Ukk Junction Box Thermal Runaway Analysis: The Impact Of Current Carrying Limit On Insulation Life

Heat accumulation inside the electrical cabinet stems from incorrect connector selection. If the actual load exceeds the nominal limit, the connectors may experience uncontrolled temperature rise, leading to physical deformation.

Thermal aging mechanism triggered by current overload

When the circuit operating current exceeds the design specifications, a large amount of Joule heat will accumulate in the internal conductive components of din rail power distribution terminal blocks. Heat is continuously conducted to the casing, and if the current carrying capacity is insufficient, the insulation material of the power distribution block 4 pole device may age. This phenomenon is particularly pronounced under prolonged full load or instantaneous surge impact, manifesting as a darkening and brittleness of the polyamide casing, resulting in a loss of its original mechanical strength.

The evolution of performance degradation

When the material is exposed to continuous high temperatures, the molecular chains break down, and the electrical isolation capability of din distribution block decreases accordingly. Specific manifestations include:

• Thermal expansion and contraction of metal clamps reduces contact pressure.

• Conductive paths are created on the insulator surface due to high-temperature carbonization.

• Decreased dielectric strength induces the risk of partial discharge.

System maintenance personnel should monitor the real-time operating temperature of the electrical power distribution blocks using infrared thermal imaging to prevent extreme operating conditions from damaging the circuit stability of the power distribution system.