| 摘要 |
A multipolar circuit breaker having a lower case portion with side frame plates and a central frame plate facing the side frame plates on its two major sides, the central frame plate having a deep central groove which forms two flexible central frame plate arms each facing one of the side frame plates to form a nacelle sized to receive one of the switching mechanisms, each of the side frame plates and the arms of the central frame plate having, proximate to its free end, at-least-one inwardly facing protrusion, each of which is in a position opposed to the corresponding protrusion on the companion plate forming the nacelle and, after the respective switching mechanisms are installed, overlapping the side plates of each of the switching mechanisms, the arms of the central frame plate having been deflected to permit insertion of each switching mechanism, deflection in testing or use being prevented by inserting a high dielectric strength plastic stiffener in the groove separating the arms in the central frame plate, the lower case side frame plates having on their outer surfaces near the base of the lower case portion at-least-one retainer protrusion which cooperates with properly positioned openings in the upper case portion when that portion is in position covering the sides and top of the lower case portion to hold the upper case portion removably in that position, as a result of all of which the switching mechanisms may be checked for defects during production without assembling and then disassembling the circuit breaker.
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