Matches 1 - 50 out of 209 1 2 3 4 5 >
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7589438 Source phase sensitive transfer method and apparatus  
A method and apparatus for transferring AC electrical power to a load from a first power source to a second power source provides for a time delay in the transfer to avoid problems associated with...
7480124 Detection of an AC input phase-loss on a multi-phase AC servo drive  
Systems and methods that detect a phase loss condition in a three-phase electrical power source are presented. The system includes a detection component that measures and/or monitors a magnitude...
7453674 Method for protecting an electric generator  
A method for protecting an electrical generator which includes providing an electrical generator which is normally synchronously operated with an electrical power grid; providing a synchronizing...
7403015 System for wireless monitoring of circuit breakers  
A system for monitoring a circuit breaker that includes a monitoring device in electronic communication with the circuit breaker and a receiving device located separately from the monitoring...
7355866 Method of detecting phase-loss state of three-phase power supply  
The disclosure relates to a method of detecting the phase-loss state of the three-phase power supply. When the phase-loss condition occurs in the input three-phase power supply of the power...
7352549 Method of automatically recognizing an electrical system  
The subject matter of the present invention is a method of automatically recognizing an electrical system by which both the voltage of an electrical system ( 2 ) and the phase angle between phases...
7319576 Apparatus and method for providing differential protection for a phase angle regulating transformer in a power system  
Provided is an apparatus and method for providing differential protection for a phase angle regulating transformer having a load side and a source side in a three-phase power system. The method...
7299143 Method and apparatus for improving operational reliability during a loss of a phase voltage  
The present invention is directed to a method and apparatus for improving operational reliability during a loss of a phase voltage (LOV) in a multi-phase power system, wherein a voltage...
7259947 Phase control switching device  
Respective contact terminals in respective arc-suppressing spaces of respective breakers are opened at a voltage zero point of any phase of three phases, simultaneously among the three phases. If...
7242563 Reverse phase control power switching circuit with overload protection  
In one embodiment of the invention, a reverse phase control power switching circuit for controlling the flow of current through a load from an AC source comprises a sensing bridge in series with...
7218015 Method of providing a constant AC voltage to a remote variable load  
To the end of providing a constant AC voltage to a variable load ( 1 ) which is arranged remote of a voltage source ( 3 ), a voltage drop over an electrical supply line ( 2 ) which connects the...
7126801 Polarity protection implemented with a MOSFET  
A polarity protection circuit contains a metal oxide semiconductor field effect transistor (FET) that pets its control voltage via an electrical connection from supply voltage lines and a...
7095598 Fault detection apparatus and method  
There is provided an apparatus for producing a trip signal to activate a circuit breaker in an alternating current power line, said apparatus comprising: a sensing circuit operable to sense values...
7095138 Controller for plural supplies driving single load  
A controller is disclosed for determining that the currents from the two AC power sources are correctly phased. Required circuitry can be disposed within a housing from which extend power cables...
6841761 Nominal voltage identification system for electric resistance  
U.S. Ser. No. 2002009312A cooking appliance having an electric resistance heater is connected to a multiple phase external power source and includes a system for compensating for whether the...
6661630 Distance relay for protection of transmission line having minimized reactance effect  
A distance relay for protection of a transmission line, which is capable of estimating apparent impedances with respect to faults on the transmission line involving fault resistances, more...
6639413 System and method for calibration of data in an electric power monitoring system  
The error compensating system and method is used in electric power monitoring systems, e.g. protective relays, and includes a test unit for applying a test signal to the front end of a data...
6493203 Phase control switch apparatus  
A phase control switch apparatus incorporating a phase-based break/make controller ( 80 A, 80 B, 80 C) for protecting a reactive load such as a transformer ( 10 ) from transient surge phenomena...
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...
6433527 Phase failure detector for multi-phase switching regulators  
The present invention offers a low cost, reliable, on chip implementation that takes advantage of the nature of the average current mode topology to detect phase failures within a multi-phase...
6396282 Process for testing the ground contact of parts of a networked system  
In a method for testing the ground contact of parts of a networked system in which data are sent and received via at least one line, at least one line at each part is connected via a resistance...
6313636 Method for determining switchgear-specific data at contacts in switchgear and/or operation-specific data in a network connected to the switchgear and apparatus for carrying out the method  
A method for determining switchgear-specific data at contacts in switchgear and/or operation-specific data in a network connected to the switchgear includes detecting a so-called contact...
6239959 Ground distance relay for AC power transmission line protection  
An improved reactance characteristic for an overall ground distance quadrilateral characteristic embodies a particular phase selector, possibly among a plurality of phase selectors and variables,...
6157552 Sub-harmonic detection and control system  
A distribution series capacitor control system is provided with a sub-harmonic detection module connected to an input signal and operable to detect the presence of at least two distinct types of...
6130531 Phase angle measurement method and system in electric power systems  
6101075 System for improving protective relay coordination with other protective elements in power system  
The system first identifies the existence of a fault involving ground using the phase angle difference between negative sequence and zero sequence current on the power line. Phase angle differences...
5995347 Method and apparatus for multi-function electronic motor protection  
A multi-function protection system (8) for protecting electrical equipment such as a screw compressor motor is shown having a housing (10, 20) mounting current sensing toroids (CT1, CT2, CT3) and...
5894174 Protection circuit and method for an electromagnetic interference suppression system  
The present invention relates to protection circuit and method for the EMI/RFI suppression system (2) of such a five-conductor electrical system in which the neutral conductor (N) is provided with...
5892645 Protection system for power receiving station  
A protection apparatus for a spot network substation has a plurality of receiving lines connected between a network bus and a plurality of power sources. Each receiving line is connected to a...
5883578 Loss of potential determination for use in protective relays for electric power systems  
The positive sequence voltage on the power line is measured at a given time, i.e. the present time, and also for one cycle earlier, and the ratio thereof is then compared against a threshold value...
5875087 Circuit breaker with integrated control features  
A digitally controlled circuit breaker includes a conventional thermal circuit breaker (10) which is controlled by a solenoid (16) to override the thermal aspect thereof. The solenoid (16) is...
5828309 Power source miswiring detection apparatus  
A power source miswiring detection apparatus for detecting a miswiring of wires of a power source, including a pulse generator for generating a first pulse having a pulse width corresponding to a...
5815357 Method and apparatus for three-phase sensing using two current transformers  
A method and apparatus is disclosed for complete three-phase sensing using two current transformers. Two phases of a three-phase system are used as the primary windings in each current transformer...
5798932 Methods and apparatus for removing error due to decaying offsets from measured power system currents  
A digital decaying current offset correction method and apparatus, in one aspect, separates the requirements of detecting fault existence from the requirements of detecting fault location. Once the...
5796565 Apparatus and method for starting and protecting a three-phase motor  
Apparatus for protecting and starting a three-phase motor uses the three-phase field rotation torque produced by three voltage coils, connected to a three-phase power supply, spaced 120 degrees...
5784240 Method and apparatus for limiting current surge upon transfer of a load between A.C. power sources  
A method of and apparatus for actuating an automatic transfer switch for disconnecting a motor load from a normal source of voltage and reconnecting the load to an alternate source of voltage at a...
5754440 Apparatus for harmonic analysis of waveforms in an AC electrical system  
A monitor for an ac electrical system generates on-line a display presenting the values, either in magnitude or as a percent of the fundamental, of 50 harmonics of any of the currents and voltages...
5729421 Circuit analyzing system  
A circuit analyzing system includes a current transformer for extracting current from a phase or neutral conductor of a three phase line, a filter connected to the output of the current transformer...
5706159 Circuit interrupter including an electric arc monitoring circuit  
A circuit interrupter including an improved arc detection system which trips the interrupter in response to currents having frequencies and/or characteristics associated with arcing within the...
5668692 Self-powered circuit interruption arrangement  
A circuit interrupter arrangement for interrupting current in a circuit path includes a hysteresis control circuit arranged to control a power supply charge-accumulation switch and an undervoltage...
5627714 Electronic thermal protection device  
Electronic device for thermal protection of a load (M) by cutting off the polyphase power supply to said load, including current transformers (Ti 1 , Ti 2 , Ti 3 ) installed on the wires (L 1 , L 2...
5602707 Detection of transformer high side fuse operations in a power transmission system  
Voltage comparisons are made for each of the phase-phase voltages on a low side of a distribution transformer in a power system against a threshold, approximately 0.7 nominal secondary voltage,...
5602709 High impedance fault detector  
A method and apparatus for detecting high impedance faults and other arcing phenomena in an electrical distribution system. Electrical signals on the distribution system are monitored and a number...
5598312 Device for controlling a mechanism driven by a lens one electric motor  
The invention relates to a device for controlling a mechanism driven by at least one electric motor (11, 12), said device comprising a circuit (20, 38) for detecting the power consumption of the...
5590012 Electric arc detector sensor circuit  
A sensor arrangement for producing a signal representative of currents having frequencies and/or characteristics associated with arcing within an alternating current electrical system. The...
5570258 Phase monitor and protection apparatus  
A phase monitor and protection circuit is shown in which an impedance network (21, 23, 25) in a respective branch (20, 22, 24) connected to a neutral (26) is coupled to each phase of a three phase...
5570257 Phase sequence wiring protection apparatus  
A phase sequence protection circuit is shown in which first and second resistors (R1, R2) and a first capacitor (C1) all having equivalent impedance are connected in a Y configuration and coupled...
5559719 Digitally controlled circuit interrupter with improved automatic selection of sampling interval for 50 Hz and 60 Hz power systems  
A circuit interrupter with a digital trip unit automatically sets the sampling interval appropriate for the 50 Hz or 60 Hz distribution system to which the interrupter is connected. In order to...
5555182 Source quality monitoring system  
A digital signal processor implemented monitoring circuit for detecting phase and magnitude disruptions in multi-phase alternating current input signals. A phase lock loop receives multi-phase...
5506743 Solid state overload relay with phase unbalance protection having RMS current approximation  
A solid state overload relay utilizes an apparatus that converts the current of a polyphase electrical load to a voltage signal approximately proportional to the RMS current of the load. In...
Matches 1 - 50 out of 209 1 2 3 4 5 >