| 摘要 |
PROBLEM TO BE SOLVED: To suppress increase of conductivity of arc and improve cut-off performance that does not relaying on usage of pressure rising in an arc-extinguishing chamber, by arranging a member containing fluorine in a region close to an arc generated when a fixed contact and a movable contact driven by a spring are released. SOLUTION: A magnetic driven core cover 11a for storing a magnetic driven core 12 for guiding an arc 10 generated in current cut-off to cooling plates 700 with a magnetic field between a fixed contact 401 and a movable contact 501, and side plates 701a for holding the cooling plates comprise fluororesin moldings. Fluorine gas generated by heating these with the arc 10 intrudes into the arc 10 and becomes a negative ion by bonding with an electron, temperature and conductivity of the arc is reduced, and arc resistance increases to decrease an arc current to improve current limiting performance. Therefore, active pressure rising in an arc-extinguishing chamber is not required, inexpensive material with less heat resistance and strength can be used for a case and a cover. A structure where coating containing fluorine is applied to the surfaces of the cooling plates 700 and the side plates 701a may be used.
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