Smart middle sensitive Earth Leakage BreakerELB and Smart Earth Leak detectorELD included Current Phase Change Detector Frequency Counter and a Elimination Circuit of Transient Leakage Current not to operate a unnecessary operation preventing function

摘要

The present invention relates to a medium-sensitive earth leakage breaker and earth leakage detector and, more specifically, to a smart medium-sensitive earth leakage breaker and smart earth leakage detector including a current phase change detector, a frequency counter, and an elimination circuit of a transient leakage current therein and capable of preventing an unnecessary operation on a leakage current detected due to an instantaneous change in a load-side current phase of the leakage current detected by a zero current transformer (ZCT) as an electromagnetic switch (magnet switch) operates. To this end, provided are a smart medium-sensitive earth leakage breaker and smart earth leakage detector including a current phase change detector, a frequency counter, and an elimination circuit of a transient leakage current therein and capable of preventing unnecessary operation, wherein the smart medium-sensitive earth leakage breaker and smart earth leakage detector comprises: the current phase change detector configured to suppress an operation of the earth leakage breaker when a phase change equal to or greater than a set value of a current waveform is detected from an output current of a current converter in a three-phase power system; the frequency counter configured to suppress an operation of the earth leakage breaker when a harmonic is detected due to an instantaneous change in a current phase of the leakage current from the ZCT; and the elimination circuit of a transient leakage current configured to suppress an operation of the earth leakage breaker when the transient leakage current is detected due to the instantaneous change in a current phase of the leakage current from the ZCT.