Working Principle Of Drop-out Fuses In Outdoor High-voltage Power Distribution

drop out fuse in transformer is an overcurrent protection device, which consists of three parts: an insulating support, moving and stationary contacts, and a fuse tube. The fuse tube includes an inner arc-suppressing tube and an outer phenolic paper tube or glass fiber cloth tube. This enables the drop out fuse price to operate quickly when the fault current exceeds the rated value.

The moving contacts at both ends of the fuse tube, with the tension of the fuse wire, push the upper moving contact into the "duckbill" protrusion and make tight contact with the upper stationary contact, forming a closed state. During normal operation, current can flow smoothly through the fuse tube. When a short circuit or overload occurs, the fault current causes the fuse to melt rapidly, generating an electric arc within the fuse tube. Under the influence of the arc, a large amount of gas is generated inside the fuse tube. This gas creates high pressure within the fuse tube and is forcefully ejected downwards, producing a strong deionization effect, ultimately extinguishing the arc when it crosses zero.

After the fuse melts, the moving contacts at both ends of the fuse tube lose the tension of the fuse wire. Under the combined action of the fuse tube's own weight and the upper and lower stationary contact springs, the fuse tube falls rapidly, breaking the circuit and disconnecting the faulty section of the line or equipment.