FIELD: electricity.
SUBSTANCE: since occurrence of fault current surge the countdown is started, which is equal to the delay time of the MCB protection actuation at that monitoring presence of fault current, and when fault current disappears upon completion of the above countdown then the conclusion is made on the MCB closure; upon disconnection of fault current the parameters are measured in the line by sounding pulses sent to all the line wires, the time of signals passing to all reflection points and distances are measure and the parameters are compared with parameters of the normal mode received in similar way in normal operating conditions, and when upon disconnection of fault current till completion of the countdown the parameters are different from the parameters in normal mode, the conclusion is made that short circuit is not self-repaired, the prohibition is set for automatic reclosure of the MCB and measurement of the parameters in the line and their comparison with the normal mode parameters is continued, and when at any moment before ending of the protection operation delay time with speedup plus the MCB switchover delay time for the second cycle the compared parameters are similar, the conclusion is made that short circuit is self-repaired, the prohibition signal is lifted and when at the moment of completion of the MCB switchover delay time for the second cycle surge of operating current appears in the line, then conclusion is made about successful reclosure of the MCB in the line during the second cycle of automatic reclosure.
EFFECT: expanded functionalities due to prohibition of automatic reclosure of the MCB in the line during the first cycle with subsequent successful reclosure during the second cycle.
2 dwg
