DISTRIBUTION PROTECTING SYSTEM

PROBLEM TO BE SOLVED: To swiftly detect accident that has occurred in a distribution system and trip a switchgear which is installed on the power supply side of the point of the accident and nearest the location of the accident. SOLUTION: Each of switchgears is formed by installing an interrupt part of a three-phase structure and a circuit breaking part in a case, connecting them with distribution lines via bushing penetrating respective sidewalls, placing a current transformer (CT) 8 in two of three phases at one end of the series- placed portion of the interrupt part 1 of three-phase structure or the interrupt part 1 and the circuit breaking part 2, placing a zero-phase current transformer (ZCT) 9 at the other end of the series-placed portion of the interrupt part 1 or the interrupt part 1 and the circuit breaking part 2, and placing a voltage divider 5 for every phase at both the ends of the series-placed portion of the interrupt part 1 or the interrupt part 1 and the circuit breaking part 2.