| 摘要 |
PROBLEM TO BE SOLVED: To solve the following problem:this protective device for a three phase motor has a contact mechanism by a stationary contact 6 and a movable contact 7 in a metallic enclosure, the movable contact 7 is disposed on a movable plate 8, the movable plate 8 is made rockable with a projecting piece part 8A supported by being inserted in the support hole of a support 10 as a fulcrum, the movable plate 8 is molded like a shallow plate and is driven by a thermally actuating board 12 reversing its bending direction by temperature to make break contacts, however, since the thermally actuating board 12 is operated by snapping action, there is possibility that arcing between the contacts continues by rebounding and bouncing caused by an impact at the time when making breaking the contacts. SOLUTION: The projecting piece part 8A forming the fulcrum of the movable plate 8 is held by an elastic body 14 to always and elastically press it against the inner surface of the supporting hole, and thereby, kinetic energy in the action of the movable plate is elastically decreased. Therefore, generation and continuation of rebounding and bouncing are suppressed, and durability of the protective device can be extended by suppressing contact consumption caused by arcing. COPYRIGHT: (C)2006,JPO&NCIPI
|
