| 摘要 |
PROBLEM TO BE SOLVED: To prevent a short-circuit plug from pulling out of an electrode pair in a state of a main circuit being closed. SOLUTION: When a lever 22 is turned in opening a main circuit, a guided part 27 passes by a linear guide part 17 with excess of speed and gets insertion- coupled with an over-stroke part 17C and detachment of a short circuit plug is controlled, so the lever has to be returned until the guided part 27 is positioned at the linear guide part 17A. Therefore, it takes time from the time when the relay circuit begins an opening operation with the turn of the lever 22 till the short circuit plug 20 is pulled out of the electrode pair 12, so that, even if there is a time lag between the beginning of the opening operation of the relay circuit and the opening of the main circuit, there is no risk of the short-circuit plug pulled out of the electrode pair with the main circuit in a closed state.
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