Pullman, WA, United States
Pullman, WA, United States

Schweitzer Engineering Laboratories, Inc. designs, manufactures, and supports products and services ranging from generator and transmission protection to distribution automation and control systems. Founded in 1982 by Edmund O. Schweitzer III, SEL shipped the world's first digital protective relay. Presently, the company designs and manufactures embedded system products for protecting, monitoring, control, and metering of electric power systems. E. O. Schweitzer Manufacturing, a manufacturer of fault indicators and sensors started by Edmund O. Schweitzer, Jr. in 1949, became a division of SEL in 2005. Wikipedia.


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Patent
Schweitzer Engineering Laboratories | Date: 2016-09-19

The present disclosure relates to detection of faults in an electric power system. In one embodiment, an incremental quantities subsystem is configured to determine a forward torque, an operating torque, and a reverse torque based on the plurality of time-domain representations of electrical conditions. Each of the forward torque, the operating torque, and the reverse torque may be integrated over an interval. A fault detection subsystem may determine an occurrence of the fault based on a comparison of the operating torque to the forward torque and the reverse torque. Further, a direction of the fault may be determined based on the comparison of the forward torque, the operating torque, and the reverse torque. A fault may be declared based on the comparison and the direction. A protective action subsystem may implement a protective action based on the declaration of the fault.


Patent
Schweitzer Engineering Laboratories | Date: 2016-11-02

Disclosed herein are systems for detecting a location of a fault on an electric power transmission line using a state-of-polarization traveling wave in an optical ground wire. Various embodiments may also detect a traveling wave on a conductor of the transmission system. The arrival times of the state-of-polarization traveling wave and the electrical traveling wave may be compared. Using the difference in times and the known propagation velocities of the traveling waves, a distance to the fault may be calculated. Arrival time of the state-of-polarization traveling wave may be calculated using electrical signals from photodetectors in an optical channel with polarizing filters at different orientations or reference frames.


Patent
Schweitzer Engineering Laboratories | Date: 2016-11-11

Systems and methods for detecting the failure of a precision time source using an independent time source are disclosed. Additionally, detecting the failure of a GNSS based precision time source based on a calculated location of a GNSS receiver is disclosed. Moreover, the system may be further configured to distribute a time derived from the precision time source as a precision time reference to time dependent devices. In the event of a failure of the precision time source, the system may be configured to distribute a time derived from a second precision time source as the precision time signal during a holdover period.


Patent
Schweitzer Engineering Laboratories | Date: 2016-03-02

Monitoring thermal conditions of an electric motor using current signals from power supplied to the motor is disclosed herein. The current signals may be used to calculate composite current values which may be used to calculate slip. The slip may be used to provide thermal monitoring and protection to the electric motor. Slip may be calculated using only values from the stator of the electric motor for providing thermal monitoring and protection to electric motors where rotor measurements are not available.


The present disclosure pertains to systems and methods for detecting faults in an electric power delivery system. In one embodiment, a system may include a data acquisition subsystem configured to receive a plurality of representations of electrical conditions. The system may also include a traveling wave differential subsystem configured to determine an operating quantity based on the plurality of representations of electrical conditions. The traveling wave differential subsystem may also determine a restraint quantity based on the plurality of representations of electrical conditions. The traveling wave differential subsystem may detect a traveling wave generated by the fault based on the plurality of representations. A fault detector subsystem may be configured to declare a fault based on a comparison of the operating quantity and the restraint quantity. A protective action subsystem may implement a protective action based on the declaration of the fault.


Patent
Schweitzer Engineering Laboratories | Date: 2016-02-19

Disclosed herein are systems and methods for estimating a period and frequency of a waveform. In one embodiment a system may comprise an input configured to receive a signal comprising a representation of the waveform. A period determination subsystem may calculate an estimated period of the signal based on a period determination function. An estimated period adjustment subsystem may determine an adjustment to the estimated period based on a result of the period determination function. A quality indicator subsystem configured to evaluate a measurement quality indictor function based on the estimated period, and to selectively update the period of the waveform based on the measurement quality indicator. A control action subsystem configured to implement a control action based on the period of the waveform.


Patent
Schweitzer Engineering Laboratories | Date: 2016-04-12

A location of a broken electrical conductor of an electric power delivery system may be detected by monitoring a rate of change of phase voltage and/or a rate of change of zero-sequence voltage at various points on the conductor. Intelligent electronic devices (IEDs) such as phasor measurement units may be used to obtain measurements and calculate synchrophasors. The synchrophasors may be used by a central controller to determine which two continuous IEDs measure rates of change of voltages of opposite polarities, where the broken conductor is between the two continuous IEDs. The synchrophasors may be used by a central controller to determine which two continuous IEDs where one exhibits a zero-sequence voltage magnitude that exceeds a predetermined threshold for a predetermined time, wherein the zero-sequence voltage magnitude of the other of the continuous IEDs does not exceed the predetermined threshold.


Patent
Schweitzer Engineering Laboratories | Date: 2016-02-11

Disclosed herein are systems for detecting a location of a fault on an electric power transmission line using a state-of-polarization traveling wave in an optical ground wire Various embodiments may also detect a traveling wave on a conductor of the transmission system. The arrival times of the state-of-polarization traveling wave and the electrical traveling wave may be compared. Using the difference in times and the known propagation velocities of the traveling waves, a distance to the fault may be calculated. Arrival time of the state-of-polarization traveling wave may be calculated using electrical signals from photodetectors in an optical channel with polarizing filters at different orientations or reference frames.


Patent
Schweitzer Engineering Laboratories | Date: 2016-04-28

Disclosed herein are various embodiments of devices and related methods for detecting an electrical arc event using a motor management relay and for suppressing the electrical arc event. The motor management relay may incorporate an optical arc-flash sensor configured to detect an optical event. Control logic may analyze the optical event and determine whether the optical event corresponds to an electrical arc event. When an electrical arc event is detected an instruction may be issued via a control port in communication with the control logic to implement a protective action. According to various embodiments, a plurality of sensors for monitoring electrical characteristics of a motor may also be in communication with the control logic. Input from the sensors may be analyzed in order to determine whether the optical event corresponds to an electrical arc event.


Patent
Schweitzer Engineering Laboratories | Date: 2016-01-19

A multilingual power system protection device to facilitate communications in different human languages over different communication ports is described herein. In one embodiment, an electric power system device may include communication ports configured to receive inputs in different human languages and a monitored equipment interface in communication with a component of an electric power system. The electric power system device may receive an input on one of the communication ports and may associate the input with a function implemented by the component of the electric power system. The electric power system device may further generate a response in a pre-selected human language, and may transmit the response using the communication ports.

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