| 摘要 |
<p>A three-electrode-discharge surge arrester has two opposing discharging parts (12) of a pair of line electrodes (10), defining a gap therebetween, and a ground electrode (20) disposed between the two discharging parts and provided with a penetration hole (28) in the center. Each of the two discharging parts (12) has a substantially conical shape. In accordance with this substantially conical shape, each of inner surfaces (26) of upper and lower parts of the penetration hole of the ground electrode is substantially funnel-shaped. Hence, oblique parallel gaps (h) for a primary discharge are formed between the substantially funnel-shaped inner surfaces (26) of the upper and lower parts of the penetration hole and the two substantially conical discharging parts (12). Also, parallel gaps (H) for a secondary discharge are formed between peripheral parts (22) of the ground electrode around the penetration hole and peripheral parts (16) of the line electrodes. Each of the oblique parallel gaps (h) is formed narrower than each of the parallel gaps (H). <IMAGE></p> |
