Schweitzer Engineering Laboratories, Inc.

Pallavi Kulkarni

Marcos A Donolo

Anushka M Dissanayake

Veselin Skendzic

Angelo D'Aversa

Jay Hartshorn

Subhash C Patel

Vinod K Yedidi

Signal transducers in electrical communication with shorted leads of current transformers are used to provide monitoring and protection functions to an electric power delivery system. Differential protection is performed by comparing a predetermined threshold against a voltage signal from series-connected leads of signal transducers in electrical communication with shorted leads of current transformers. The signal transducers may be Rogowski coils. Signal transducers in communication with shorted leads may be used to improve safety and increase performance of the current transformers by decreasing susceptibility to saturation.

Differential protection using instrument transformer signal transducers

A system to reconfigure a motor from induction mode to synchronous mode at a zero crossing of the field voltage during startup using only stator current signals is described herein. The zero crossing may be detected by asymmetry induced in the stator currents by a current asymmetry inducing module of the motor. The current asymmetry inducing module may include a resistor and diode in series and in parallel with a discharge resistor of the field windings. Asymmetry is induced in the current obtained from the stator, and used to determine a zero crossing of the field voltage. Upon the rotor reaching a startup frequency and the detected zero-crossing of the field voltage, the motor may be reconfigured from induction mode to synchronous mode.

Synchronous motor startup configuration to synchronous mode at a field zero-crossing

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Pullman, WA, United States of America

Pallavi Kulkarni