| 摘要 |
PURPOSE:To simplify the structure and reduce the cost by comparing phases of voltage wave-forms generated by individual voltage dividers connected to shielding plates of vacuum breakers. CONSTITUTION:Voltage wave-forms generated by individual voltage dividers 12a-12c of multiple vacuum breakers 1a-1c, for example, arranged for individual phases are fed to phase regulators 19 and 20, the phase regulators 19 and 20 stagger the phases of other voltage wave-forms by preset phase angles against the phase of the reference voltage wave-form out of individual voltage wave-forms. Phases of the individual voltage wave-forms are applied to phase difference detectors 21-26, the phase difference detectors 21-26 compare the phases of the voltage wave-forms. When the phase difference detectors 21-26 detect the voltage wave-form having the phase difference against the phase of the reference voltage wave-form, a vacuum breaker generating this voltage wave-form is referred as defective vacuum. The structure is thereby simplified, the cost is reduced. |
