Protective device

摘要

A protective device for protecting from abnormal voltage such as a lightning arrester comprises an earthing cylindrical metallic casing; an electrode or conductive substrate which is disposed to the direction of the axis of the metallic casing; an insulating pipe which is in spread-out shape and is disposed between the metallic casing and the electrode or the conductive substrate; and a plurality of non-linear resistors which are disposed in said insulating pipe wherein said non-linear resistors are respectively connected so as to be substantially similar to the potential distribution in said metallic casing.