NAL switch disconnector and NALF fuse switch disconnector, designed by ABB, they are high voltage switch disconnectors combined air-blast arc extinction with aerogenesis arc extinction.

By combining NAL switch disconnector with fuse, the fuse switch disconnector possesses both advantages. NAL switch disconnector disconnects any load currents until its rated breaking current, the fuse and its striker break any over-load current until any fuse switch disconnector’s rated short-circuit breaking current. NAL switch disconnector and NALF fuse switch disconnector are largely used as transformer switch in distribution networks, motor switch or capacitor switch.

Basic structure and operation mechanism

NAL switch disconnector - Consists of the body of switch disconnector and K-type spring operation mechanism. Its rated current is 630A or 1250A. K-type operation mechanism is single-spring operation mechanism which makes the switch disconnector close and open.

NALF fuse switch disconnector - Consists of the body of 630A switch disconnector, A-type spring operation mechanism, fuse tripping mechanism, fuse and fuse base etc among which the fuse is optional and its max. rated current is 1250A. A-type operation mechanism is dual-spring operation mechanism that the opening spring should be stored energy before opening operation.

The fuse tripping mechanism works with the A-type operation mechanism. When the fuse melts, the fuse striker strikes the tripping mechanism and drives it to make the A-type operation mechanism work to open the switch. If the damaged fuse is not replaced, the A-type operation mechanism cannot work, the switch cannot close.