Abstract: A method of operating a relay device, in an electrical circuit comprising first and second main circuit breakers, and a bus tie circuit breaker connecting the first and second main circuit breakers, the method comprising computing a first positive sequence current phasor for the first main circuit breaker and a second positive sequence current phasor for the second main circuit breaker computing a first positive sequence voltage phasor for the first main circuit breaker and a second positive sequence voltage phasor for the second main circuit breaker; computing a correction of the first positive sequence voltage and second positive sequence voltage to a line-to-neutral phase angle reference if there is any rotation in a potential transformer connection; determining a fault has occurred when a magnitude of a current through at least one of the first main circuit breaker or the second main circuit breaker exceeds a predetermined threshold; determining a phase angle difference by comparing the phase angle of the

Abstract: A method of operating a relay device, the method comprising the steps of: providing main circuit-breakers and a bus-tie-breaker connecting the main-circuit-breakers; defining a partial-differential-zone comprising a main circuit breaker and the bus-tie breaker; assigning a first value to the direction of the fault current flowing into the partial differential zone;—assigning a second value to the direction of the fault currents flowing out of the partial-differential-zone, wherein the first value is not equal to the second value;—comparing the values assigned to the fault currents; determining if the fault currents are flowing into the partial differential zone; and determining if at least two of the fault-currents is flowing in a different direction with respect to the partial-differential-zone wherein one of the fault currents is flowing into the partial-differential-zone and one of the fault currents is flowing out of the partial differential zone.

Abstract: The measurement of analog coil voltage and coil current during the energizing of the circuit breaker coil that is connected to the output contact of a protective circuit breaker relay in order to detect an incipient failure of the circuit breaker mechanism.

Abstract: The measurement of analog coil voltage and coil current during the energizing of the circuit breaker coil that is connected to the output contact of a protective circuit breaker relay in order to detect an incipient failure of the circuit breaker mechanism

Abstract: A method of operating a relay device, the method comprising the steps of: providing main circuit-breakers and a bus-tie-breaker connecting the main-circuit-breakers; defining a partial-differential-zone comprising a main circuit breaker and the bus-tie breaker; assigning a first value to the direction of the fault current flowing into the partial differential zone; -assigning a second value to the direction of the fault currents flowing out of the partial-differential-zone, wherein the first value is not equal to the second value; -comparing the values assigned to the fault currents; determining if the fault currents are flowing into the partial differential zone; and determining if at least two of the fault-currents is flowing in a different direction with respect to the partial-differential-zone wherein one of the fault currents is flowing into the partial-differential-zone and one of the fault currents is flowing out of the partial differential zone.

Abstract: A method of operating a relay device, the method comprising the steps of: computing positive-sequence first and second current-phasor for the first and second main circuit-breakers and computing currents from phasors, and the bus-tie-breaker; computing positive-sequence voltage for the bus-tie-breaker; triggering a method when at least one fault current at the bus-tie-breaker exceeds a threshold, without the presence of a fault on one of the feeders; determining whether the fault is internal or external, wherein the fault is internal if the positive-sequence current of the first and second main circuit breakers is in phase; and wherein if the positive-sequence current through the first main circuit breaker is not in-phase with the positive-sequence current through the second main circuit breaker, the fault is external to the bus; determining whether the fault is on a first or second side of the tie circuit; and locating the fault.

Abstract: A method for measuring a rate of change of frequency includes estimating at least one phasor value, estimating a frequency based on the estimated at least one phasor value, compensating the estimated at least one phasor value based on the estimated frequency, calculating a frequency based on the compensated at least one phasor value, and calculating a rate of change of the calculated frequency based on the calculated frequency.

Abstract: A method and apparatus is disclosed for providing protection against arc flash during maintenance on a low voltage power circuit including a circuit breaker having a specified trip function for responding to a fault is provided. The specified trip function is overridden with a maintenance trip function that results in reduced arc energy in the fault during a trip over arc energy during a trip with the specified trip function. The specified trip function is restored following maintenance.

Abstract: A micro-electromechanical system (MEMS) switch array for power switching includes an input node, an output node, and a plurality of MEMS switches, wherein the input node and the output node are independently in electrical communication with a portion of the plurality of MEMS switches, and wherein a failure of any one of the plurality of MEMS switches does not render ineffective another MEMS switch within the MEMS switch array.

Abstract: A system is presented. The system includes detection circuitry configured to detect occurrence of a zero crossing of an alternating source voltage or an alternating load current. The system also includes switching circuitry coupled to the detection circuitry and comprising a micro-electromechanical system switch. Additionally, the system includes control circuitry coupled to the detection circuitry and the switching circuitry and configured to perform arc-less switching of the micro-electromechanical system switch responsive to a detected zero crossing of an alternating source voltage or alternating load current.

Abstract: A system is presented. The system includes a first micro-electromechanical system switch. Further, the system includes arc suppression circuitry coupled to the first micro-electromechanical system switch, wherein the arc suppression circuitry comprises a balanced diode bridge and is configured to facilitate suppression of an arc formation between contacts of the first micro-electromechanical system switch.

Abstract: A reactive power compensation system includes a distributed energy resource situated at a local location configured to also receive power from a remote location by a distribution feeder line. The distributed energy resource includes an inverter including power semiconductor switching devices and an inverter controller configured for controlling the power semiconductor switching devices so as to provide reactive power support to the distribution feeder line.

Abstract: A method for measuring a rate of change of frequency includes estimating at least one phasor value, estimating a frequency based on the estimated at least one phasor value, compensating the estimated at least one phasor value based on the estimated frequency, calculating a frequency based on the compensated at least one phasor value, and calculating a rate of change of the calculated frequency based on the calculated frequency.

Abstract: A method and system for monitoring and controlling a power distribution system is provided. The system includes a plurality of circuit breakers and a plurality of node electronic units. Each node electronic unit is mounted remotely from an associated circuit breaker that is electrically coupled with one of the node electronic units. The system also includes a first digital network, and a first central control unit. The first central control unit and the plurality of node electronic units are communicatively coupled to the first digital network. The method includes receiving digital signals from each node electronic unit at the central control unit, determining an operational state of the power distribution system from the digital signal, and transmitting digital signals to the plurality of node electronic units such that the circuit breakers are operable from the first central control unit.

Abstract: A phasor measurement system is provided for computing synchronized phasor measurements. The phasor measurement system includes acquisition circuitry for acquiring voltage or current values from a power line, sampling circuitry for sampling the voltage or current values, and processing circuitry for computing a phasor and at least one time derivative of the phasor based on the sampled voltage or current values and for computing a synchronized phasor value based on the phasor and the at least one time derivative of the phasor.

Abstract: A method for locating a ground fault in an electrical power distribution system includes providing a plurality of current sensors at a plurality of locations in the electrical power distribution system. The method further includes detecting a ground fault in the electrical power distribution system. Current is monitored at a plurality of locations in the electrical power distribution system via the current sensors and a test signal is introduced into the electrical power distribution system via a test signal generating device. The plurality of locations are monitored to locate the ground fault between a location at which the test signal is detected and a downstream location at which the test signal is not detected.

Abstract: An apparatus for anti-islanding protection of a distributed generation with respect to a feeder connected to an electrical grid is disclosed. The apparatus includes a sensor adapted to generate a voltage signal representative of an output voltage and/or a current signal representative of an output current at the distributed generation, and a controller responsive to the signals from the sensor. The controller is productive of a control signal directed to the distributed generation to drive an operating characteristic of the distributed generation out of a nominal range in response to the electrical grid being disconnected from the feeder.

Abstract: A fault current limiter (FCL) comprises: an air core flat clock spiral inductor comprising wound electrically conductive material and insulated turns; and two terminations configured for attaching the spiral inductor in series with a power carrying conductor.

Abstract: A method for determining transient errors in an unsynchronized, digital current differential transmission line protection system includes receiving a first current phasor measurement at a time, t, and receiving a second current phasor measurement at time t. The second current phasor is adjusted so as to account for a determined offset between a first sampling clock associated with the first current phasor measurement and a second sampling clock associated with the second current phasor measurement, thereby resulting in a rotated second current phasor measurement. A residual transient error is then obtained from the rotated second current phasor measurement and the first current phasor measurement.

Abstract: A method for compensating for communications channel delay asymmetry in a current differential protection system includes determining an apparent sampling clock offset for a communications channel, the apparent sampling clock offset between a first sampling clock and a second sampling clock configured within the current differential protection system. An apparent global positioning system (GPS) clock offset is determined for the communications channel, the apparent GPS clock offset between a plurality of GPS time stamps corresponding to the first and said second sampling clocks. A compensated clock offset is determined by subtracting the apparent GPS clock offset from the apparent sampling clock offset so as to cancel out a channel asymmetry component of deviation in the apparent GPS and sampling clock off-sets.