Arc Movement Mechanism Of Fuse: Structural Design Of Arc Migrating Downward Inside The Fuse Tube
Under overcurrent or short-circuit conditions, the internal melt of drop out fuse heats up rapidly and melts, generating an electric arc the instant the current path is broken. After the arc forms, the internal structure of the fuse tube begins to guide the arc's movement. Fuses typically employ specific structural designs to gradually elongate the arc within the fuse tube and move it towards the bottom, thereby altering the arc's shape and reducing the likelihood of sustained arcing. The fuse tube material is often a gas-generating insulating material. When the arc contacts the tube wall, gas flow is generated, which propels the arc, causing it to migrate axially within the fuse tube.
The Influence of Fuse Tube Structure on Arc Movement
The movement of the arc towards the bottom of the fuse tube depends on the internal spatial structure and material properties of the fuse tube. Fuse tubes are typically made of epoxy fiberglass or gas-generating fiber materials. When the arc generates high temperatures and contacts the tube wall, the material decomposes, releasing gas. This gas forms a directional airflow within the fuse tube, propelling the arc towards the bottom. As the arc path gradually lengthens, the arc voltage increases synchronously, and the conductive path gradually weakens.
The fuse also contains filler or arc-extinguishing media, such as quartz sand particles. The granular structure divides the arc into multiple short segments, dispersing the arc column's energy. The arc column extends within a narrow channel, eventually concentrating towards the bottom of the fuse tube. This structural design is a typical arc control method, widely used in both low-voltage and high-voltage fuses.
Energy attenuation during arc migration
This causes the arc to move towards the bottom of the fuse tube, a process accompanied by arc length growth and temperature changes. As the arc extends inside the fuse tube, the arc column remains in continuous contact with the arc-extinguishing media, compressing and splitting the arc path. The arc resistance gradually increases, and arc energy is absorbed by the filler particles and the tube wall surface.
The fuse design also utilizes a longitudinal arc-blowing structure to create a stable arc movement trend within the tube. The arc column moves away from the fusible breakage area, further weakening the arc path. As the arc current decreases, the arc gradually disappears, and the circuit breaks. This arc motion control method constitutes an important part of the arc extinguishing mechanism of fuses and has fundamental significance in the design of power distribution protection equipment.
