Honeywell G.m.b.h.

The Texas A&m University System

Other

Nxtphase T&d Corporation

Leland Stanford Junior University

Alstom Technology Limited

Honeywell International Inc.

Nxtphase Technologies, Srl

Siemens Aktiengesellschaft

Seagate Technology Incorporated

General Electric Technology Gmbh

James N Blake

Bogdan Szafraniec

Farnoosh Rahmatian

Glen Aaron Sanders

Byoung Y Kim

Charles H Lange

John R Feth

Lee Kevin Strandjord

Herbert J Shaw

Alexander Tselikov

Carl Glasow

Jeffrey P Wilde

Ralph A Bergh

Clarence E Laskoskie

Rudolf C Dankwort

Dick Ang

Richard H Frische

Richard J August

Ren-Young Liu

Andrzej Klimek

Kevin B Dimond

Preston Dane

Michael J Putt

Yves Doin

Cataldo Diaferia

Alan Baker

Frédéric Leclerc

Shayne X Short

Helge E Engan

James D Hrabliuk

Joseph H Schaeffer

Helege E Engan

The open-phase condition of a standby power transformer is detected by monitoring functions of the phase currents. The functions have parameters calculated based on reference currents, which constitute a 'fingerprint' when all the phases are connected.

Methods and systems for open-phase detection in power transformers

Systems and methods according to these exemplary embodiments provide for methods and systems related to optical current sensors used to monitor standby power transformers, specifically fiber optical current and voltage sensors and, more particularly, to applications involving filters for use in such sensors, such as frequency tracking comb filters. According to one embodiment, a method for monitoring a connection condition of a stand by power transformer includes the steps of measuring a current flowing through a high voltage side of the standby power transformer using at least one optical current sensor disposed proximate to a current flow path of the high voltage side, using a comb filter to filter the measured current, determining whether the filtered, measured current is less than a predetermined threshold value; and generating an alarm indication that the high voltage side of the standby power transformer is unconnected.

Power transformers using optical current sensors

A master-slave current sensor system for measuring, for example, differential current on a transmission line is described. The slave current sensor can be periodically recalibrated (or have a compensation value re-calculated) based on the master sensor's average output, and the slave sensor can be unpowered and remote from an electronics box which receives its measurements. Health monitoring and fault location can also be performed using the master-slave optical current sensor system, optionally in conjunction with one or more voltage sensors.

Master-slave fiber optic current sensors for differential protection schemes

Systems and methods related to optical current and voltage sensors and, more particularly, to filters for use in such sensors. A fiber optic current sensor comprising: a light source; a polarization beam splitter connected to said light source having a reciprocal port and a non-reciprocal port; a Faraday rotator connected to said polarization beam splitter; a first quarter-wave plate connected to said Faraday rotator; a polarization maintaining fiber connected to said first quarter-wave plate; a second quarter-wave plate connected to said polarization maintaining fiber; a sensing fiber connected to said second quarter-wave plate; a detector connected to said polarization beam splitter via said non-reciprocal port and having an output; and an adaptive filter for filtering said output.

Adaptive filters for fiber optic sensors

An optical sensor configuration contains an optical current sensor and/or an optical voltage sensor. The sensor configuration further contains a first and a second hollow member, preferably ring shaped profiles, which are together disposed to form a hollow section. The sensor configuration further includes an optical fiber of the current sensor disposed in an annular groove, the groove being disposed at the boundary surface between the first hollow member and the second hollow member, and/or an optical fiber of the voltage sensor is disposed in a recess of the second hollow member. The first hollow member has an annular recess into which the second hollow member is disposed whereas the first hollow member is an L-shaped or U-shaped ring with two legs and the recess is formed between the two legs.

Optical sensor arrangement for electrical switchgear

Multi-phase, gas insulated electrical switchgear with optical voltage and/or current sensors are described. Compensation for contributions to sensor readings from non-associated conductors is provided. A processor is connected to voltage and/or current sensors which are placed near conductor whose voltages and/or currents are to be measured. The processor can receive outputs from those sensors and compensate the outputs for contributions which are attributable to sources other than the conductors which are intended to be measured.

Sensors and sensing methods for three-phase, gas insulated devices

A sensor provides an analog sensor output signal that is first converted by a A/D converter, followed by a digital signal processor having a digital signal output that is converted to an analog signal by way of a D/A converter so as to provide an analog information output signal indicative of a parameter quantity intended to be sensed. An analog dither signal and/or a digital dither signal is provided for modulating the A/D converter input signal and/or D/A converter input signal, respectively, separately, or in combination, to enhance dynamic range accuracy of the resultant analog information output signal representative of the quantity of the parameter intended to be sensed.

Wide dynamic range sensor signal processing method & circuitry for analog and digital information signals

An exemplary WDM coupling device may include optical fibers. The coupling device may also include region(s) having varying coefficients of thermal expansion. During a temperature variation, one or more of the region(s) may alter in size to substantially cancel temperature-dependent changes associated with the WDM coupling device.

Wavelength division multiplexing coupling device

In accordance with the preset invention, an optical interferometer employed as a current sensor is provided with visibility compensation and scale factor compensation. In accordance with the present invention, the interferometer is constructed so as to propagate a pair of optical beams along a defined optical path, where the optical interferometer includes a pair of optical beams that travel along at least a portion of the defined optical path such that a phase shift is induced between the pair of optical beams in response to a measureand, for example electrical current. At least one photodetector is responsive to at least a portion of the sum of the pair of optical beams and provide a beam output signal indicate thereof. From the beam output signal, a first signal is derived that is indicative of the visibility of the interferometer. A signal processor derives from the beam output signal an output signal indicative of the bias point of the interferometer, where the bias point is indicative of the induced phase shift in response to the measurand. A compensated interferometer output signal indicative of the induced phase shift is derived as a function of the visibility signal and bias point signal. In a specific embodiment of the invention, the visibility signal may simply be the output of a signal averaging circuit which in turn may adjust the gain of the signal processing circuit.

Optical interferometric sensor with measureand compensation that may selectively be used for temperature compensation and long term life degradation

A method and system for adjusting power at output ports of a wavelength division multiplexing (WDM) coupler. A loss element may be placed at one or more of the output ports of the WDM coupler. The loss element may have a filter characteristic that matches the temperature sensitivity coefficient of the WDM coupler. The filter characteristic may reject power at one of the two output ports as a function of temperature. As a result, the loss element may balance the power at the output ports of the WDM coupler despite temperature variations.

Wavelength division multiplexing coupler with loss element

A system and method for achieving, while using a laser and optical fibers, high signal-to-noise ratio. In particular, the system splits an incoming main light signal into two orthogonal polarization states, which then propagate through an optical circuit before recombining. The use of appropriate path differences ensures that the system is immune from the conversion of mode partition noise to intensity noise arising from the interference between parasitic light waves which traveled through the system in undesired polarization states.

Optical depolarizer

A method and system for aligning optical fibers includes aperturing the optical beams from the optical fibers at two points along a path. Photodetectors are placed on the apertures and the positions of the tips of the optical fibers are controlled using actuators to center the optical beams within the apertures.

Fiber optic alignment system and method

A sensor that measures a difference of currents at two locations along a conductor. The sensor uses two fiber optic current sensors. One current sensor at the first location measures current and has a nulling coil about its sensing loop, which carries current to null out the reading of current. Another current sensor at the second location measures current and also has a nulling coil about its sensing loop. The nulling coil of the latter sensor has the same current as the nulling coil of the sensor at the first location. For similar current sensors sensing the same magnitudes of current at their respective locations will have their outputs nulled to zero. However, if the first sensor output is nulled out and the sensor at the second location is sensing a different amount of current than the sensor at the first location, with the same amount of current in its nulling coil, then the output of the second sensor will indicate the difference of currents at the two locations, thereby indicating a loss or a gain of current along the conductor.

Fiber optic difference current sensor

A current sensor coil design for reducing or eliminating long undulations of magnetic sensitivity. Such reduction or elimination improves isolation of the current sensor such that proximate currents and accompanying effects do not affect the accuracy of the current sensor determination of a current being measured. Several designs, which may be incorporated separately or in combination, include modifying the specifications of the quarter waveplate, cutting the fiber of the sensor coil to a proper length, choosing a proper perimeter length of the sensor coil or head, and using a particular length of fiber adjusted to work in conjunction with a multi-wavelength or broadband light source.

Fiber-optic current sensor with improved isolation

Growing community of inventors

Scottsdale, AZ, United States of America

James N Blake