Transient Voltage Challenge: Analyzing The Physical Losses And Structural Impacts Of Arc Reignition On Fuses

In circuit protection systems, the interruption of fault current by the drop out fuse is not instantaneous. After the molten metal vaporizes upon heating, the plasma channel formed between the contacts becomes the electric arc. If the dielectric strength recovery rate lags behind the rise rate of the transient recovery voltage (TRV), the extinguished arc can reignite in the gap. This phenomenon directly interferes with the expected operation of the protection device, increasing the operational risk of the power system.

Transient recovery voltage rise leading to fuse dielectric breakdown

Arc reignition is essentially a secondary damage to insulation properties. When the fuse attempts to cut off the circuit at the current zero-crossing point, the metal vapor and high-temperature gas inside the cavity have not yet completely diffused. If the residual voltage of the system exceeds the current gap's withstand limit, the discharge channel will reopen. This cycle prolongs the duration of the fault current, subjecting the internal insulating dielectric to thermal stress far exceeding design specifications.

Arrow channel heat accumulation leading to arc-extinguishing dielectric degradation

• Quartz sand vitrification: The quartz sand filling the fuse extinguishes the arc by melting through heat absorption. The secondary high temperature generated by reignition causes excessive vitrification of the sand particles, forming Joule channels with some conductivity, weakening insulation.
• Intracavity pressure surge: Repeated reignition leads to an exponential increase in internal pressure within the sealed tube, placing extremely high demands on the shell strength.
• Metal plate ablation: Repeated arc impacts accelerate the vaporization of the contact material, altering the original physical spacing and causing a decrease in arc extinguishing characteristics.

Failure modes of fuse insulation structure under frequent reignition:

Severe arc reignition can induce mechanical damage or arcing in the fuse. When the arc cannot be completely extinguished within a finite period, electrical energy continues to be converted into heat energy, and the shell material is prone to cracking under high temperature and high pressure. Once the arc splashes onto external metal components, it may cause large-scale phase-to-phase short circuits. This chain reaction directly weakens the overall reliability of the power distribution system.

Technical matching solutions for reignition:

Fuse selection must be precisely matched to the inductive load characteristics of the system. For environments with large inductive energy storage, selecting protection components with higher voltage redundancy can reduce the probability of breakdown. Matching a low transient voltage rise rate (RRRV) is a direct means of suppressing reignition. Regularly monitoring the compaction and dryness of the arc-extinguishing filler helps maintain a stable dielectric recovery curve, ensuring long-term line safety.