The Impact Of Flammable Insulating Material Fire On Cable Terminal Performance

In industrial and building electrical systems, wire lugs serves the dual function of providing electrical power and mechanical connection. Insulation materials are an essential component of cables and the area surrounding electrical lugs terminals, and their performance maintains good dielectric isolation and mechanical protection under normal operating conditions. However, when the surrounding or its own combustible insulation materials are ignited, the terminal lugs status will change significantly, affecting system operation and safety level.

Thermal Impact Mechanism and Changes in Electrical Characteristics

Once flammable insulation materials ignite, a high-temperature environment rapidly forms. During combustion, these materials decompose and release heat, raising the temperature of nearby cables and terminals. The effects of high temperatures on terminal contacts include material softening, accelerated oxidation of the contact surface, and thermal expansion of the metal. These changes alter the resistance and electric field distribution at the terminals. With continued thermal stress, the contact resistance between the terminal and conductor may increase, leading to an increased risk of localized overheating and arcing. High-temperature environments can also damage the insulation seal of terminals, reducing electrical insulation levels and increasing the risk of dielectric breakdown.

Structural Degradation and Long-Term Reliability Impacts

• Material Degradation: The heat and decomposition products released by combustible insulating materials impose chemical and thermodynamic burdens on the insulation support structure of the copper lugs terminal, accelerating the aging of plastic or rubber components.

• Decreased Contact Stability: Temperatures exceeding the design thermal limits of metal components and high-temperature cycling can cause connector loosening, reducing mechanical clamping force and affecting long-term conductivity.

Decreased Dielectric Strength: Combustion products may deposit on the surface of terminals and cables, forming conductive or semi-conductive paths, leading to reduced dielectric strength and increasing the risk of leakage current.

Surface Discharge and Flame Spread Risks

In combustion scenarios, the thermal decomposition and combustion process of combustible insulating materials alters the surrounding electric field distribution. When poor contact occurs at the Aluminum Cable Lug terminal or uneven heating occurs on the terminal surface, partial discharge is more likely to occur, even without external short-circuit induction. This discharge phenomenon can cause electrochemical corrosion of the terminal metal components and may also promote further flame spread, creating greater safety hazards.