| 摘要 |
PROBLEM TO BE SOLVED: To provide a ground directional relay capable of variably setting an optimum sensitivity angle determining the direction of a ground fault, and setting appropriate operating characteristics to a system to be installed. SOLUTION: A computing module 18 computes an operating basic setting value based on ground current determined by simulated perfect ground test and ground current, or computes and sets the operating basic setting value based on information set by an external setting module 16. The operating basic setting value is an optimum sensitivity angle indicating the directional element of a ground fault and minimum operating current indicating a ground overcurrent element. The computed operating basic setting value is set by a fault detecting module 14. The fault module 14 compares a phase difference in the ground current and ground voltage detected from an electric power system and ground current value with a basic setting value for ground detection.
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