50.以下哪一種保護裝置是基於測量故障點與保護電驛安裝點之間的距離來判斷是否需要跳機,並在輸電線路保護中被廣泛應用?(A)測距電驛(Distance Relay)(B)過電流電驛(Overcurrent Relay)(C)差動電驛(Differential Relay)(D)方向性功率電驛(Directional Power Relay)