Development of Prevention Apparatus for Short-Circuit Faults Using the Line Voltage Drop of Neutral Wire

Abstract

-The major causes of electrical fire are classified to short circuit fault, overload fault, electric leakage and electric contact failure. The occurrence factor of the fire is electric arc or spark accompanied with such electric faults, specially short circuit faults. Earth Leakage Circuit Breaker (ELB) and Molded_case Circuit Breaker (MCCB), that is, Residual Current Protective Devices (RCDs) used on low voltage distribution lines cut off earth leakage and overload, but the RCD can not cut off electric arc or spark to be a major factor of electrical fire. As the RCDs which are applied in low voltage distribution panel are prescribed to rated breaking time about 30ms(KS C 4613), the RCDs can't perceive to the periodic electric arc or spark of more short wavelength level. To improve such problem, this paper proposes a prevention apparatus using the line voltage drop of neutral wire and some semiconductor switching devices. Some experimental tests of the proposed apparatus confirm the validity of the analytical results.

Development of Arc Fault Interruption Control Circuit of Fault Voltage Sensing Type

“…(5) , 최근에는 "과부하겸용 누전차단 기(RCD)"가 대중화되어 사용되고 있다. 그러나 이러한 MCCB, ELB, 그리고 RCD들은 누전사고나 과부하사고에 는 우수한 성능을 가지나, 순간단락사고나 접촉·접속불량 사고 등 전기화재와 밀접한 아크발생 사고에 대해서는 거 의 보호능력이 없는 것으로 분석된다 (6)(7)(8)(9) . 이는 순간단락사 고나 접촉·접속불량사고 등에 의한 아크전류 파형을 분석 해 보면, 아크의 폭이 약 5~10 ms, 진폭은 약 50~250 A로 추정되고 있어 이는 국내 규정으로 정해진 차단 동작시간 으로는 사고전류를 감지하기는 불가능한 이유이다.…”