| 摘要 |
PROBLEM TO BE SOLVED: To facilitate drive of an arc on an electrode surface and to attain improvement in a cutoff performance and the number of times of cutoff and downsizing by preventing an electric field from being concentrated.SOLUTION: An electrode is formed from a spiral part 11b and a linear part 11a. In the spiral part, an electrification part 18 and a current path control part 11 are disposed in a radially outside portion of an electrode rod insertion part 17, and the current path control part 11 spirally extends from the electrode rod insertion part 17. The linear part spirally extends from a distal end of the spiral part 11b. The electrification part 18 is a region between the current path control parts 11 that are neighboring to each other in a circumferential direction, and is formed from an outer peripheral ring part 18a that is an outer peripheral portion and a current induction part 18b that is an inner peripheral portion.SELECTED DRAWING: Figure 2 |
