| 摘要 |
2232 The commutator switch has a fixed contact, a movable contact and an associated arc extinction chamber. The moulded case encloses an operating mechanism (14) linked to that of the other poles by a transverse rotatable bar (16), coupled (54) in each unit to a moving contact assembly (60/64). When closed, this is forced by springs (52) against a fixed contact (28/30) assembly. Each assembly includes main current-carrying contacts, and an arcing contact, arranged to open slightly later than the latter when the circuit-breaker opens. The arc thus struck is centrally located in front of the arc extinction chamber (24). Contacts are connected to the unit's terminals along the underside of the case (20;49;40). The fixed arcing contact (30) is integral with an arcing plate (34) covering the insulated floor of the extinction chamber. A series of regularly spaced flat metal separators, parallel to this floor, is installed between this arcing plate and a top arcing plate (96), bent down (98) at the front to be close to (99) the moving arcing contact (60) when opening is complete. Separator front edges are alternately notched to left and right of center, the plates extending laterally and rearwards to the chamber sides and back, the latter perforated to relieve gas pressure. Insulating side-wings, e.g. of PTFE, restrict the chamber entry, much more at the top than near the bottom.
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