Nr Electric Co., Ltd

Nr Engineering Co., Ltd

Nr Electric Engineering Co., Ltd.

Zigang Guo

Jun Chen

Kai Wang

Guang Wang

Qixue Zhang

Huazhong Li

Jiasheng Chen

Yaoyao Ji

Shouping Zhong

Yao Wang

The present invention discloses a method for detecting open phase of a startup/standby transformer based on optical CT. A startup/standby transformer in a power plant is in a no-load condition for a long time as a standby power supply. Once a single-phase open phase fault occurs, there is no significant change in the voltage phasor and voltage sequence component of each side. If not found in time, the defect may pose a great threat to the safe operation of the power plant. In the present invention, the optical CT is used to detect a three-phase current of the high-voltage side of the startup/standby transformer. If the current satisfies an open phase criterion, it is determined that an open phase fault occurs, and then, an alarm signal is given after a delay and an operator is informed to handle the fault in time. Therefore, the operation reliability of the startup/standby transformer system in the power plant is enhanced.

Method for detecting open phase of startup/standby transformer based on optical CT

A method and apparatus for identifying an open phase of a circuit breaker on the basis of voltage. The method comprises: a protection apparatus measures three-phase voltages at two sides of a circuit breaker; respectively calculates a vector difference and an effective value of the voltages at two sides of the circuit breaker; when the phase voltages at two sides are both greater than 80% to 90% of a rated voltage, and the voltage vector difference at two sides of the one-phase or two-phase circuit breaker is greater than a set voltage, it is determined that the circuit breaker has an open phase; and actuates an alarming or tripping operation after a short time delay t.

Method and apparatus for identifying open phase of circuit breaker on basis of voltage

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Jiangsu, China

Zigang Guo