The fuse cut-out and the pull-load fuse cut-out are outdoor high-voltage protective electrical appliances. They are installed on the high-voltage side of distribution transformers or on the trunk lines of distribution power lines, serving as short-circuit and overload protection for transformers and lines, as well as for the opening and closing of load currents. The fuse cut-out consists of two parts: an insulating bracket and a fuse wire tube. The static contact is mounted at both ends of the insulating bracket, while the moving contact is mounted at both ends of the fuse wire tube. The fuse wire tube is composed of an inner arc-suppressing tube and an outer phenolic paper tube or epoxy glass fiber tube. The pull-load fuse cut-out is enhanced with elastic auxiliary contacts and arc-quenching covers, used for opening and closing load currents.

The fuse tube closes in place when the fuse is tensioned during normal operation. In the event of a system fault, the fault current causes the fuse to quickly melt and form an arc. The arc heats the arc-extinguishing tube, causing it to decompose and release a large amount of gas, creating high pressure inside the switchgear. This pressure propels a longitudinal blast along the pipes, extending the arc and extinguishing it. After the fuse melts, the lower moving contact loses tension, flips downward, locks the mechanism, releases the fuse tube, and it falls to form a clear open position. When it's time to pull the load, an insulating rod is used to open the moving contact. At this point, the active and stationary contacts are still in contact. By continuing to pull the contacts with the insulating rod, the auxiliary contacts also separate, forming an arc between them. The arc is stretched in the arc-extinguishing cover slot, while the arc-extinguishing cover produces gas. At the moment the current passes through zero, the arc is extinguished.