Arc Phenomenon At The Moment The Fuse Element Breaks

During the liquefaction and vaporization of molten metal, an electric current continuously flows through the molten metal vapor. The electrodynamic force generated around the melt creates a contraction effect, causing the liquefied or vaporized conductive medium to contract and collapse inward. This contraction effect induces the molten metal to fracture, forming a tiny gap between the two electrodes.

When the drop out fuse melt just breaks off, the electric field strength between the electrodes increases sharply. Since the gap is still subjected to the power supply voltage and the induced voltage of the circuit, the strong electric field immediately breaks down the gaseous medium within the gap. Electrons on the cathode surface are pulled out under the influence of the strong electric field, forming a free electron stream. These high-speed electrons collide with gas molecules, ionizing them and generating more electrons and positive ions, ultimately leading to the breakdown of the gas and the formation of a conductive path.

The high-temperature metal vapor generated during the melting process rapidly diffuses within the gap. The metal vapor contains a large number of easily ionized particles, which undergo thermal ionization under the applied voltage. The temperature in the arc column region can reach thousands of degrees Celsius. In such a high-temperature environment, the thermal velocity of gas molecules increases significantly, making them more prone to ionization upon collision, thus maintaining the continuous combustion of the arc.