With Differential Sensing Means Patents (Class 361/36)
  • Patent number: 11921170
    Abstract: A method for protecting a low-voltage distribution network. The low-voltage distribution network includes a low-voltage side of a three-phase distribution transformer that is configured to supply electrical power to at least one single-phase load through a respective distribution line of a plurality of three-phase distribution lines distribution lines. The method includes measuring variations of a periodic neutral-to-ground voltage between a neutral terminal of the three-phase distribution transformer and a local ground node by sampling the variations at a sampling frequency, detecting a fault in the low-voltage power distribution network based on the variations of the periodic neutral-to-ground voltage, and disconnecting the low-voltage side from the low-voltage power distribution network responsive to the fault being detected.
    Type: Grant
    Filed: April 15, 2022
    Date of Patent: March 5, 2024
    Assignees: ELECTRONIC SAZAN FAN ARIA COMPANY
    Inventors: Mahdi Davarpanah, Ahmadreza Darabi, Pooria Allah Karami, Hamed Morsali
  • Patent number: 11879928
    Abstract: There is provided mechanisms for differential protection of a transmission line (20) of a transmission system (25). A method comprises obtaining a restraining current and a differential current from the transmission line (S102). The method comprises determining a compensation current for the differential current (S104). The method comprises providing the differential current as compensated for by the compensation current and the restraining current to a differential protection arrangement for making a trip decision (S106). The method comprises detecting an internal fault for the transmission system (S108). The method comprises, as a result thereof, providing the differential current without being compensated for by the compensation current and the restraining current to the differential protection arrangement for making the trip decision (S110).
    Type: Grant
    Filed: January 7, 2020
    Date of Patent: January 23, 2024
    Assignee: Hitachi Energy Ltd
    Inventors: Jianping Wang, Zhanpeng Shi, Youyi Li
  • Patent number: 11695267
    Abstract: The present disclosure relates to a protective relay detecting disconnection in a circuit comprising a disconnection detection unit including a plurality of nodes connected to both ends of an output of a transformation unit, a reference voltage generation unit forming a reference voltage, and a plurality of resistors forming a voltage dividing resistor and connecting the plurality of nodes and the reference voltage generation unit; a sensing voltage generation unit applying a voltage for forming a predetermined voltage difference with respect to the reference voltage; and a disconnection determination unit connected to a first node, in which the magnitude of a voltage signal applied by the voltage dividing resistor varies depending on whether at least one of the transformation unit and the circuit connected to the transformation unit is disconnected, and detecting whether at least one of the transformation unit and the circuit connected to the transformation unit is disconnected.
    Type: Grant
    Filed: November 9, 2020
    Date of Patent: July 4, 2023
    Assignee: LS ELECTRIC CO., LTD.
    Inventor: Sangtack Shin
  • Patent number: 11018497
    Abstract: In-phase transfer of an electric power source to a load bus from a first feeder to a second feeder is disclosed herein. Voltage phase difference, voltage frequency difference, and voltage rate-of-change of frequency difference, between the second feeder and the load bus are used along with a breaker delay time to determine whether the breaker will close while the phase of the second feeder and the load bus are within an acceptable range. One or more breaker close time checks may be performed, including a breaker close time consistency check and a breaker close time uncertainty check.
    Type: Grant
    Filed: April 1, 2020
    Date of Patent: May 25, 2021
    Assignee: Schweitzer Engineering Laboratories, Inc.
    Inventors: Marcos A. Donolo, Jay Hartshorn
  • Patent number: 10916932
    Abstract: A method of protecting a power transformer including: monitoring an external fault indication signal; carrying out locally a fault determination; carrying out locally an inrush current determination; and issuing a final trip signal to protect the power transformer if the external fault indication signal identifies that a fault has occurred and the locally carried out fault determination confirms that a fault has occurred; or the external fault indication signal identifies that a fault has occurred and the locally carried out fault determination identifies that no fault has occurred but after a predetermined delay the locally carried out inrush current determination confirms the absence of an inrush current.
    Type: Grant
    Filed: October 12, 2016
    Date of Patent: February 9, 2021
    Assignee: General Electric Technology GmbH
    Inventors: Hengxu Ha, Yu Weng, Gajendiran Balakrishnan
  • Patent number: 10871513
    Abstract: A differential protection method for generating a fault signal. Current measurement values are acquired at different measuring points of a component. Differential current values and stabilizing values are formed using the current measurement values, and the fault signal is generated when a tripping range test indicates that a measured value pair formed from one of the differential current values and a respective associated stabilizing value lies in a predetermined tripping range. Differential current values are estimated from successive differential current values and associated stabilizing values and associated estimated stabilizing values are formed. A value of an expected future trend of the differential current values and of the stabilizing current values is estimated. A tripping range test finds the position of a measured value pair formed from an estimated differential current value and the respective associated estimated stabilizing value.
    Type: Grant
    Filed: November 26, 2012
    Date of Patent: December 22, 2020
    Assignee: Siemens Aktiengesellschaft
    Inventor: Frank Mieske
  • Patent number: 10551425
    Abstract: The present disclosure relates to a method for quickly identifying disconnection of a Current Transformer (CT) in protection of a 3/2 connection mode based bus. The present disclosure can quickly and accurately identify the disconnection of the CT, thereby avoiding the problem of a maloperation in protection of a bus caused by the disconnection of the CT.
    Type: Grant
    Filed: November 22, 2016
    Date of Patent: February 4, 2020
    Assignees: XJ GROUP CORPORATION, XJ ELECTRIC CO., LTD., XUCHANG XJ SOFTWARE TECHNOLOGY CO., LTD., STATE GRID CORPORATION OF CHINA
    Inventors: Jidong Huang, Chuankun Ni, Hui Tang, Zhiyong Wang, Feng Xiao, Shasha Hu, Yun Gong, Guangjie Feng, Shusheng Li, Ning Yang, Yanhai Zhang
  • Patent number: 10305932
    Abstract: Unique systems, methods, techniques and apparatuses of a substation phasor data concentrator (ssPDC) is disclosed herein. One exemplary embodiment is a method for operating an electrical substation including a merging unit (MU), a phasor measurement unit (PMU), and a substation phasor data concentrator (ssPDC).
    Type: Grant
    Filed: December 21, 2016
    Date of Patent: May 28, 2019
    Assignee: ABB Inc.
    Inventors: Junho Hong, Reynaldo Nuqui
  • Patent number: 10305272
    Abstract: An apparatus for detecting disconnection of a secondary side of a current transformer includes a sampling circuit coupled to the secondary side of the current transformer that samples signals from the secondary side of the current transformer. A pull-up circuit is switchably coupled to the sampling circuit in response to a coupling signal in a diagnostic phase. A processor is coupled to the sampling circuit for receiving sampled signals from the sampling circuit. The processor extracts corresponding signal information from the sampled signals and stores the extracted signal information in a memory. The extracted signal information corresponds to statuses that the secondary side of the current transformer is connected or disconnected to a load. A detector is coupled to the processor and the memory, and accesses the memory using the signal information of the sampled signals.
    Type: Grant
    Filed: March 20, 2017
    Date of Patent: May 28, 2019
    Assignee: NXP USA, INC.
    Inventors: Changhao Shi, Rui Lv, Dechang Wang
  • Patent number: 10132840
    Abstract: The invention is based on an electrical current measuring device for measuring at least one alternating current, with at least one inductive coupling unit, which is intended to convert at least one electrical primary signal into at least one electrical secondary signal, and with a computing unit, which is intended to determine the primary signal from the secondary signal. The computing unit is intended to take into account at least one higher harmonic of the secondary signal when determining the primary signal.
    Type: Grant
    Filed: September 20, 2016
    Date of Patent: November 20, 2018
    Inventor: Wilhelm Fromm
  • Patent number: 9065268
    Abstract: An inrush-current suppressing device includes a residual-magnetic-flux calculation unit that obtains a residual magnetic flux generated within a three-phase transformer, an input magnetic-flux-error calculation unit that obtains a closing-phase input magnetic-flux error, a closing-order determination unit that determines a closing order of phases of a three-phase breaker, a target-closing-phase/time setting unit that sets a time from a reference point to a target closing phase of a first closing phase as a first target closing time, and sets a time obtained by adding up a time from the reference point to a target closing phase of a second closing phase and a delay time set to exclude a period in which a magnetic flux in the first closing phase possibly saturates as a second target closing time, and a closing control unit that generates and outputs a closing control signal to close each phase at the target closing time.
    Type: Grant
    Filed: April 8, 2010
    Date of Patent: June 23, 2015
    Assignee: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Tomohito Mori, Haruhiko Koyama, Aya Yamamoto
  • Patent number: 9008982
    Abstract: The present disclosure provides systems and methods for calculating the flux in a core of an unloaded power transformer using current measurements taken from a capacitance-coupled voltage transformer (CCVT) attached to the same phase line as the power transformer. According to various embodiments, the current sensors may both be positioned at zero-voltage points in the CCVT, eliminating the need for high-voltage insulated current sensors. An intelligent electronic device (IED) may determine the magnetic flux within the core of the power transformer using the measured and/or derived currents through capacitive assemblies of the CCVT. The IED may calculate the residual flux in the power transformer when it is de-energized. The IED may use the calculated residual flux to facilitate an optimized re-energization of the power transformer, thereby reducing inrush currents during re-energization.
    Type: Grant
    Filed: March 9, 2012
    Date of Patent: April 14, 2015
    Assignee: Schweitzer Engineering Laboratories, Inc.
    Inventor: Demetrios A. Tziouvaras
  • Patent number: 8854776
    Abstract: Disclosed are a relay and method for protecting a transformer, and a transformer protecting system having the same. In the present disclosure, whether a transformation ratio of a transformer has been correctly set or not may be determined based on an inner algorithm. If it is determined that the transformation ratio of the transformer has been incorrectly set, a user may be informed to reset the transformation ratio. This may prevent a malfunction of the relay when the system is operated, and may enhance a system stability.
    Type: Grant
    Filed: January 19, 2012
    Date of Patent: October 7, 2014
    Assignee: LSIS Co., Ltd.
    Inventors: Ui Jai Lim, Jong Jin Jung
  • Publication number: 20140133054
    Abstract: A safety apparatus and method for monitoring a liquid-filled power transformer wherein there is provided a sensing device associated with an electronic unit. The sensing device is suitable to be at least partially immersed into liquid and includes at least one movable part displaceable by movements of the liquid. The electronic unit detects signals indicative of an actual position of the movable part and is arranged to provide, based on the detected signals, data related to actual conditions of the transformer and/or of its cooling liquid.
    Type: Application
    Filed: January 23, 2014
    Publication date: May 15, 2014
    Applicant: ABB TECHNOLOGY AG
    Inventors: Carlo CAROLLO, Andrea TONIN, Emanuele RAMPONI
  • Publication number: 20140111889
    Abstract: A method to avoid a single point of failure in a system that includes at least two monitoring devices, at least two power supplies and a switching device coupled between the monitoring devices and the power supplies. The method includes performing a test that can determine if two monitoring devices are receiving power from the power supply, generating an error code and varying a position of one or more switches in a switching device based on the error code.
    Type: Application
    Filed: October 24, 2012
    Publication date: April 24, 2014
    Applicant: General Electric Company
    Inventor: Ramesh Pai Brahmavar
  • Publication number: 20130335864
    Abstract: An electronic system to discharge a transformer in case of a failure during a charging phase of the transformer. The system includes the transformer having a primary winding with a first terminal connected to a battery voltage and with a second terminal for generating a primary voltage signal, includes a switch serially connected to the primary winding and having a control terminal carrying a control voltage signal for opening or closing the switch and includes an electronic circuit. The electronic circuit further includes a current generator and a voltage clamping.
    Type: Application
    Filed: May 23, 2013
    Publication date: December 19, 2013
    Applicant: STMicroelectronics S.r.I.
    Inventors: Calogero Andrea Trecarichi, Giovanni Luca Torrisi, Donato Tagliavia
  • Publication number: 20130279048
    Abstract: A method and device are disclosed for supervising the operation of plural current transformers and for prevention of a malfunction, such as false tripping of power in an electrical system. Exemplary embodiments can include measuring current parameters (e.g., magnitude and phase angle) for each winding in current transformer (CT) sets. A negative sequence current can be calculated from measured phase currents and a fault condition determined. A phase angle difference parameter derived from phase measurements between two healthy CTs can be used as an additional condition parameter for reliable operation of equipment in the electrical system.
    Type: Application
    Filed: June 18, 2013
    Publication date: October 24, 2013
    Inventors: Ylinen JUHA, Shah Nayan, Kandakatta Murali
  • Patent number: 8553379
    Abstract: Transformer differential protection is provided by measuring a plurality of currents corresponding to a first set of windings and a second set of windings of a transformer, and compensating the currents based on their respective flows through either the first set of windings or the second set of windings. The compensated currents may be intentionally augmented to compensate for magnetizing inrush and/or stationary overexcitation conditions associated with the transformer. Augmentation based on stationary overexcitation, for example, may be based on either harmonic restraint or an addition of a V/Hz ratio to a restraining signal. A complex current ratio is calculated corresponding to the plurality of compensated currents. The complex current ratio may be based on a two-terminal equivalent power apparatus. Then, an alpha plane analysis is applied to the complex current ratio. Based on the alpha plane analysis, a power apparatus that includes the transformer is selectively tripped.
    Type: Grant
    Filed: September 17, 2009
    Date of Patent: October 8, 2013
    Assignee: Schweitzer Engineering Laboratories Inc
    Inventors: Bogdan Z. Kasztenny, Normann Fischer
  • Patent number: 8405944
    Abstract: A distributed busbar protection system using time-stamped data gathered from measurement devices in an electrical power system bus arrangement by respective intelligent electronic devices (IEDs). The IEDs may derive the timestamp information from a clock or other time source, which may be synchronized to a common time source and/or an absolute time. The time-stamped measurement data may be used by a protection device to monitor and/or protect the electrical power system. The protection device may include a real-time vector processor, which may time-align the time-stamped data, determine one or more bus differential protection zones, and implement a differential protection function within each of the protection zones. One or more protective control signals may be transmitted to the IEDs to trip the corresponding breakers and clear the bus fault.
    Type: Grant
    Filed: September 18, 2009
    Date of Patent: March 26, 2013
    Assignee: Schweitzer Engineering Laboratories Inc
    Inventors: Marcos A. Donolo, Armando Guzman-Casillas, Edmund O. Schweitzer, III
  • Patent number: 8351169
    Abstract: The present invention relates to a system and method for preventing, protecting OLTC from fire and/or preventing, protecting and/or detecting explosion and/or resulting fire of electrical transformer (30) in advance before decomposition of combustible coolant fluid (11)/dielectric oil.
    Type: Grant
    Filed: January 1, 2009
    Date of Patent: January 8, 2013
    Assignee: CTR Manufacturing Industries Limited
    Inventor: Vijaykumar Kisanrao Wakchaure
  • Patent number: 8315022
    Abstract: An electrical power system may comprise a power source, an electrical load and an interconnection path between the power source and the electrical load. At least one power-source current transformer may be positioned at the power source. At least one remote current transformer may be positioned remotely from the power-source current transformer so that a portion of the interconnection path is between the power-source and the remote current transformer. A control circuit may be interposed between the power-source and remote current transformers and may be responsive to current imbalance between the power-source and remote current transformers to disconnect the power source from the electrical load in the event of such imbalance. The at least one power-source current transformer may comprise a secondary winding having first and second ends, and a resistor connected across the first and second ends.
    Type: Grant
    Filed: April 6, 2010
    Date of Patent: November 20, 2012
    Assignee: Honeywell International Inc.
    Inventors: William Scherzinger, Michael Duddeck, Dwayne E. Burnett, David Hodge, Robert Cisneroz
  • Publication number: 20120236443
    Abstract: An inrush-current suppressing device includes: a residual-magnetic-flux calculating unit that calculates a residual magnetic flux in a reference phase of a three-phase transformer while assuming a maximum magnetic flux level generated at a time of applying a rated voltage as 1 PU based on a measurement result of a transformer-voltage measuring unit before and after opening a three-phase circuit breaker; a stationary-magnetic-flux calculating unit that calculates a stationary magnetic flux in the reference phase of the three-phase transformer with reference to the maximum magnetic flux level obtained as the 1 PU based on a measurement result of a power-supply-voltage measuring unit, in response to a closing command to the three-phase circuit breaker; and a control unit that actuates a switch of the three-phase circuit breaker corresponding to the reference phase at a timing when the stationary magnetic flux and the residual magnetic flux in the reference phase match each other.
    Type: Application
    Filed: January 13, 2010
    Publication date: September 20, 2012
    Applicant: MITSUBISHI ELECTRIC CORPORATION
    Inventors: Sadayuki Kinoshita, Kenji Kamei, Tomohito Mori
  • Patent number: 8248005
    Abstract: A braking circuit is adapted to supply generatively produced energy of the motor as load resistance to a bipolar transistor. The braking circuit has a voltage regulator, which controls a voltage, applied to the base terminal of the bipolar transistor to achieve an associated controlled voltage based on a reference voltage. A first power supply connector of the electrical motor, in the generator mode of operation of the electrical motor, is coupled to a collector terminal of the bipolar transistor and to the voltage input of a voltage regulator. A second power supply connector of the electrical motor is coupled to an emitter terminal of the bipolar transistor and is coupled to a reference input of the voltage regulator via a resistive branch including at least one electrical resistor.
    Type: Grant
    Filed: June 23, 2010
    Date of Patent: August 21, 2012
    Assignee: Dorma GmbH + Co. KG
    Inventor: Martin Römer
  • Publication number: 20120194949
    Abstract: Disclosed are a relay and method for protecting a transformer, and a transformer protecting system having the same. In the present disclosure, whether a transformation ratio of a transformer has been correctly set or not may be determined based on an inner algorithm. If it is determined that the transformation ratio of the transformer has been incorrectly set, a user may be informed to reset the transformation ratio. This may prevent a malfunction of the relay when the system is operated, and may enhance a system stability.
    Type: Application
    Filed: January 19, 2012
    Publication date: August 2, 2012
    Applicant: LSIS CO., LTD
    Inventors: Ui Jai LIM, Jong Jin JUNG
  • Patent number: 8169762
    Abstract: 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 concentric with the relay coil. Additional functions are thus provided in addition to the main relay switching function or functions. The concentric nature of the relay coil and the conducting loop create a current transformer between these elements. The additional functions include the ability to measure an alternating current (AC) current conducted by the conducting loop, the ability to detect and interpret an information signal imposed on power lines connected to the conducting loop, the ability to induce or impose an information signal on the conducting loop for transmission to power lies connected to the conducting loop, and the ability to measure a differential current between currents carried by the conducting loop and a second concentric conducting loop.
    Type: Grant
    Filed: April 20, 2009
    Date of Patent: May 1, 2012
    Assignee: Energy Safe Technologies, Inc.
    Inventors: Jeffrey Baxter, Brent Baxter, Michael Baxter, Ted Holbrook
  • Publication number: 20120019963
    Abstract: The invention is a device and method for eliminating core excitation losses in a distribution transformer when the transformer is not supplying power to loads. The invention consists of sensors, a control circuit, a user interface and a power contactor. The power contactor is connected on the line side of a transformer and is opened or closed automatically based on preprogrammed time or load criteria determined by the control circuit. In one operational mode and when the transformer is disconnected from the line, the control board generates low power pulses at the transformer load connection points in order to “search” for loads. If a load is detected, the transformer is reconnected by way of contactor closure. If the transformer load drops to zero, for a predetermined amount of time, the transformer is again disconnected and the pulsed load search is reestablished.
    Type: Application
    Filed: September 30, 2011
    Publication date: January 26, 2012
    Applicant: Xantrex Technology, Inc.
    Inventor: Rick West
  • Patent number: 8023572
    Abstract: 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 signaling circuit operable to be coupled to a communication bus. The differential signaling circuit can include a first current carrying element and a second current carrying element. The circuit can also include a shunt circuit including a first transformer. The first transformer can include a primary transformer element and a secondary transformer element. The first transformer can be operably associated with the communication bus.
    Type: Grant
    Filed: November 29, 2006
    Date of Patent: September 20, 2011
    Assignee: Dell Products, LP
    Inventor: Jeffrey C. Hailey
  • Patent number: 8013702
    Abstract: 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 structure of the electromagnetic transformer is mounted above the electromagnetic transformer. The power electronic module is removably mounted in a cavity of the pocket. The power electronic module includes a plurality of semiconductor switching devices and a plurality of connectors adapted to slidably engage the connectors of the pocket. The power electronic module is movable between a removed position, wherein the power electronic module is located outside the pocket, and an installed position, wherein the power electronic module is disposed in the cavity of the pocket and the connectors of the power electronic module engage the connectors of the pocket so as to electrically connect the power electronic module to the at least one winding structure.
    Type: Grant
    Filed: June 11, 2010
    Date of Patent: September 6, 2011
    Assignee: ABB Research Ltd.
    Inventors: Mohamed Y. Haj-Maharsi, Thomas J. Lanoue
  • Publication number: 20110063761
    Abstract: Transformer differential protection is provided by measuring a plurality of currents corresponding to a first set of windings and a second set of windings of a transformer, and compensating the currents based on their respective flows through either the first set of windings or the second set of windings. The compensated currents may be intentionally augmented to compensate for magnetizing inrush and/or stationary overexcitation conditions associated with the transformer. Augmentation based on stationary overexcitation, for example, may be based on either harmonic restraint or an addition of a V/Hz ratio to a restraining signal. A complex current ratio is calculated corresponding to the plurality of compensated currents. The complex current ratio may be based on a two-terminal equivalent power apparatus. Then, an alpha plane analysis is applied to the complex current ratio. Based on the alpha plane analysis, a power apparatus that includes the transformer is selectively tripped.
    Type: Application
    Filed: September 17, 2009
    Publication date: March 17, 2011
    Inventors: Bogdan Z. Kasztenny, Normann Fischer
  • Patent number: 7869167
    Abstract: 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 decomposition of combustible coolant fluid/dielectric oil.
    Type: Grant
    Filed: April 13, 2006
    Date of Patent: January 11, 2011
    Assignee: CTR Manufacturing Industries Limited
    Inventor: Kisanrao Vijaykumar Wakchaure
  • Publication number: 20100296205
    Abstract: The present invention relates to a system and method for preventing, protecting OLTC from fire and/or preventing, protecting and/or detecting explosion and/or resulting fire of electrical transformer (30) in advance before decomposition of combustible coolant fluid (11)/dielectric oil.
    Type: Application
    Filed: January 1, 2009
    Publication date: November 25, 2010
    Inventor: Vijaykumar Kisanrao Wakchaure
  • Patent number: 7839610
    Abstract: 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 generation section generating a predetermined second current; an integration section charging and discharging a capacitor in accordance with magnitude relation between the first current and the second current; a comparison section comparing a terminal voltage of the capacitor and a predetermined threshold voltage; and an output section generating a protection signal based on output logic of the comparison section. Such configuration permits appropriately preventing load burnout.
    Type: Grant
    Filed: October 2, 2007
    Date of Patent: November 23, 2010
    Assignee: Rohm Co., Ltd.
    Inventors: Seiichi Yamamoto, Takahiro Ota
  • Patent number: 7812615
    Abstract: 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 for detecting turn-to-turn faults in power transformer/autotransformer windings. All individual instantaneous phase currents of the protected object are measured, individual phase currents as fundamental frequency phasors are calculated, the contributions of the individual protected object sides negative sequence currents to the total negative sequence differential current are calculated by compensating for the phase shift of an eventual power transformer within the protected zone, the relative positions of the compensated individual sides negative sequence currents in the complex plane are compared, in order to determine whether the source of the negative sequence currents, i.e.
    Type: Grant
    Filed: December 22, 2004
    Date of Patent: October 12, 2010
    Assignee: ABB AB
    Inventors: Zoran Gajic, Ivo Brncic
  • Patent number: 7738221
    Abstract: 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 current. Effective detection of power transformer inrush conditions can enable blocking of a protection relay during inrush where the differential current may exceed a differential threshold value indicative of a fault without the presence of an actual fault. The outputs of the Rogowski coils, being proportional to the first time derivative of the sensed current, may be useful in the inrush detection method. Also, with reduced saturation concerns, the Rogowski coil protection system may employ a single slope response with increased sensitivity. A discrete time sampling technique for identifying low di/dt portions within the sensed current also may be useful in detecting power transformer inrush conditions.
    Type: Grant
    Filed: December 7, 2007
    Date of Patent: June 15, 2010
    Assignee: Cooper Technologies Company
    Inventors: Ljubomir A. Kojovic, Martin T. Bishop, Timothy R. Day
  • Publication number: 20100039737
    Abstract: To provide a magnetizing inrush current suppression device for transformer and control method of same, which accurately calculates the residual magnetic flux when a transformer installed in a non-solidly earthed system, is interrupted by circuit breakers, and which enables suppression of the magnetizing inrush current occurring when three single-phase circuit breakers or single-phase circuit breakers are used for simultaneously supplying power to three phases of the transformer, without providing a circuit breaker with a resistor or other equipment to enlarge the circuit breaker.
    Type: Application
    Filed: June 17, 2009
    Publication date: February 18, 2010
    Applicant: Kabushiki Kaisha Toshiba
    Inventors: Tadashi Koshizuka, Minoru Saito, Koichi Futagami, Hiroshi Kusuyama, Yoshimasa Sato
  • Patent number: 7633737
    Abstract: 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 least one varistor. The liquid immersed surge arrester also includes contacts on opposite ends of the module assembly with which the module assembly is connected to electrical equipment to be protected and to electrical ground. The liquid immersed surge arrester also includes a tank that houses the module assembly and the contacts. A fault-tolerant protection device for protecting electrical equipment includes a surge arrester to protect electrical equipment from damage during periods of voltage above a normal operating range. The fault-tolerant protection device also includes a surge durable fuse element to disconnect the surge arrester after failure of the surge arrester to allow unprotected operation of the electrical system.
    Type: Grant
    Filed: April 29, 2004
    Date of Patent: December 15, 2009
    Assignee: Cooper Technologies Company
    Inventors: Michael M. Ramarge, Alan P. Yerges
  • Publication number: 20090147412
    Abstract: 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 current. Effective detection of power transformer inrush conditions can enable blocking of a protection relay during inrush where the differential current may exceed a differential threshold value indicative of a fault without the presence of an actual fault. The outputs of the Rogowski coils, being proportional to the first time derivative of the sensed current, may be useful in the inrush detection method. Also, with reduced saturation concerns, the Rogowski coil protection system may employ a single slope response with increased sensitivity. A discrete time sampling technique for identifying low di/dt portions within the sensed current also may be useful in detecting power transformer inrush conditions.
    Type: Application
    Filed: December 7, 2007
    Publication date: June 11, 2009
    Applicant: Cooper Technologies Company
    Inventors: Ljubomir A. Kojovic, Martin T. Bishop, Timothy R. Day
  • Patent number: 7456601
    Abstract: 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 embodiment, a starting resistor and a starting bypass contactor are connected between the rotor of the motor and a low voltage source inverter. In an alternative embodiment, the arrangement of the first embodiment is altered by connecting a shorting contactor on one side to the junction of the voltage source inverter, the starting resistor and the starting bypass contactor so as to be short circuited on the opposite side of the shorting contactor.
    Type: Grant
    Filed: October 8, 2007
    Date of Patent: November 25, 2008
    Assignee: TM GE Automation Systems LLC
    Inventor: Paul S. Bixel
  • Publication number: 20080186641
    Abstract: 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 decomposition of combustible coolant fluid/dielectric oil.
    Type: Application
    Filed: April 13, 2006
    Publication date: August 7, 2008
    Inventor: V.K. Wakchaure
  • Publication number: 20080130179
    Abstract: 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 for detecting turn-to-turn faults in power transformer/autotransformer windings. All individual instantaneous phase currents of the protected object are measured, individual phase currents as fundamental frequency phasors are calculated, the contributions of the individual protected object sides negative sequence currents to the total negative sequence differential current are calculated by compensating for the phase shift of an eventual power transformer within the protected zone, the relative positions of the compensated individual sides negative sequence currents in the complex plane are compared, in order to determine whether the source of the negative sequence currents, i.e.
    Type: Application
    Filed: December 22, 2004
    Publication date: June 5, 2008
    Applicant: ABB AB
    Inventors: Zoran Gajic, Ivo Brncic
  • Patent number: 7365451
    Abstract: 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 with the ends of each of the primary windings of the array transformers; normally-off current bypass devices connected in parallel with the series connections of the primary windings of the array transformers and the switches at the transformer ends; AC-DC converter units having AC sides respectively connected secondary windings of the array transformers; and mutually independent DC circuits respectively connected to DC sides of the AC-DC converter units. By turning on the current bypass device of the primary winding of a specified array transformer and turning off the switches at the ends of that primary winding, it is possible to isolate the specified array transformer and the AC-DC converter unit connected to it.
    Type: Grant
    Filed: February 12, 2004
    Date of Patent: April 29, 2008
    Assignee: Mitsubishi Denki Kabushiki Kaisha
    Inventor: Tomohiko Aritsuka
  • Patent number: 7340355
    Abstract: 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 current and a magnetizing current, and, in particular, to a compensated current differential relaying method and system which can protect the transformer correctly irrespective of the level of remanent flux.
    Type: Grant
    Filed: May 9, 2005
    Date of Patent: March 4, 2008
    Assignee: Yong-Gyun Kim
    Inventors: Yong-Cheol Kang, Sang-Hee Kang
  • Patent number: 7336046
    Abstract: 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 (pulse width modulation) signal to PWM-control the drive signal, detects information about a short circuit in the path, and notifies the detected information about the short circuit. The control device comprises means for producing the PWM signal; means for inquiring of the drive device about the information about the short circuit at predetermined inquiry intervals; first determining means for determining whether or not the short circuit has been detected based on the information notified in response to the inquiry; and second determining means for determining how the short circuit occurs, based on history information in the information about the short circuit notified when the first determining means determines that the short circuit has been detected.
    Type: Grant
    Filed: July 19, 2006
    Date of Patent: February 26, 2008
    Assignee: Denso Corporation
    Inventor: Satoka Yasue
  • Patent number: 7294973
    Abstract: 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 the discharge tubes are connected individually; a power section for supplying ac current to the winding input end of the balance coil; and a control section for detecting a peak value of detection voltages corresponding to voltages at the winding output ends of the balance coil and for stopping the supply of the ac current from the power section when the peak value of the detection voltages is higher than a predetermined value.
    Type: Grant
    Filed: May 9, 2006
    Date of Patent: November 13, 2007
    Assignee: Sony Corporation
    Inventors: Masanobu Takahama, Yoshiki Oyama
  • Patent number: 7196884
    Abstract: 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 plurality of secondary current waveforms of the three-phase power system to the protective relay. The apparatus includes a first logic circuit and a second logic configured to provide corresponding first and second binary signals in response to respective comparisons of calculated current value(s) of a plurality of like-phase digitized current sample streams to respective threshold values. The apparatus also includes a set reset flip-flop having a set input adapted to receive the first and second binary signals to provide a third binary signal. The third binary signal indicates loss of a current transformer connection when the set input is asserted and indicates no loss of a current transformer connection when the reset input is asserted.
    Type: Grant
    Filed: March 2, 2005
    Date of Patent: March 27, 2007
    Assignee: Schweitzer Engineering Laboratories, Inc.
    Inventors: Armando Guzman-Casillas, Normann Fischer
  • Patent number: 6870719
    Abstract: 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 assembly (1) having such a device (20). According to the invention, zones (1a, 1b, 1c) bounded by current transformers (7) and possibly by open switches (3-5) are detected for an instantaneous topology of the switchgear (1), in each zone (1a, 1b, 1c) the signed current measurement signals are added and in the case of significant deviations of the current sum from zero, all current transformers (7) of the associated zone (1a, 1b, 1c) are identified as being problematic. Exemplary embodiments relate to, among other things: a warning counter (2e) for problematic current transformers (7); in the case of a defective current transformer (7), an operation with calculated currents or an automatic combining of zones (1a, 1b, 1c); and coordinating the plausibility test with switching actions.
    Type: Grant
    Filed: March 17, 2003
    Date of Patent: March 22, 2005
    Assignee: ABB Schweiz AG
    Inventors: Wolfgang Wimmer, Jan Schutter
  • Patent number: 6507184
    Abstract: 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 obtained for each phase. To compensate for any changes in phase introduced by the device between the first and second terminals, the measured currents obtained for each phase at those terminals are normalized using a novel, generalized normalization transform having the form: G(&thgr;)=cos(&thgr;)U+sin(&thgr;)J where U represents a unit zero degree phase shift with zero sequence components removed, and J represents a unit ninety degree phase shift with zero sequence components removed. From the normalized currents, a differential current is then calculated for each phase.
    Type: Grant
    Filed: March 28, 2001
    Date of Patent: January 14, 2003
    Assignee: ABB Automation Inc.
    Inventor: Joel A. B. Elston
  • Patent number: 6483680
    Abstract: 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 harmonic in addition to the magnitude ratio. This is accomplished by calculating and utilizing the complex second harmonic ratio. The specially shaped operating characteristic for the complex second harmonic ratio is made dynamic providing for better security without jeopardizing dependability of the transformer protective relay.
    Type: Grant
    Filed: July 21, 2000
    Date of Patent: November 19, 2002
    Assignee: General Electric Co.
    Inventors: Ara Kulidjian, Bogdan Kasztenny
  • Patent number: 6356421
    Abstract: 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 value. A restraining current value is obtained from processed winding current values. Second and fourth harmonic values of the differential current are obtained and are summed with a restraining current quantity which is a result of the restraining current multiplied by a slope characteristic factor. If the operating current value is greater than the sum of the restraining current quantity and the second and fourth harmonic values, an output signal is produced which may be used as a trip signal unless it is blocked by selected blocking signals generated by another portion of the system.
    Type: Grant
    Filed: November 29, 1999
    Date of Patent: March 12, 2002
    Assignee: Schweitzer Engineering Labs., Inc.
    Inventors: Armando Guzman-Casillas, Hector Altuve-Ferrer, Stanley E. Zocholl, Gabriel Benmouyal
  • Patent number: 6247003
    Abstract: 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 from the current transformer and determines within which of three ranges the value falls. If the value falls in a first range, the current measurement is provided to a protective device such as a relay. If the value falls in a second range, the current measurement is provided to an artificial neural network that produces an output that accounts for saturation of the current transformer. If the value falls in a third range, the current measurement is provided to another artificial neural network that produces an output that accounts for saturation of the current transformer.
    Type: Grant
    Filed: March 24, 1999
    Date of Patent: June 12, 2001
    Assignee: McGraw-Edison Company
    Inventors: James C. Cummins, David C. Yu, David T. Stone, Ljubomir A. Kojovic