Abstract: A cooling apparatus for a medium voltage or high voltage switchgear includes an evaporator, a fluid conduit, and a condenser. The evaporator is configured to surround at least part of a current carrying contact. The fluid conduit fluidly connects the evaporator to the condenser. A section of the fluid conduit is formed within the evaporator and is electrically insulating and is configured such that fluid can contact an outer surface of the current carrying contact. The cooling apparatus is configured such that in use a working fluid in the evaporator is heated to a vapour state, and the vapour is transferred by the fluid conduit to the condenser. The vapour in the condenser is condensed to the working fluid. The condensed working fluid is passively returned via the fluid conduit to the evaporator.

Abstract: A method for manufacturing an electrodynamic acoustic transducer is disclosed. The electrodynamic acoustic transducer comprises a frame and/or a housing, a membrane, at least one coil and a magnet system, wherein the coil, in a cross sectional view with a coil axis being part of the sectional plane, comprises a plurality of conductive layers formed by an electrical conductor of the coil. The electrical conductor has a rectangular cross section in said cross sectional view, wherein a longer side of the rectangular cross section is substantially perpendicular to the loop axis. According to this method, a stack of conductive layers is made from the electrical conductor by stacking of separate pieces of the electrical conductor and electrically connecting the stacked separate pieces and/or by folding of the electrical conductor.

Abstract: A thermal management includes an inductor, a housing in thermal communication with the inductor, the housing defining a wall, and a conductor. The conductor has a greater heat transfer rate than the wall and is positioned within a groove and/or an aperture formed in the wall. The conductor is configured to transfer heat through the wall more efficiently than if the conductor were not present. A method of manufacturing a thermal management system includes forming a housing by additive manufacturing. The housing defines a wall having at least one of a groove and an aperture defined therein. The method includes positioning a conductor in at least one of the groove and the aperture. The conductor has a greater heat transfer rate than the wall. The method includes positioning an inductor into thermal communication with the housing.

Abstract: The present invention provides an electromagnetic apparatus with heat sink structure, comprising: metal housing, the metal housing further comprises the upper housing and the lower housing to fix the components of the electromagnetic apparatus and store the energy of the electromagnetic apparatus during operation; the electrical coil is mounted on the coil shelf and is provided with numbers of primary windings and secondary windings; the heat conductive tube is arranged in the gap of the windings for conducting the heat generated by the electrical coil to the outside of the electromagnetic apparatus. Furthermore, the conducting wire is electrically coupled to the electrical coil and transmits the input voltage and output voltage during the operation of electromagnetic apparatus.

Abstract: Methods and devices producing time varying magnetic field have therapeutic uses. The device contains a coil made of insulated wires, an energy storage device, an energy source and a switch. The coil is flexibly attached in a case. The device has at least one blower for cooling the coil. The methods and devices can be used in for example in physiotherapy, neuropsychiatric therapy, aesthetic therapy, urology or urogynecology.

Abstract: A transformer assembly includes a housing, a core within an interior of the housing, and at least one winding positioned around the core. The at least one winding and the core are mounted to the housing with potting material. At least a portion of a fluid circuit is defined within at least one wall of the housing. The at least the portion of the fluid circuit is defined through an opening in the at least one wall of the housing in fluid communication with the interior of the housing. A transformer assembly includes a housing, a core within an interior of the housing, at least one winding positioned around the core, and a fluid circuit defined at least partially within at least one wall of the housing being configured such that heat is transferred to the fluid from at least one of the core and the at least one winding.

Abstract: A radio frequency module includes: a module substrate that includes a principal surface on which external-connection terminals are disposed; a power amplifier that is disposed on the principal surface of the module substrate and amplifies a radio frequency transmission signal; and a heat dissipator that dissipates heat of the power amplifier. The heat dissipator includes: a heat dissipation plate that covers a surface of the power amplifier which is opposite to a surface that faces the module substrate; and at least a first leg that extends from the heat dissipation portion toward the principal surface of the module substrate.

Abstract: A high capacity aluminum spot welding trans-gun includes a pair of opposed electrodes, a weld control that controls the operation of the trans-gun, and a transformer that regulates the voltage to the trans-gun having a primary input voltage and secondary output voltage. A liquid-cooled high voltage primary conductor electrically connects the weld control to the transformer primary input and a low voltage secondary conductor electrically connects the transformer secondary output to the welding gun to energize the opposed electrodes.

Abstract: A conductive winding assembly combining a bent conduction sheet member and a covering member is provided. The bent conduction sheet member has a channel. The covering member includes a connection part, a first lateral plate, a second lateral plate, and a hollow part. A first groove is arranged between the first lateral plate and the connection part. A second groove is arranged between the second lateral plate and the connection part. The bent conduction sheet member is inserted into the covering member through the first groove and the second groove, and the connection part is inserted into the channel. The bent conduction sheet member is partially accommodated within the hollow part, and the bent conduction sheet member is partially exposed outside the covering member through the hollow part.

Abstract: The disclosure relates to an amorphous transformer core including at least one transformer core disc with a plurality of layers of strip-like amorphous core material arranged concentrically around at least one winding window. At least one heat dissipating plate extends into an interior of the amorphous transformer core and is fed from there into at least one heat exchange region outside the amorphous transformer core. This can enhance dissipation of heat energy which is produced inside the amorphous transformer core.

Abstract: A magnetic component such as a transformer or inductor comprises one or more litz-wire windings and one or more metallic cooling tube windings. Each litz-wire winding is wound together with a corresponding single metallic cooling tube winding on a common bobbin to provide an indirectly-cooled magnetic component.

Abstract: An immersion cooled inductor includes an inductor at least partially submerged in cooling liquid and a localized boiling feature operable to instigate boiling of the cooling liquid prior to oversaturation.

Abstract: An air cooling system, method, apparatus and kit applied to lower transformer operating temperatures, such as governed by a tank or container of oil, allowing transformer components to run more efficiently at a lower temperature level, e.g., down from the hot level operating temperatures typical in stressed conventional devices. By lowering the operational levels to within or below the nominal operational temperature ranges for the equipment, and recovering heat generated during operation, several advantages are obtained.

Abstract: A pumped loop cooling system is provided to cool a hollow winding of a transformer utilizing a two phase vaporizable dielectric refrigerant. A liquid refrigerant pump circulates the refrigerant into a transformer and through a copper tube winding of the transformer where the refrigerant at least partially vaporizes in removing heat from the transformer. The refrigerant is then circulated to a condenser and then back to the pump.

Abstract: A method for cooling a transformer and transformer apparatuses are implemented. A transformer apparatus, according to one embodiment, comprises: a conduction cooled electrical transformer (240) mounted to a cold plate (252); and a heat pipe (262) for supplementing cooling of the transformer (240), the heat pipe (262) comprising a first end (303), a second end (305), and a sealed low pressure cavity containing an amount of a fluid (311), wherein the first end (303) of the heat pipe (262) is located in a hot region of the transformer (240), the second end (305) is maintained colder than the first end (303) by contact with the cold plate (252), and heat produced at the first end (303) by operation of the transformer (240) is moved to the second end (305) by a closed loop vapor cycle in the sealed low pressure cavity using the fluid (311) of the heat pipe (262).

Abstract: A pumped loop cooling system is provided to cool a hollow winding of a transformer utilizing a two phase vaporizable dielectric refrigerant. A liquid refrigerant pump circulates the refrigerant into a transformer and through a copper tube winding of the transformer where the refrigerant at least partially vaporizes in removing heat from the transformer. The refrigerant is then circulated to a condenser and then back to the pump.

Abstract: The invention relates to a winding element (200) for conducting current, forming a component of a coil winding (132, 133; 408, 409), especially of a (welding) transformer winding, comprising fixing means (205) for fixing the winding element (200) to a carrier component (402, 403, 404). The invention also relates to a transformer arrangement (100; 600), especially a welding transformer arrangement, comprising a primary winding (132; 408) and a secondary winding (133; 409), the primary winding (132; 408) and/or secondary winding (133; 409) comprising at least one winding element (200) according to the invention.

Abstract: The present invention relates to a novel structure of a transformer for a high-frequency switching-type direct-current (DC) rectifier, and particularly to an improved structure of a transformer applicable to a large-current low-voltage high-frequency switching-type rectifier, wherein the transformer is comprised of a ring-shaped iron core (made of materials such as dust core or nanometer crystalline silicon or amorphous silicone), which is provided with a primary side formed with winding(s) of copper wire(s), coupling with a secondary side that is formed with a newly-developed module or block, which replaces the secondary side that was constructed to provide output with copper wires or copper plate with wire wound thereon. A cooling water tube is arranged in the secondary-side module to remove heat with the water so as to maintain normal temperatures of the transformer in a pollution-free manner with reduced size and weight and easy assembling and reduced costs of the transformer.

Abstract: An air core inductor includes an inductor member formed in a plurality of coils. The inductor member includes a first end portion, a second end portion and a hollow core portion. The air core inductor also includes at least one stray flux inhibiting member provided on one of the first and second end portions of the inductor member. The stray flux inhibiting member blocks stray magnetic flux emanating from the air core inductor.

Abstract: A copper tube with copper end pieces for a water-cooled secondary winding of a welding transformer is an example of a brazed assembly having a potentially corrodible side, the water-cooled side, and a low-exposure side, the air side or dry side, of the joined pieces. By shaping contacting surfaces of the parts at the brazed joint it is useful to form a barrier, for example, between a special braze material required for the corrosive side and a conventional, easy to apply, braze material for use on the air side of the joint.

Abstract: In one aspect, the present invention is a cooling assembly for an electrical component. The assembly includes a non-magnetic, thermally conducting spreader substrate, and at least one serpentine cooling tube disposed on and in thermal contact with the thermally conducting spreader substrate so that said substrate is cooled when the one or more serpentine cooling tubes are operating.

Abstract: A coil apparatus is described that incorporates two or more conductors, wound in parallel, following the same path, in intimate physical contact throughout the path but electrically isolated. The current applied to each of the coils can be selected independently. The field generated by the coil, or force on the coil in a magnetic field, is proportional to the algebraic sum of the currents. The power applied to the coil is proportional to the sum of square of the currents. By independently selecting the appropriate current's to apply to each of the conductors, a desired field, or force, can be generated by the coil for any desired power applied to the coil. By judiciously selecting appropriate currents to apply to each of the conductors, a range of fields, or forces, may be selected for which a constant power may be applied to the coil. A constant power enables the coil to operate at a constant temperature.

Abstract: An induction heating system having a fluid cooling unit, a power source, an induction heating device, a controller, and an alarm system to place the system in a safe condition when an improper operating condition is detected. The induction heating system may have a flow switch to detect fluid flow through the system. The system may operate to secure power to the induction heating device when cooling flow is inadequate. Alternatively, the system may increase fluid flow to provide adequate cooling flow. The controller may have a visual indicator of inadequate flow or an improper power source operating condition.

Abstract: A directly cooled magnetic coil, particularly a gradient coil for a magnetic resonance apparatus, has the conductors forming the windings which are provided with an inner cooling channel for conducting a cooling fluid therethrough, and the conductors are fashioned as profiled segment conductors whose individual profiled segments surround a cooling tube. The cooling tube is composed of material that is not electrically conductive, or is only slightly electrically conductive, particularly a flexible plastic.

Abstract: A method and apparatus for inducing heat within a workpiece. A flexible fluid-cooled induction heating cable is used to produce a magnetic field to induce electric current in a workpiece. The induction heating cable has separate fluid and electrical connectors to separately couple cooling fluid and electric current to and from the induction heating cable. An induction heating system having a fluid cooling unit, a power source, and a flexible fluid-cooled induction heating cable having separate fluid and electrical connectors. An extension cable may be used to enable the flexible fluid-cooled induction heating cable to be used at a greater distance from the power source and the fluid cooling unit. An insulation blanket adapted for use with a specific size workpiece may be used with the flexible fluid-cooled induction heating cable.

Abstract: This invention relates to a method of cooling an immersed induction coil, such as an ionizing coil used in a vacuum processing chamber. The coil 10 may comprise a coiled hollow tube 11 through which coolant can flow when pumped by a pump 13. A valve 16 is provided so that air can be passed through the tube in either direction and the direction of flow is controlled by a controller 19, which acts on the valve 16. The rate of switching of the valve 16 can be determined by a process condition or by monitoring the temperature of the downstream coolant and/or the coil.

Abstract: An inductor for a computer power supply module is provided. The inductor includes a one-piece, single turn winding formed of a material for conducting heat and electrical current. The material having at least about five times the amount of electrically conductive material necessary for conducting electrical current.

Abstract: A fluid cooled electric conductor for induction heating of a workpiece includes a flexible conductor which is enclosed within an insulating tube. The conductor is supported within the tube so as to be surrounded by a fluid conducting space or spaces. A support arrangement supports the tube. Temperature sensors adjust the heating process by, for example, operating variable-length holders that support the tube in a spaced relationship with a workpiece.

Abstract: A high frequency water cooled transformer for coupling a power source to an induction heating coil and which serves to convert the output of the power source into values appropriate for the induction heating coil, and to match the impedance of the power source with the impedance of the heating coil for maximum power transfer efficiency. The primary of the transformer is adapted to be connected to the power source and the secondary is adapted to be connected to the induction heating coil. The transformer includes a secondary formed of two parallel self-supporting elongated open-ended hollow electrically conductive cylindrical members. A pair of electrically conductive terminal blocks are respectively mounted on one of the ends of the cylinders and electrically connected to the cylinders. The primary winding is wound longitudinally through the two secondary cylinders, and the ends of the primary winding are connected to appropriate terminal pins.

Abstract: A magnetic core includes a body made of polycrystalline ceramic and at least one localized gap made of a composite magnetic material. The gap may be preferably fixedly joined to the body by bonding or molding. The magnetic core has applications in inductors or transformers. The inductor preferably has a coil located on the body, which coil is preferably made of multistranded enameled wires.

Abstract: Described is a low-loss induction coil for heating and/or melting metallic materials, the coil having windings formed by lengths of hollow tubing carrying a fluid coolant. In the central zone of the induction coil, the current is carried by hollow conductors made of copper which at the same time form the hollow tubing. Fitted at least in the windings at one end of the coil is a current-carrying element in the form of at least one braid whose individual conductors are insulated from each other, while remaining windings are designed as hollow conductors connected to the current-carrying element. The use of braids as the current carrier leads, at the end of the coil, to a reduction in eddy-current losses caused by transverse magnetic fields, while the use of hollow conductors in the rest of the coil results in the mean distance between the current flux and the metallic material being heated being kept at the minimum and losses due to this distance thus kept low.

Abstract: A high frequency water cooled transformer for coupling a power source to an induction heating coil and which serves to convert the output of the power source into values appropriate for the induction heating coil, and to match the impedance of the power source with the impedance of the heating coil for maximum power transfer efficiency. The primary of the transformer is adapted to be connected to the power source and the secondary is adapted to be connected to the induction heating coil. The transformer includes a secondary formed of two parallel self-supporting elongated open-ended electrically conductive cylindrical members which are separated and insulated from one another. A pair of electrically conductive terminal blocks are respectively mounted on one of the ends of the cylinders and electrically connected to the cylinders. The primary winding is wound longitudinally through the two secondary cylinders, and the ends of the primary are connected to appropriate terminal pins.

Abstract: The invention relates to a liquid-cooled valve reactor, in particular for a high-voltage DC transmission installation, including a reactor core (2) and a reactor coil (4), the reactor coil (4) including a primary winding (24), which comprises two cooled winding sections (30, 32), and a secondary winding (26), and the reactor core (2) being provided with a plastic jacket (14). According to the invention, the reactor core (2) is provided with a clamping frame (56) which has on its free surfaces (58) in each case a heat dissipator (60), a liquid-cooled secondary resistor (28) is provided, which is connected electrically in parallel to the secondary winding (26), and the encapsulated reactor core (2) and the reactor coil (4) are mounted on a baseplate (6). The result is an intensively cooled valve reactor.

Abstract: An improved narrow profile transformer and method of making is disclosed comprising a primary winding and a secondary winding with the secondary winding being interleaved with the primary winding. The primary and secondary windings are spiral winding with all portions of the primary and secondary windings intersecting a geometric plane extending through the narrow profile transformer. The primary and secondary windings of the narrow profile transformer may be encapsulated within a polymeric material.

Abstract: Electrically conductive tubing for realizing induction coils having improved efficiencies comprises an outer peripheral portion of conductive material defined by a plurality of side walls and a single hollow passageway. Each side wall has an inner and outer surface. At least one side wall has a curved outer surface. The hollow passageway is defined by the inner surfaces and can be either centered within the tubing or spaced apart from the center of the tubing. The present invention also defines an induction coil and an induction furnace having an induction coil which utilizes such tubing. The curved outer surface has a radius of curvature which is defined substantially by a function of the tubing width in the axial direction, and spacing between turns of the induction coil. The cross section of the outer surface of the outer peripheral portion of the tubing taken along a transverse axis of the tubing defines a geometric figure.

Abstract: A pancake-type transformer particularly suited for connection to an inductor for inductively heating crankshafts is comprised of a single turn secondary defined by a plurality of generally U-shaped tubular conductors interleaved between the turns of a tubular, multiturn primary conductor having opposite ends connectable across a source of power. The conductors of the secondary have opposite ends each interconnected with a corresponding one of a pair of terminal blocks connected to a tubular inductor. The terminal blocks are outwardly adjacent the primary and secondary conductor portions at one end of the transformer and include corresponding current collectors which extend inwardly across the opposite sides of the conductor portions at the one end of the transformer. Coolant for flow through the secondary conductors is communicated with the opposite ends thereof through coolant passageways in the current collectors.

Abstract: A clamp assembly includes a yoke having a rectangular configuration and circumscribes a rectangular space, and a pair of spaced electrically conductive terminal bodies mounted in the rectangular space of the yoke. The terminal bodies are adapted to be connected to corresponding electrical terminals of an induction heating machine. A clamp pad is slidably mounted in the rectangular space of the yoke and is moveable vertically toward and away from the tops of the terminal bodies. An induction coil assembly including a hollow induction coil and a pair of spaced parallel elongated terminal bars is provided, with the terminal bars removably clamped between the clamp pad and the tops of the terminal bodies.

Abstract: A hollow electrical conductor coolable to extremely low temperatures is disclosed. The conductor is hollow and has a connection for the introduction of extremely cold gases in a liquid or gaseous state and an outlet for the gases. At least one hose element (5; 24) is arranged in the hollow conductor (1; 19; 22; 23) and is connected to a gas connection and provided with perforations (6) to allow the gas to pass out. The hollow conductor (1; 19; 22; 23) is useful as an induction coil for induction furnaces for heating, keeping hot or melting metallic material. The external diameter of the hose element (5; 24) is smaller than the internal diameter of the hollow conductor (1; 19; 22; 23). The hollow conductor has passages (6a) in the wall to allow the gas to pass out and is fitted with a jacket (8) which provides an annular clearance to the hollow conductor and the gas emerging from the hollow conductor (1; 19; 22; 23) is collected and carried away.

Abstract: Method for fabricating a laminated coil conductor for a high current coil which includes wrapping a layer of insulation around a rotatable shaped mandrel and then winding a plurality of copper sheets over the insulation as the mandrel is rotated. Solder is interposed between the copper sheets and between coolant tubes positioned on each end of each coil conductor. The assemblage is then removed from the mandrel and raised to a temperature to bond the copper sheets and coolant tubes together. The assemblage is then placed in a structural box and a plastic is injected into the box to fill any voids between the coil conductor and the box.An assembly of a plurality of coil conductors arranged in a high current coil according to the method is illustrated.

Abstract: There is disclosed a current limiting electrical reactor that efficiently uses space. The reactor includes a supporting core with a circular periphery where the conductor is wound about the periphery of the coil in a convoluted spiral that spirals laterally out from the periphery of the core over itself, and lies in a radial plane passing through the core. A first terminal, adapted for electrical connection, is positioned at the beginning of the innermost turn of the conductor. A second terminal, also adapted for electrical connection, is positioned at the end of the outermost turn of the electrical conductor. Insulation is provided between adjacent turns of the conductor. This reactor configuration provides an electrical path along the conductor between the first and second terminals having a current limiting reactance.

Abstract: Method for fabricating a laminated coil conductor for a high current coil which includes wrapping a layer of insulation around a rotatable shaped mandrel and then winding a plurality of copper sheets over the insulation as the mandrel is rotated. Solder is interposed between the copper sheets and between coolant tubes positioned on each end of each coil conductor. The assemblage is then removed from the mandrel and raised to a temperature to bond the copper sheets and coolant tubes together. The assemblage is then placed in a structural box and a plastic is injected into the box to fill any voids between the coil conductor and the box.

Abstract: The invention relates to a cooling device for circuit configurations in which high electrical energies are converted and specifically for electrical matching circuits with which the impedance of a plasma path is matched to a high frequency generator. Herein one or several coils are provided with a water cooling system in such a way that the cooling water is completely separated from the electromagnetic fields through metallic material. These coils consist of two tubes slid one into the other, wherein the cooling water is fed and drawn through the internal tube and between the two tubes so that it is completely within the field-free region.

Abstract: A cryogenically coolable inductive coil including: a multicomponent conductor comprising a plurality of components, each component including a cable of conductive material having a longitudinal axis about which the cable is twisted, the cable being wrapped helically and being compacted, after wrapping, to minimize voids in the cable and to give the component a polygonal profile, the components being disposed parallel, and adjacent, to one another with mutually facing sides of adjacent components being in contact with one another; and an electrical insulating and support structure at least partially surrounding the conductor for supporting stresses induced in the conductor due to magnetic fields created by the flow of current through the conductor, the conductor and the structure being wound to form the coil.

Abstract: A cryogenically coolable inductive coil including: a multicomponent conductor comprising a plurality of components, each component including a cable of conductive material having a longitudinal axis about which the cable is twisted, the cable being wrapped helically and being compacted, after wrapping, to minimize voids in the cable and to give the component a polygonal profile, the components being disposed parallel, and adjacent, to one another with mutually facing sides of adjacent components being in contact with one another; and an electrical insulating and support structure at least partially surrounding the conductor for supporting stresses induced in the conductor due to magnetic fields created by the flow of current through the conductor, the conductor and the structure being wound to form the coil.

Abstract: A distribution transformer and a method of making same. The transformer has at least one closed magnetic circuit in the form of a hollow toroidal coil made from ferro-magnetic steel ribbon. An electric circuit is formed by a primary winding and a secondary winding each constituted by one or more sub-assemblies in the form of a double pancake. These double pancakes are juxtaposed and molded together in a solid insulating material to form a rigid insulating frame on which the magnetic circuit is wound to form one or more magnetic coils. The rigid insulating frame, which is constituted by the primary and secondary windings and the insulating material, also includes therein conduits capable of circulating a cooling fluid through the windings whereby to provide heat exchange to cool the assembly of the electrical and magnetic circuits.

Abstract: The torodial ring magnet is cooled by a gaseous cooling medium which is conducted through a first cooling circuit through the channels of the magnet coils of the magnet. The gaseous cooling medium exiting the magnet is cooled by a second liquid cooling medium in a second cooling circuit within an auxiliary cooler. Temperature sensors are provided to sense the temperature of the exiting gaseous cooling medium from the magnet sections to permit the opening or closing of a valve in the auxiliary cooler to cause the gaseous coolant to be cooled or not by the liquid cooling medium.

Abstract: Improved electric induction heating apparatus wherein the coil has two or more windings of special low loss conductor with such windings electrically connected in parallel. The two or more windings can be wound simultaneously one on top of the other and/or disposed radially one outside of the other. The coil windings embedded in a rigid set resinous material thus providing a rigid cylindrical unit. At least one of the coil windings has the low loss conductor around a tube the latter providing a fluid flow path for circulatig cooling fluid therethrough by at least one of current balancing transformers, transposition of the windings, and appropriately choosing the number of turns of each coil layer. A split ring bus can be used at the ends of the coils to connect the windings in parallel and laminated steel yokes can be disposed about the coil.

Abstract: A coil designed for providing a highly uniform magnetic field suitable for use in nuclear magnetic resonance computer-aided tomography is provided with preheating apparatus which uses forced circulation of warmed liquid along the path normally circulated with the cooling liquid whereby there are simulated the normal operating coil heating conditions even when the coil is not operating so that the start-up stabilization time can be shortened.

Abstract: A compact valve choke that is simple to manufacture, which can, however, ensure the qualities required for all operating modes, namely the needed dielectric strength and freedom from partial discharges between components that are at different voltages. This valve-choke is achieved by having: the choke windings arranged in a supporting frame in a self-supporting manner, in relation to one leg of the choke core; the choke windings potted on all sides, and the potted block supported in the supporting frame by means of fittings; the choke core consists of two generally circular-shaped cores and is secured in the supporting frame; and the choke coil includes two primary windings wound in two layers, with an outer first winding portion and a concentric inner second winding portion as well as, a core-potential center tap roughly in the center of the windings between the first winding portion and the second winding portion.

Abstract: A current transformer has a hollow tube made from an electrical conductor which is bent at its center so as to form a loop which functions as a primary winding and two parallel straight portions at the ends of the tube which function as leads for the primary winding. The tube has a longitudinally-extending fluid-carrying passageway for a dielectric fluid formed at its center. Both ends of the tube are open and communicate with the inside of a reservoir for a dielectric fluid. A longitudinally-extending electrically-insulating member is inserted into the fluid-carrying passageway of one of the straight portions of the tube so as to decrease the cross-sectional area of the passageway in that portion and increase its resistance to flow. The increase in flow resistance produces a temperature difference within the tube, promoting circulation of the dielectric fluid by convection.