| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem, shown by a test for leading small current interruption, that when pre-arc is generated between contacts at application of currents, a melted part is generated on surfaces of the contacts, then the melted part is changed into a minute protrusion, and therefore high electric field is generated by voltage application so that withstand voltage performance decreases.SOLUTION: Two vacuum valves are connected in series; both of contact point pairs 59a of a first vacuum valve 50 are set movable; a contact, far from the first vacuum valve, of a contact point pair 86a of a second vacuum valve 80 is fixed and a contact thereof close to the first vacuum is set movable; a stud 60 close to the second vacuum valve is connected to a stud 88, connected to a movable contact of the second vacuum valve, so as to be movable together with the stud 88 and the other stud 61 is connected to an opening/closing mechanism 9, of two studs of the first vacuum valve; an open spring 74 is provided in the movable stud 88 of the second vacuum valve or the stud 60 of the first vacuum valve; and a resistor 40 is provided in parallel with the contact pair 86a of the second vacuum valve. |
