METHOD FOR PHASE COINCIDENCE CHECK IN THREE-PHASE NETWORK AND DEVICE FOR ITS IMPLEMENTATION Russian patent published in 2008 - IPC G01R19/00 

FIELD: electricity.

SUBSTANCE: inventions are attributed to electric engineering and intended for control of high voltage presence at power plant input and output and determination of line phasing correctness. Essence: power plant is checked for high voltage presence at input and output of electric unit. Then starting from the moment when voltage of one of the phases at power plant input or output differs from 0 but is less than its peak value, time period for each phase at input and output of power plant is selected which period is not divisible by voltage variation period of operative voltage network, and time period is measured for which voltages of three phases at power plant input and output have the same polarity. In case when time period coincides for each pair of voltages corresponding to one phase, it can be concluded that phases coincide at power plant input and output. Device for implementation of this method contains voltage variable capacitance transducers for each phase at collecting buses side. These transducers are connected with comparators outputs of which are connected with corresponding microcontroller inputs and microcontroller outputs are connected with indicator. At outgoing buses side voltage variable capacitance transducers are also installed. These transducers are connected with comparators the outputs of which are connected with corresponding microcontroller inputs and microcontroller outputs are connected with indicator. In microcontroller in one operation mode the presence of pulses and their repetition rate are determined and when pulse repetition rate corresponds to preset value the command is generated to turn on indicators. In the other mode of microcontroller operation, from the moment when phase voltage at power plant input or output exceeds 0 but is lower than its peak value the time period is selected which is not divisible by voltage variation period in operative voltage network and time is determined for which (in this device half-period is selected) voltages of three phases at power plant input and output have the same selected polarity. In case when time periods for each pair of voltages related to one phase are equal the conclusion is made that phases at input and output of power plant coincide with each other. When phasing is incorrect corresponding LEDs light up in sequence by pairs. These LEDs indicate which phases coincide.

EFFECT: improvement of check results accuracy and reliability, working personnel safety and maximal excluding of subjective evaluation during maintenance works in power plants.

5 cl, 2 dwg