold the packet against the mandrel. The pressure pads are momentarily retracted to accommodate return movement of the roller wipers to receive a subsequent packet. The ends of the packet form a joint at the top of the mandrel. The positions of successive packets can be changed to vary the location of the joint in order to form a desired joint pattern.

Abstract: A method of heat treating an amorphous metal alloy by immersing the alloy in a fluidized bed to heat the alloy to a temperature below its recrystallization temperature. The alloy is maintained in the fluidized bed for a time sufficient to reduce internal stresses while minimizing crystal growth and nucleation of crystallites in the alloy. Then, the alloy is removed from the fluidized bed and cooled. A magnetic field can be applied to the alloy before, during or after heating the alloy in the fluidized bed. The magnetic field is applied for a time sufficient to achieve substantial magnetic domain alignment while minimizing crystal growth and nucleation of crystallites in the alloy. The cooling step is effective to maintain the magnetic domain alignment in the alloy. The cooling step can be performed with a chill bath or a fluidized bed which is cooled by a circulating gas such as nitrogen or air. The alloy can be slowly cooled by convection and radiation after it is removed from the first fluidized bed.

Abstract: 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.

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: Non-linear resistors especially suitable for assembling into a stack are disclosed herein along with the stack and its method of assembly. Each resistor has opposite end surfaces to which a certain electrically conductive bonding substance, specifically solder, will adhere and an outer circumferential side surface extending between the end surfaces. The entire side surface of each wafer is covered with a coating layer formed from a dielectric composition to which the specific bonding substance will not adhere. This composition is also one which is able to withstand coming into contact with the bonding substance when the latter is in a liquid state, that is, it is able to withstand the temperature of molten solder when solder is used as the bonding substance and it must also be able to withstand the expected voltage and current levels across the wafer without any adverse effects.