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...Daniel Webster invented a "bull plow" to pull out tree stumps. It didn't catch on because it was huge and required four oxen to pull it!
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| Number | Title | Issue Date |
| RE41814 | Method and apparatus for providing selectable output voltages A transformer is provided along with a combination of bridging tap-changers to provide a wide range of selectable output voltages in discrete, relatively small voltage steps where the highest voltage is more than double the lowest output voltage. Relatively inexpens... | 10/12/2010 |
| 7444266 | Control system for a transformer or reactor A universal control and diagnostic system for a transformer that may be retrofit with existing control and tap-changer equipment, the system providing for remote monitoring and control of the equipment and for measuring various criteria associated with the tap-chang... | 10/28/2008 |
| 7362203 | Multi-tap microelectromechanical inductor An apparatus, system, method, and article for a multi-tap microelectromechanical inductor are described. The apparatus may include an inductor formed on a substrate, a switching mechanism contacting the inductor to vary inductance of said inductor; and a disconnect ... | 04/22/2008 |
| 7315231 | Electrical reactor assembly having center taps An electrical reactor assembly and method of assembly is disclosed. The reactor is formed from a combination of a magnetic T-core and a pair of magnetic L-cores. A plurality of comb-like separators is placed over a vertical portion of the T-core. A wire, with a rect... | 01/01/2008 |
| 7295095 | Electric component and method of producing the same In a push-pull switching circuit for a low-voltage, large current application, a decrease in resistance of a transformer and of its peripheral circuit is sought for. In view of this, a coil (2) is fixed at its terminal (T1) side, and is wound around a ... | 11/13/2007 |
| 7277000 | Inductor and transformer In an inductor having a core and first and second coils wound upon the core, the wire of the first coil and the wire of the second coil lie are wound so as to lie parallel to each other and contact the core. The winding starting position of the first coil is made to... | 10/02/2007 |
| 7233223 | Transformer winding A Winding for high voltage transformer having a predetermined number of spaced winding groups joined to form a single winding transformer, each spaced winding group being solenoid wound from a predetermined number of turns. A method of forming the winding and a tran... | 06/19/2007 |
| 7154364 | Electrical machine An electric machine comprises a core (10) of magnetic material and a first insulating layer (14) of a solid electrically insulating material surrounding the core. A high-voltage winding (17) in the form of an electric conductor is wound around a... | 12/26/2006 |
| 7148781 | Landscape lighting transformer having increased loading features A transformer for low-voltage applications such as landscape lighting, comprising a primary winding and a secondary winding inductively coupled to the primary winding, the primary winding adapted to be energized with a high voltage and the secondary winding adapted ... | 12/12/2006 |
| 7113068 | Winding structure of inductor used in power factor correction circuit A winding structure of an inductor used in a power factor correction circuit is provided. The winding structure includes a ring-shaped core with a gap, a first coil and a second coil wound around the core. The negative end of the first coil and the positive end of t... | 09/26/2006 |
| 7078997 | Transformer assembly, and power conversion apparatus and solar power generation apparatus using the same In a transformer assembly formed by using a plurality of transformers each formed by winding a primary coil and a secondary coil around a winding core, one terminal and the other terminal of the primary coil are arranged on opposite sides of the winding core, one te... | 07/18/2006 |
| 6856226 | Integrated transformer A transformer comprises a substrate comprising a semiconductor material, a first conductor over the substrate, a second conductor over the substrate, and a magnetic layer over the substrate. The first conductor defines a generally spiral-shaped signal path having at... | 02/15/2005 |
| 6794976 | HF transformer assembly having a higher leakage inductance boost winding A high frequency transformer for a welding-type device is provided. The transformer includes a pair of ferrite cores and a bobbin configured to receive and support the pair of ferrite cores. A primary winding assembly, as well as, a secondary winding assembly is pro... | 09/21/2004 |
| 6734772 | Method and apparatus for providing selectable output voltages A transformer is provided along with a combination of bridging tap-changers to provide a wide range of selectable output voltages in discrete, relatively small voltage steps where the highest voltage is more than double the lowest output voltage. Relatively inexpens... | 05/11/2004 |
| 6583703 | Electrical apparatus having an electromagnetic device operable at multiple inductance values An electrical apparatus and method for matching the input power source and output impedance of the electrical apparatus utilizes electromagnetic devices having two or more inductive windings, which may be connected in various series and/or parallel circui... | 06/24/2003 |
| 6175293 | Planar inductor A planar inductor has a spiral coil, insulating layers stacked on both surfaces of the spiral coil, and ferromagnetic layers stacked on the insulating layers, wherein each ferromagnetic layer has a saturation magnetization 4πMS of 10 kG or mor... | 01/16/2001 |
| 6137391 | Flux-controlled type variable transformer A flux-controlled variable transformer can control voltage at a high speed without using any voltage adjusting tap. The transformer has a first and second magnetic circuits. The first magnetic circuit is composed of a first and second U-cut cores (13 and ... | 10/24/2000 |
| 5815378 | Flyback transformer A flyback transformer has a high-voltage bobbin. The bobbin is provided with a focus-pack connection terminal in addition to electronic-component mounting terminals. The focus-pack connection terminal is connected to one of the electronic-component mounti... | 09/29/1998 |
| 5619176 | System for coupling external leads to a multitap transformer A coil assembly for use in an inductive apparatus, is comprised of a conductive material, either copper or aluminum, continuously wound around a circular or rectangular shape. At a predetermined number of turns, a terminal or tap is formed in the conducto... | 04/08/1997 |
| 5523674 | Step switch The invention relates to a load selector for step switches in step transformers with two movable selector contacts. A suitable vacuum switch is located downstream of the first movable selector contact to switch the load current and a suitable switch for s... | 06/04/1996 |
| 5516992 | Transformer tap changing and step switch assembly A cast-resin transformer has a transformer housing, a plurality of windings each having a plurality of taps, respective contacts connected to the taps and mounted on the housing in respective arrays which are all identical, and respective identical mounti... | 05/14/1996 |
| 5477113 | Apparatus for applying a variable voltage to an electric load An apparatus for applying a variable voltage to an electric load utilizes a transformer with several taps to provide different voltage levels for the load. The load is connected to alternate taps by a switching device, which is operated by a control devic... | 12/19/1995 |
| 5430426 | Transformer 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 tub... | 07/04/1995 |
| 5369388 | LTC compensating winding for parallel operation of transformers A winding configuration for a transformer equipped with a load tap changer which maintains an impedance balance when the transformer is connected in parallel with another transformer in the field. The winding configuration, from the core outward, consists... | 11/29/1994 |
| 5208433 | Inductive heating coil A cooling tube (T) is incorporated into each conductor (C1) of the coil. The current carried by this conductor is divided between the strands which are maintained in thermal contact with the tube even in transposition or twist areas in which the conductor... | 05/04/1993 |
| 5107200 | Load switch for a step transformer A switching system for a step transformer having at least two adjacent taps and a pair of terminals shiftable between the taps has a pair of fixed contacts normally connected to the terminals, a vacuum interrupter connected between the terminals and displ... | 04/21/1992 |
| 5057809 | Variable inductance RF coil assembly A variable inductance RF coil assembly including an air-core, high-voltage coil, a printed circuit board installed inside of the coil, the circuit board carrying a plurality of switch contacts corresponding in location and in number to the turns of the ai... | 10/15/1991 |
| 4864266 | High-voltage winding for core-form power transformers A high-voltage winding for core-form power transformers is disclosed that uses two different conductor configurations within a single coil to minimize eddy current losses. The winding includes a first elongated conductor bundle formed from a plurality of ... | 09/05/1989 |
| 4694140 | AC power supply The invention is directed to an AC power supply for portable welding machines or the like which employ a transformer of either single or multi-phase power wound around a cylindrical core. The core is constructed from a continuous length of steel alloy rib... | 09/15/1987 |
| 4694241 | Transformer tap changer One of a plurality of taps of at least one transformer is selected by choosing a predetermined plug to mate with a predetermined jack. The connection arrangement between each transformer and a corresponding jack is such that each pin of a respective jack ... | 09/15/1987 |
| 4663603 | Winding system for air-cooled transformers A winding system for gas-cooled transformers, comprising windings disposed around a core; and at least one insulation torus, consisting of an insulating mass, said torus having embedded therein electrodes electrically connected to an adjoining winding for... | 05/05/1987 |
| 4607211 | Method of correcting inaccurate instrumental potential transformer ratio To compensate for voltage ratio errors in a cascaded core instrument potential transformer, the coils of an outer coupling winding otherwise utilized to magnetically couple an adjacent pair of cores together are electrically connected into the primary win... | 08/19/1986 |
| 4588971 | Electric transformer with annular coil forms The transformer comprises a magnetic circuit (8) as well as, in the case of each phase, a high-voltage electric circuit (17) and a low-voltage electric circuit (18) both wound around at least one section of the magnetic circuit (8). The electric circuits ... | 05/13/1986 |
| 4533892 | Split structure type transformer A split structure type transformer has a core upper and lower split-up secondary windings and a primary winding which are wound about the core, a single tap winding having a plurality of tap winding parts and a plurality of tap terminals, and a single tap... | 08/06/1985 |
| 4520818 | High dielectric output circuit for electrosurgical power source A transformer circuit including a primary coil with first and second voltage divider segments arranged in phase with equal inductances and a plurality of taps on the second segment. A switch is used to selectably ground one of the taps for varying the vol... | 06/04/1985 |
| 4504811 | Cable operated tap changer for a three-phase transformer A three-phase transformer including tap changing apparatus for switching the turns ratio between the primary and secondary windings of a transformer. The tap changer comprises a cable operated mechanism for moving a movable contact carrier relative to thr... | 03/12/1985 |
| 4471334 | On-load tap-changing transformer An on-load tap-changing transformer in which its high-voltage winding is axially divided into parallel-connected halves, and an end conductor constituting part of the high-voltage winding is connected to the other terminal of each of the halves. A coarse ... | 09/11/1984 |
| 4412199 | Regulating winding connected in series with a main winding of a transformer The invention relates to a regulating winding for a transformer in which a plurality of helical current-carrying conductor loops are connected in series with each other, whereas a plurality of non-current-carrying helical potential control loops are provi... | 10/25/1983 |
| 4386333 | Universal electrical connection apparatus Different line-cord sets connect an electrical device to different supply voltages, assuring that the supply voltage matches the device. Each line-cord set has a uniquely keyed socket and a wall plug. A device receptacle receives the line-cord's keyed soc... | 05/31/1983 |
| 4329674 | High voltage transformer for AC-DC converter A converter transformer for an AC-DC converter is assembled by connecting three transformer units at an installment site. In the respective transformer units, first, second and third iron core legs are received in oil tanks. On the first and second core l... | 05/11/1982 |
