| 摘要 |
<p>A CURRENT LIMITING CIRCUIT BREAKER A current limiting circuit interrupter having a movable contact arm disposed within a magnetic drive structure and a pair of contacts disposed within a magnetic arc driving structure is provided. The magnetic drive or slot motor rapidly moves the movable contact arm to separate the contacts upon a predetermined overload. When high overload currents pass through the contactor arm extremely fast separating movement occurs between the contacts providing current limiting. In one embodiment there is provided a pair of relatively stationary spaced apart contacts bridged by an elongated movable contact arm which can be moved away from the stationary contacts to establish two serially related arcs. At each end of the bridging contact there is provided a surrounding magnetic structure or yoke which magnetically impels any arc formed during circuit interruption to move laterally outward into an arc extinguishing structure. The arc extinguishing structure can comprise non-magnetic metallic spaced apart plates. The portion of the contact arm intermediate the ends is disposed within a magnetic drive or linear slot motor. The bridging contact arm is biased toward an open position by a spring and held in a closed position by a magnetic latch. When current exceeds a predetermined value the bridging contact arm is drawn into the slot motor rapidly opening the circuit interrupter. A plurality of T-shaped members are disposed partially within the magnetic arc driving yoke with the bottom portion of Tshaped member disposed in proximity to the contacts within the yoke opening. During circuit interruption the magnetic forces generated within the yoke rapidly move any arc formed off of the contacts into engagement with the bottom portion of the T-shaped plates. The portion of the T-shaped plates which contact the arc can be coated with tungsten for increased life. Since any arc formed during circuit interruption is moved rapidly off the contacts, the contacts can be formed from a material such as silver cadmium oxide, AgCdO, having a very low resistance.</p> |
