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8169762 |
Relay with current transformer
Current transformer relays having dual functions as current transformers and electromechanical switches are described. The current transformer relay includes a relay coil and a conducting loop...
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8023572 |
Communication interface employing a differential circuit and method of use
A communication interface employing a differential circuit and method of use is disclosed. In one form, a circuit operable to communicate signals via a communication bus can include a differential...
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8013702 |
Versatile distribution transformer
A versatile distribution transformer having an electromagnetic transformer and a power electronic module is provided. A pocket having connectors electrically connected to at least one winding...
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7869167 |
Method and device for prevention and protection of electrical transformer against explosion and fire
The present invention relates to the system and method for protection, prevention and or detection of the explosion and or resulting fire in electrical transformers in advance, i.e before...
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7839610 |
Load driving device and electrical device using the same
A load driving device according to the present invention includes: a first current generation section generating a first current in accordance with a driving current of a load; a second current...
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7812615 |
Method and device for fault detection in transformers or power lines
A method for fault detection in a power transformer/autotransformer and/or interconnected power lines, which are within the zone protected by the differential protection, and particularly suitable...
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7738221 |
Transformer inrush current detector
A differential protection system for power transformers using Rogowski coils as current sensors can support an inrush current detection method based on sensing lows in the derivative of the sensed...
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7719803 |
***WITHDRAWN PATENT AS PER THE LATEST USPTO WITHDRAWN LIST***
Load driving device and electrical device using the same
A load driving device according to the present invention includes: a first current generation section generating a first current in accordance with a driving current of a load; a second current...
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7633737 |
Liquid immersed surge arrester
A liquid immersed surge arrester that protects electrical equipment includes a module assembly. The module assembly includes at least one varistor and a pre-impregnated composite around the at...
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7456601 |
System and method for starting a wound rotor motor
A system and method for starting and regulating a wound rotor motor especially during the period between inactivity and a speed determined by the voltage ratings of the drive system. In a first...
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7365451 |
Power converter
A power converter that can continue to operate after suffering a partial failure. The power converter includes multiple array transformers; normally-on switches connected respectively in series...
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7340355 |
Compensated current differential relaying method and system for protecting transformer
Disclosed is a compensated current differential relaying method and system for protecting a transformer more correctly by calculating and estimating an exciting current including a core-loss...
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7336046 |
Short-circuit detection in electric path connecting drive device and load
A control device controls a drive signal supplied from a drive device to a load apparatus along an electric path connecting the drive device and the load apparatus. The drive device receives a PWM...
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7294973 |
Discharge tube lighting apparatus, light source apparatus, and display apparatus
A discharge tube lighting apparatus is used to drive a plurality of discharge tubes. The apparatus includes a balance coil having a winding input end and a plurality of winding output ends to which...
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7196884 |
Apparatus and method for detecting the loss of a current transformer connection coupling a current differential relay to an element of a power system
Disclosed is an apparatus and method for detecting a loss of a current transformer connection coupling a protective relay to a power system element of a three-phase power system and providing a...
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6870719 |
Plausibility checking of current transformers in substations
The invention relates to a method, a computer program and a device (20) for the plausibility checking of current transformers (7) in an electrical switchgear assembly (1) and to a switchgear...
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6507184 |
Methods and apparatus for differential current measurement in a three-phase power system
A measure of the current through a first terminal of a device in a three-phase power system is obtained for each phase of the system. A measure of the current through a second terminal is also...
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6483680 |
Magnetizing inrush restraint method and relay for protection of power transformers
A method and relay for magnetizing inrush restraint in protective relays for power transformers. The method utilizes the phase angle relation between the fundamental component and the second...
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6356421 |
System for power transformer differential protection
Current transformer (CT) secondary currents for the windings of a power transformer are used to produce a differential current. An operating current value is obtained from the differential current...
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6247003 |
Current transformer saturation correction using artificial neural networks
A method and apparatus of correcting for saturation in a current transformer, which outputs a current measurement, is provided. A switching algorithm receives a value of the current measurement...
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5963404 |
Restricted earth fault protection for transformers using a directional element
The residual phase currents for each selected winding of a transformer are first determined and then summed to provide a value designated IX. The neutral current for the transformer is also...
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5949633 |
Fluorescent lamp drive system with transformer over-voltage protection circuit
A transformer over-voltage protection circuit shuts down a resonant inverter when high voltages occur at the output of a transformer. The high voltages can be caused by a broken or removed display...
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5949343 |
Supervisory apparatus for oil-filled electrical equipment
There is provided at least one pressure detector for detecting a change in pressure of an insulating medium, a vibration detector for detecting vibration of an oil-filled electric equipment, and a...
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5847910 |
Fault protection device in a transformer
A fault protection device incorporated in a transformer having a primary winding and at least two secondary windings connected to ground, and having a sensing coil to sense the fluxes generated by...
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5815387 |
Transformer protective apparatus having semiconductor and mechanical bypass means
A power converter protective apparatus for protecting an AC-DC converter against an excess fault current by preventing the fault current of a power system from flowing into the AC-DC converter. The...
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5808844 |
Current differential protection arrangement
A current differential protection arrangement for an electric power supply unit with a measured value pre-processing device and an analysis device that checks on the basis of a predefined...
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5790357 |
Differential current protection for a transformer
A differential current protective device for a transformer arranged in a multi-phase power supply system and having at least one star-connected winding arrangement with a grounded star point. The...
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5784233 |
Differential protection device of a power transformer
A preprocessing circuit receives signals representative of a current circulating in a primary winding and of a current circulating in a secondary winding of a transformer. The signals...
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5627712 |
Transformer differential relay
The reliability of transformer differential relays is enhanced by providing a method and apparatus which enable improved discrimination between transformer current differentials due to transformer...
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5568343 |
Circuit for protecting switching power source from overloads and shot circuits
A protective circuit is used in conjunction with a switching power source for protecting the latter from overload and from short circuits. It is detected whether the current at the primary winding...
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5513058 |
DC link circuit for an electronically commutated motor
A protective DC link circuit connecting a motor to a power supply. The motor has a stationary assembly and a rotatable assembly in magnetic coupling relation thereto and includes windings adapted...
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5319513 |
Harmonic monitor and protection module
A monitoring apparatus for a tuned harmonic filter is provided to prevent electrical system and filter damage. A tuned harmonic filter is provided in an electrical system to prevent overheating,...
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5241443 |
Transformer fault protection device
A transformer ground fault protector is provided and includes sensing means in the form of at least one conductive plate adjacent but spaced from the output of each secondary winding in a...
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5170308 |
Method and system of transformer protection and method and system of detecting a defective winding
A method and system of transformer protection in which parallel admittance currents indicative of the apparent excitation state of a transformer to be protected are evaluated from the transformer...
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5014153 |
Transformer differential relay
An apparatus for monitoring phased currents in a first winding and a second winding of a transformer and for disconnecting the transformer from a power source supplying the transformer when a...
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4843310 |
Electricity meter with arrangement for monitoring core saturation incidents
A device for use in connection with electricity meters incorporating current transformers is disclosed. The device detects saturation incidents of the magnetic cores of the transformers, thereby...
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4772978 |
Transformer protection system
In a transformer protection system, data of voltages and currents detected at individual terminals of a transformer connected to an electric power system are supplied to a computer. The computer...
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4745512 |
Remote protection of three phase distribution transformers
It is desirable to provide remote digital protection of distribution transformers. This specification discloses a protection system able to measure and compare increases in both negative and...
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4704653 |
Transformer differential relay with speed-up apparatus
A transformer differential relay which includes apparatus for speeding up the detection of a power transformer internal fault condition to initiate breaker action which interrupts current through...
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4661877 |
Transformer protective relay
A protective relay for a transformer issues a relay tripping command when the differential current that is the difference between currents in the primary and secondary windings of the transformer...
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4530025 |
Current ratio-differential relay
A current ratio-differential relay for protecting a power system comprises a logical circuit which provides the final output upon determination that the operating force signal is active and the...
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4502086 |
Differential protective relay
A differential protective relay for protecting devices on an ac electrical power system. The protected devices can include a transformer, a generator, or a station bus. The differential protective...
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4477854 |
Portective relay with second harmonic suppression
A relay adapted for protection of a transformer and capable of functioning with certainty upon occurrence of any internal fault in the transformer but not functioning in the case of an inrush...
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4360849 |
Power distribution system
A distribution substation including a transformer module and a feeder module. The transformer module including a tank, a transformer having primary and secondary windings immersed in insulating oil...
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4236187 |
Power supply voltage stabilizer
A power supply voltage stabilizer comprising a transformer, of which the primary winding is connected to a switching means for controlling power supply to the primary winding. An oscillator circuit...
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4204237 |
Solid state transformer differential relay
A transformer differential relay monitors the current flowing through the primary and secondary windings of a power transformer and disconnects the transformer from a power source feeding the...
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4175276 |
Transformer inrush current detector
To detect a d-c component of alternating current in the primary winding of an electric power transformer, a pair of current transducers are provided. Each current transducer has a saturable core...
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3974423 |
Differential current protective device
A differential current protective device comprising a responsive unit, current transformers feeding a polyphase bridge rectifier, a single-phase bridge rectifier connected to the secondary of a...
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3946280 |
Overload protection circuit
This invention refers to an overload protection circuit for an oscillatory circuit driving an electro-acoustic converter and more specifically concerns a circuit for automatically inhibiting the...
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3849705 |
FLUID-COOLED TRANSFORMER HAVING A TEMPERATURE RESPONSIVE INDICATING AND CONTROLLING DEVICE
Temperature responsive device suitable for use with air-cooled power transformers. The temperature responsive device indicates the temperature at a predetermined location within the transformer and...
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