| 摘要 |
PURPOSE: A ground fault over current relay and operating method thereof can block power application to a load instrument if it is decided as a ground fault accident. CONSTITUTION: Input current is sensed, and an input current value is produced (S120). Whether performing blocking mode for relay operation is determined if the input current value is equal to or more than a predetermined reference current value (S130). Input voltage is sensed, and an input voltage fluctuation rate is produced if blocking mode is determined to be performed (S140). The blocking mode is cancelled if the input voltage fluctuation rate is equal to or more than a predetermined reference voltage fluctuation rate (S160). The blocking mode is cancelled by comparing an execution time of the blocking mode with a predetermined reference time if the input voltage fluctuation rate is smaller than the predetermined voltage fluctuation rate. [Reference numerals] (110) Current detection unit; (120) Voltage detection unit; (130) Judgment unit; (140) Control unit; (150) Motion unit; (160) Timer; (300) Load device |
