To provide an apparatus which can easily determine whether the state of the normal leak current of an electric path is in a range of being able to guarantee the detection accuracy of a requested grounding current for a resistor and also is practical and economical, relating to an apparatus such as a molded case circuit breaker, an earth leakage breaker, or a relay, which includes a means for detecting the ground leakage current of an electric path and detecting the magnitude of the leakage current due to resistor grounding, based on the phase difference between the magnitude and the voltage of the electric path.
The apparatus includes a means that detects the ground leakage current of the electric path and detects the grounding current for the resistor, based on the magnitude and the phase shift from the voltage of the electric path, thereby detecting the grounding current for the resistor having surpassed the specified magnitude. The apparatus includes a means that detects the normal leakage current together with the grounding current for the resistor and issues an alarm when the ground leakage current is over a value that is set according to the detection sensitivity of the grounding current for the resistor.
Nakada, Kenji
Imamoto, Masao
Aihara, Shigeru
Hayashi, Tadataka
Aoki, Takanori
Ando, Kenji
Higashida, Hironori
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