| 摘要 |
A leak current breaker comprising a detecting section (10) for detecting a leak current from an electric line, a first removing section (12) for converting the leak current into a voltage and removing the harmonic components, a voltage detecting section (14) for detecting the voltage induced in the electric line (A), a second removing section (16) for removing the harmonic components included in the voltage, a phase difference detecting section (20) for detecting the phase difference from the signal waveform from which the harmonic components are removed, a frequency computing section (21) for computing the frequency of the electric line (A) from the signal waveform of the voltage from which the harmonic components are removed by the second removing section (16), a phase angle computing section (22) for computing the phase angle of the leak current from the electric line (A) from the phase difference and the frequency, an effective value computing section (24) for computing the effective value of the voltage from which the harmonic components are removed by the first removing section (12), a computing section (27) for computing the leak current component Igr resulting from the ground insulation resistance and included in the leak current flowing through the electric line (A) from the effective value and the phase angle of the leak current, a judging section (29) for judging whether or not the leak current competent Igr computed by the computing section (27) exceeds a given value, and a blocking section (30) for blocking the electric line (A) depending on the judgment. |
