ELECTRICAL ACTUATOR MEANS

摘要

The actuator includes a parallelepiped housing (2) having bolted on end covers (4, 6) through which extends a non-magnetic plunger rod (8) biassed by a spring (12). The plunger rod (8) carries a soft iron sleeve moveable within an electrical coil positioned adjacent the end face (4) and a permanent magnet array positioned centrally of the housing (2). The housing (2) is penetrated by a slot (28) accommodating a bus bar (30) carrying current to an associated circuit breaker having a fixed jaw (32) and a moveable jaw (34). In operation, the electrical coil is energised to augment the flux from the permanent magnet array to overcome the spring (12) and move the plunger rod (8) to a closed position, where it is held magnetically. Energising the electrical coil with the opposite polarity effects movement of the plunger rod (8) to an open or tripped position. Current flowing in the bus bar (30) produces a magnetic flux acting to reduce the hold-on force such that an overload will also effect tripping. Manual operation of the actuator may be effected utilising a lever arm (40) and linkage (42) acting on the plunger rod (8) and sleeve to cause a sufficient movement as to overcome the magnetic flux of the permanent magnet array to open the actuator or to overcome the spring (12) to close the actuator.