Abstract: The present invention features a method and an apparatus for distributing electrical power from a power source to a distribution transformer, using at least one hot-phase conductor, a neutral conductor and an independent ground conductor. The neutral conductor is connected to the ground conductor at only one point in the distribution system, preferably at or near the power source. Normal imbalance current flows only in the neutral conductor. Return current flow in the earth is eliminated by the single point neutral-to-ground connection. Magnetic field (MF) generation in this power distribution system is thus reduced and stray voltage problems eliminated. In addition, high-impedance faults are easily detected because the only current ever flowing in the ground conductor is fault current. A method is also described for converting existing power distribution systems to the independent ground topology of the present invention.

Abstract: A high-tension transformer incorporates a protection module (35) housed in a space defined between the body (11) of the high-tension transformer (10) and its cover (14), with plug-in connectors (36, 36') to be fitted between the body (11) and the module. In particular, the invention is suitable for transformers employed in discharge-type tubular lighting fixtures used for neon signs.

Abstract: An electric device, such as a transformer, has a tank and an arrester for protection against high voltage surges, the arrester being grounded to a wall of the tank. A switch is mounted in the tank wall for enabling the ground connection to be disconnected from outside the tank. The switch includes a shaft extending slidably through an opening in the tank wall. A gripping handle is mounted on an outer end of the shaft, and a spring washer is mounted on an inner end of the shaft. The spring washer is electrically connected to a discharge side of the arrester and is movable toward the wall and into electrically conductive relationship therewith in response to sliding of the shaft. By sliding the shaft in a direction moving the washer away from the wall, the electrical connection is broken. The handle is threadedly mounted to the shaft to be reversible between a first position holding the shaft in its switch closed position, and a second position for enabling the shaft to be slid to its switch open position.

Abstract: A gas-insulated switch for a distribution transformer and its associated electrical connections are located within a tank containing insulating and cooling oil for the transformer.

Abstract: An electrical energy-transforming equipment comprises a transformer arranged within a cubicle, a current transformer and a potential transformer both connected to the transformer. The transformer, the current transformer and the potential transformer are molded in one piece. In another form of the electrical energy-transforming equipment, a transformer for distributing electric power, which is molded with an insulating material, such as a synthetic resin or a synthetic rubber, is molded in one piece with a current transformer and a potential transformer both connected thereto, with an insulating material, such as a synthetic resin or a synthetic rubber. The electrical energy-transforming equipment may further comprise a breaker also molded in one piece with the rest thereof, with the insulating material.

Abstract: A battery pack (10) includes at least one battery cell (16) and a current interrupt device (18) adapted to protect said cells from damage during charging or discharge. The battery pack (10) is further adapted to be recharged at extremely fast recharge rates via the use of a bypass switch (20) which allows current to be diverted around current interrupt device (18) during recharge. The bypass switch (20) is controlled by a control circuit (22) which provides a control signal and response to sensing a charge current.

Abstract: A ground fault detection circuit monitors an interlock control circuit for use with a machine or process control system. The interlock control system utilizes electromechanical relays with hard contacts. The interlock control system will disable operation of the machine or process if any ground fault condition exists in the interlock control circuit. A ground condition in the machine or process control circuits is permissible. The system uses a redundant circuit path to verify the integrity of the components in the interlock control system. The control system includes an ungrounded isolation transformer for supplying power to separate monitoring relays interposed between each leg of the transformer and ground. The contacts of these relays are series connected with emergency-stop (e-stop) switches to energize interposing control relays. The outputs of the interposing relays are used to energize the final control relay that controls the operation of the machine or process.

Abstract: A magnetic coil assembly with a connector arrangement which prevents explosion or other accident due to the mismatch of voltage rating between a surge absorber and a magnetic coil, allows only the surge absorber to be changed easily if it has been damaged, and ensures ease of automatically assembling the surge absorber into the magnetic coil assembly. The magnetic coil assembly includes a coil spool, a winding wound around the coil spool, and coil terminals mounted on the coil spool and electrically connected with the winding. The surge absorber is connected mechanically and removably with the coil spool or coil terminals, using connectors that may uniquely relate to the ratings of the absorber and coil, and the absorber terminals of the surge absorber are brought into contact with, and therefore are electrically connected with, the coil terminals.

Abstract: A low voltage power supply and distribution center comprises a housing (12) having three internal compartments including: a high voltage compartment (17), a low voltage distribution compartment (19), and a transformer compartment (21). The housing (12) is designed for surface or recessed mounting on or in a wall or ceiling. For recessed mounting, with the housing (12) surrounded with 20 cm (8 inches) of insulation, the maximum surface temperature of the housing is less than 90.degree. C. The three compartments (17,19,21) are formed by a removable power tray (15) having a torodial transformer (132) mounted thereon. The low voltage compartment (19) comprises a fuse panel (150) for mounting a plurality of plug-in fuses (153) from which the low voltage power is distributed. The high voltage compartment (17) comprises a switch or a dimmer (131) in a high voltage line between the transformer (132) and the incoming high voltage line, or the dimmer or switch may be remotely installed on a wall.

Abstract: A mini-transformer features an iron or ferrite core (2) and primary and secondary windings (3, 4). Portions of the windings (3, 4) which extend beyond the iron or ferrite core (2) are covered on both sides with a thermoplastic material forming a lid (6, 7). The two lids or end bells (6, 7) are combined into one piece by means of first bars (12), which extend through the hollow spaces (9) between the windings (3, 4) and the iron or ferrite core (2) and fill them, and that the laminated iron or ferrite core (2) is fixed in itself by second bars (14) connecting the two lids (6, 7).

Abstract: A test system having an improved physical layout and electrical design allows the 1/f noise of metal interconnects to be measured at levels close to that of Johnson or thermal noise. A detailed description of examples of operation of the test system provides evidence of the effectiveness of the test system in minimizing system noise to a level significantly lower than Johnson noise. This permits quantitative measurment of the noise contribution attributable to variations in cross-sectional area of connections for various applications and for qualitative prediction of electromigration lifetimes of metal films, particularly aluminum, having different microstructures. The test system includes an enclosure which includes several nested groups of housings including a sample oven within a device under test box which is, in turn, contained within the system enclosure.

Abstract: A current limiting method and apparatus for preventing fault overload in a utility power transmission system employs a high power, superconducting coil based pulse transformer for saturating the core of the utility power transformer thereby limiting its current carrying capacity. The utility transformer core is biased to a disadvantageous portion of its B-H curve. A fault condition is detected and as a result the superconducting coil is quenched thereby sending a high energy pulse of current into the utility transformer magnetic core. The core, while heating, does not exceed its capability to maintain a stable thermal condition while at the same time limiting the current being transformed from its input to output lines, until a transformer circuit breaker activates.

Abstract: A protective relay communication interface includes a transformer having primary windings arranged as, at least two, sets of opposed windings. The interface is connected to a local relay sensing a current at that point on a power line to be protected. The interface is also connected to a communication link to a remote relay sensing the current at a remote position on the power line. It is by this communication link that signals representative of the sensed currents are transmitted from each relay to the other. A local signal from the local relay is passed through part of, but not all of, the primary windings inducing a corresponding signal in the secondary windings of the transformer which is transmitted to the remote relay via the communications link. A received remote signal from the remote relay is passed via at least two mutually opposed sets of the primary windings to the local relay.

Abstract: A transformer bobbin is provided comprising a frame of approximately a rectangular shape, a first wall arranged on one end of the frame, a second wall arranged on the other end of the frame, and a center wall arranged between the first wall and the second wall. The frame, the first wall, and the center wall constitute in combination a primary winding section. The frame, the center wall, and the second wall constitute in combination a secondary winding section. In particular, the primary winding section has a container case detachably mounted thereto for selective assignment for use. Also, the container is arranged for accommodating a current disconnecting means for deenergizing a transformer circuit when the coil temperature increases up to a limit level.

Abstract: A circuit arrangement having the function of preventing over-voltage damage which is structured by special copper foil or conductive wires and applies the burst absorption principle to form a short circuit from the input end and the output end of a circuit when the circuit is subject to an over-voltage or a transient electrical strike, so as to protect the electronic elements within the area of the circuit. The method can be put into application in a transformer, a switching power supply, an electronic computer, a solid-state relay and other similar electronic equipment. The arrangement of the present invention has undergone a number of high voltage and electrical striking tests with more than satisfactory results and is suitable for use in industries.

Abstract: A fuse housing for an oil-cooled transformer that uses a stopper to prevent oil from escaping the transformer tank as the fuse and fuse holder are removed. During normal operation, the stopper is held in an open position by the fuse holder. When the fuse and fuse holder are removed, the stopper closes and seals the upper end of the holder, preventing oil from draining through the upper portion of the fuse housing and escaping from the transformer tank.

Abstract: A polyphase electric power distribution system is protected from the effects of geomagnetic storms by countering the difference of potential between spaced grounding points in the system, and or by altering the magnetic circuits of transformers in the system to reduce half-cycle saturation and associated high peak currents.

Abstract: The disclosure is directed to a transformer circuit apparatus which receives an input signal and generates an output signal representative of the input signal. For example, the input signal may be an AC current, and the output signal to be generated may be a voltage that is proportional to the current. A transformer is provided, and has a core, a primary winding for receiving the input signal, a sense winding, and a feedback winding. A first circuit is coupled to the sense winding, and is responsive to the magnetic flux sensed by the sensed winding, for applying a signal to the feedback winding that tends to reduce the flux sensed by the sense winding. A feedback circuit is provided, and includes a low-pass filter, for feeding back a signal that depends on the output signal to the first circuit means. A circuit is provided for determining the presence of input signal offsets, and for generating offset indication signals in response thereto.

Abstract: A polyphase electric power distribution system is protected from the effects of geomagnetic storms by countering the difference of potential between spaced grounding points in the system, and or by altering the magnetic circuits of transformers in the system to reduce half-cycle saturation and associated high peak currents.

Abstract: An electrical recloser apparatus includes a tank (10) having bottom, top and side walls (18, 22, 16) which define an interior, sealed space (14), and a current interrupter (44) disposed within the sealed space (14) and including a pair of relatively movable contacts (46, 48) which are movable between a closed, current-carrying position and an open, current-interrupting position. A control assembly (30) is provided for electronically controlling the opening and closing of the contacts (46, 48), the control assembly (30) initiating operation of the contact moving means (58) to move the contacts (46, 48) to the open position in response to a fault current sensed by a sensing means (66), and initiating operation of the contact moving means (58) to move the contacts (46, 48) to the closed position after each one of a predetermined number of opening operations.

Abstract: Current transformer mounting mechanism which mounts a current transformer having a core on a circuit breaker to diminish impact caused by switching operation comprising: at least one substantially U-shaped fitting board having curved portions at both ends thereof; at least one setscrew for mounting said fitting board to the core of the current transformer; and a current transformer mounting portion having opposing walls, each wall being provided with a shoulder where the fitting board being fixed; the current transformer being mounted to the current transformer mounting portion by inserting the fitting board to the current transformer mounting portion. The fitting board is preferably provided with embossed tabs at curved portions thereof.

Abstract: A two-stage gapped low voltage surge arrester for dissipating transformer secondary side current surges includes an arc strap in series with a resistive grommet. The combination is mounted on the grounded transformer housing adjacent a line potential bushing such that a first spark gap is formed between the bushing stud and arc strap. The resistive grommet is grounded to the transformer ground pad by metallic fasteners such that a second spark gap is formed in parallel with the resistive grommet. Surges entering the transformer secondary winding of sufficient magnitude induce the first spark gap to flash over, shunting potentially damaging currents outside the transformer through the arc strap and resistive grommet. At even higher currents, the voltage across the resistive grommet exceeds the flash over voltage of the second spark gap and shunts the surge around the resistive grommet.

Abstract: The reset circuit of a fault indicator is coupled to a transformer secondary winding by a cable having an elongated conductor and a resistance close to the secondary winding. The resistance is capable of withstanding a minimum transient impulse of 10 kv.

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: A 60 VA transformer is described. A recycling circuit breaker mounted on and connected in series with the secondary winding of the transformer preserves the integrity of the transformer and permits its continued use after a short circuit. A thermal fuse mounted on and connected in series with the primary winding provides short circuit protection in the event the circuit breaker fails in a closed position. Achievement of this end is attained by decoupling the transformer windings to reduce short circuit, secondary current flow. Decoupling is provided by spacing the transformer windings a distance of about 0.090 in. A controlled failure mode provides energy limiting protection for the secondary load circuit in the event of circuit breaker failure in the closed position. Controlled failure is provided by the use of secondary insulation which melts within one minute of a short circuit, permitting turns of the secondary winding to short and reduce current flow to eight amp. within the one minute period.

Abstract: An electrical transformer assembly characterized by a tank having opposite sides and a top access opening with a transformer structure movable into and out of the tank through the opening, the transformer structure including a coil and core assembly mounted within a support frame which frame has a top surface on which transformer components are mounted whereby the assembly of the transformer structure and transformer components are movable into or from the tank intact.

Abstract: This dual voltage transformer comprises a primary winding having a tap at a location intermediate its length, a first termination for connection to line voltage, and a second termination for connection to ground. When the transformer is to be operated at a relatively high voltage, the first termination is connected through a dual voltage switch to line voltage; and when the transformer is to be operated at a relatively low voltage, the tap is connected through said switch to line voltage. First varistor means is connected across the primary winding between said first and second terminations both when the transformer is operated at high voltage and at low voltage; and second varistor means having a lower breakover voltage than the first varistor means is connected between said tap and ground when the transformer is operated at low voltage.

Abstract: A high voltage shutdown circuit that tracks with brightness changes in the CRT. An ABL (automatic brightness level) signal is applied to adjust the conduction point of a latch transistor that is connected in a trigger arrangement with a zener diode and driven by a sensing winding on a high voltage transformer. The ABL voltage is applied to an inverting transistor and an opposite polarity potential is developed across a capacitor connected in series with the latch transistor. Because of the loading on the high voltage generating means, the voltage across the sensing winding does not accurately reflect the actual high voltage at the CRT and the circuit prevents premature high voltage shutdown under high beam current conditions.

Abstract: Electrical distribution apparatus, such as a pad-mounted electrical distribution transformer, including an electrically grounded tank, an electrical element in the tank, and a draw-out surge arrester assembly which extends into the tank. The draw-out surge arrester assembly includes a housing, and a draw-out device removably disposed in the housing. The draw-out device includes a fuse connected in series with the surge arrester, between the electrical element and grounded tank, with the fuse being sized to isolate the surge arrester from the electrical element, should the surge arrester fail to recover properly from a voltage surge.

Abstract: A face connected instrument transformer is disclosed having a plurality of transformation ratios comprised of two primary windings and a single secondary winding. Each primary winding is electrically connected to a pair of terminals disposed adjacent to opposite faces of the transformer housing for engaging contacts within a molded case circuit breaker housing. The transformation ratio of the instrument transformer is changed by removing the instrument transformer from the circuit breaker housing and inserting the opposite face.

Abstract: A dual voltage distribution transformer is protected by an internally installed, multi-rated surge arrester which is selectively connected with plural primary windings by a dual voltage switch such as to establish a high surge voltage protection level when the primary windings are connected in series by the switch and a correspondingly lower surge voltage protection level when the primary windings are connected in parallel by the switch.

Abstract: This distribution transformer is of the shell type and includes within its oil-filled tank a layer-type high voltage winding and a layer-type low voltage winding. The low voltage winding is divided into two sections with a grounded interconnection between said two sections. A metal oxide varistor device is mounted within the oil-filled tank and is connected between the high voltage terminal of the high voltage winding and ground. There is another connection between the mid-point of the varistor device and the mid-point of the high voltage winding. The varistor device so connected protects the high voltage winding against both voltage surges entering via its terminals and current surges entering via the terminals of the low voltage winding.

Abstract: A secondary circuit breaker for a distribution transformer characterized by electrical inductive apparatus within an oil-filled housing, and circuit interrupter for controlling current flow through said apparatus and comprising a releasable latch arm, trip means operable upon overload conditions to release the latch arm, a latch lever between the trip means and the latch arm, and a signal light circuit for activating a signal light when current through the circuit breaker exceeds a low signal overload value. That is less than the trip value.

Abstract: A primary power circuit breaker adapted to be immersed in the dielectric fluid for a transformer, the breaker including an arc interrupting assembly for extinguishing the arc produced on load break; a trip free mechanism responsive to primary, secondary or primary-secondary differential current signals and thermally responsive to fluid temperature, and an externally operable reset assembly for closing the circuit breaker.

Abstract: A spark arrestor for protecting a high intensity, gaseous discharge lamp, ballast and other circuit components against being damaged or destroyed by a large build up of voltage. The arrestor includes a multi-sided low dielectric disc with star-like conductive material on each side, the points of the star being opposite the mid-points of the sides. Terminals for connecting the spark arrestor across the secondary of the ballast, or other similar location, are connected to each of the star-like conductive materials. There is a non-conductive tubular shield around the disc to protect againt spreading of the spark, but the terminals extend from the ends of the shield for connection purposes.

Abstract: A high voltage transformer bushing having an inner conductor extending from a lower end to a point spaced from an upper end and having a side terminal at that point connected to a fuse link which is in turn connected to a high voltage line connector supported on the upper end of the bushing. A lightning arrester supported by and grounded to the transformer casing has an upper end spaced from the high voltage line connector to provide a spark gap.

Abstract: Zinc oxide varistor protective devices for vapor cooled transformers are integrally located in contact with the transformer coolant liquid to provide cooling capacity to the zinc oxide materials. The zinc oxide varistors are prevented from becoming electrically unstable by keeping the varistor operating temperature at or below the boiling point of the coolant.

Abstract: A ballast for operating a pair of fluorescent lamps includes an isolation transformer with a split secondary winding. A power capacitor is connected serially between the two sections of the secondary for reducing shock hazard associated with leakage current resulting when a high frequency emergency lighting circuit is operational and further, for minimizing transference of EMI from the lamp side of the ballast to the line side.

Abstract: An assembly of control handles for attachment to a distribution transformer containing a secondary circuit breaker. The assembly includes a stop plate which is located against the outside of the transformer tank. An operating handle and an overload control handle are positioned for rotation between projections on the stop plate. The operating handle is attached to the outer portion of an operating shaft which extends through an opening in the stop plate. The operating shaft also extends through a sealed bearing which prevents leakage of the fluid dielectric contained within the transformer tank. The inner portion of the operating shaft is connected to an operating arm which is attached to the circuit breaker opeating lever. The overload handle is attached to the outer portion of an overload shaft which extends through an opening in the stop plate and through a sealed bearing. The inner portion of the overload shaft is connected to an overload arm.

Abstract: An electrical apparatus, such as a distribution transformer, having heat pipe cooling. The transformer is provided with a cover in the form of a heat pipe with an evaporator section extending from the cover into the dielectric fluid of the transformer. The top of the cover forms the condenser section of the heat pipe.

Abstract: An electrical apparatus, such as a distribution transformer, provided with heat pipes for cooling. The apparatus is provided with attachment wells, either extending into the cooling fluid of the apparatus or secured along the outside wall of the apparatus. Heat pipes are provided which fit into the attachment wells, with the evaporator section of the heat pipe mounted in the wells. The condenser section of the heat pipe extends away from the apparatus. Thermally conductive grease is placed in the wells to minimize the temperature drop from the wells to the evaporator section of the heat pipe.

Abstract: a compensating reactor in a coupling capacitor potential device including a magnetic core with an inductive winding, the reactor providing inductive reactance cancelling capacitive reactance of the device, and a voltage limiting device connected across the compensating reactor which is a ceramic oxide non linear resistor. The reactor core can be a magnetic steel whose normal saturation level substantially exceeds the voltage at which the voltage limiter changes resistance.

Abstract: a coupling capacitor protection device with a voltage limiter connected across the tap capacitor feeding the induction transformer primary winding. The suppressor is a ceramic oxide nonlinear resistor changing from high to low resistance, thereby limiting the tap voltage to less than that at which the induction transformer core saturates in order to minimize ferroresonance in the circuit. Also, the limiter gives voltage protection to the tap capacitor circuit.