Answer: the line protection action can reflect a certain amount of the fault nature and scope, is briefly described as follows:
(1) if the current instantaneous fault protection movement, the nature of the fault is more serious, and occurs in the line head end.
(2)If a current I period of action, a fault line, and line head end range in protecting the installation place.
(3) if the over-current Ⅱ (Ⅲ) action, shows a fault line, and in full-length range, the focus is on the end.
(4) if the zero sequence protection action, the line of single-phase earth fault happened, the section is approximately the same action with over-current protection.
(5) high-frequency protection action, the single-phase grounding fault or alternate with line happened.
(6) distance protection action, the interphase short circuit fault happens, segmented action is about equal to the over-current protection.
(7) If with the direction of the protection action, the point of failure occurs within the line.
In determining the nature of the fault to determine the scope of the fault, ZMS cable agencies can based on the protection action in a comprehensive analysis of the fault wave record chart on the basis of a more accurate and rapid judgment.