Understanding The Reaction Mechanism Of Drop-out Fuses

In power distribution systems, expulsion drop out fuse is a widely used high-voltage line protection device. Its design logic is rooted in the thermal effect of current on the fuse material, a mechanism that allows for rapid activation upon fault occurrence. fuse drop out typically consists of components such as insulating supports, dynamic and static contacts, and fuse tubes. Under normal system conditions, the fuse tube and contacts maintain a closed circuit, allowing current to flow steadily.

When an overcurrent or short-circuit fault occurs in the line, the fuse melts due to a rapid increase in current. An electric arc within the fuse tube heats the surrounding medium and generates a large amount of gas. During this process, pressure changes and gas action cause the arc to elongate and eventually extinguish, meaning the circuit connection point will disengage due to the loss of fuse tension. As the fuse tube falls to a clearly open position under gravity, current flow ceases, breaking the circuit.