Drop-out fuse cutout and load switching fuse cutouts are outdoor high voltage protection device. They are connected with the incoming feeder of the distribution transformer or distribution lines. These are primarily used to protect transformers or lines from short circuits and overloads and switching currents. The drop-out fuse unit is composed of insulator supports and a fuse tube, static contacts is fixed on two sides of insulator support and moving contact is installed on two ends of fuse tube. The interior of the fuse tube is the extinguishing tube, the exterior is made of phenolic compound paper tube or epoxy glass. Load switching cutout fuse provides stretch auxiliary contacts and arc-extinguishing enclosure for switching on/off loading current.
In normal operation the fuse link is tightened to form the closed position. In fault current situation, the fuse link melts and an electrical arc is formed. The arc-extinguishing tube is heated and explosion of gas occurs. This causes high pressure inside the tube and cause the tube to separate from the contacts. The strength of the contact is relaxed once the fuse elements melt.
The cutout is now in the open position, the operator needs to switch the current off. Then with an insulated operating bar, the moving contact can be pulled off. The main contact and auxiliary contact is connected.
It has small instant switch resistance,good steady rise property and it can reduce power grid's loss.
It has a property of reliable drop-out at any breakdown current.
It has safe antiseptic, antirust and acid proofing design, posses the property of reliable long-term stability operate function.
The fuse link has excellent property, high mechanic al strength, and strong arc-extinguishing capacity.