The factors affecting the temperature rise of the dense busbar slot mainly include the following:
1、The copper content of copper bars is low and the resistivity is high. Adults often mention the copper content and resistivity of copper bars, which are indeed related to the current-carrying capacity of the busbar. Copper bars with a copper content of 99.95% and a resistivity ρ ≤ 0.01777 (ohm*mm²/m) are relatively high-quality copper bars in the busbar copper bar. Due to the significant increase in copper prices in the market, some people use T3 copper (copper from waste cables), which has a low copper content and a high resistivity. In this case, the conductor size can only be increased to ensure the current-carrying capacity and the temperature rise. Otherwise, the temperature rise will be too high.
2、Insulation materials and shell structure have poor heat dissipation, and the structural process treatment is general. Some products have very poor heat dissipation in structure and insulation materials, and the conductors are selected according to the 30℃ ambient temperature in the electrical engineering manual. Some of these products can not achieve 100% of the current carrying capacity, which hides potential safety hazards and huge power losses in power distribution.
3、Late expansion overload operation. With the increase of later equipment, the load increases, or the original design busbar can not meet the needs of the later, using the capacity of the variable section without taking effective protection measures, resulting in high temperature when overloaded.
4、The connection head is not firmly connected, the connection bolt torque does not meet the standard, and the connection resistance increases; poor contact at the connection head and increased resistance can both cause the temperature rise of the busbar trunk to increase.
5、Skin effect. Inside the conductor, the heat generated by the resistance is not easy to dissipate, the temperature is high, the price and the rate of electronic operation are high, the line is not very flat, resulting in a relatively narrow electronic path, and the resistance is high. On the surface of the conductor, the heat dissipation is fast, the temperature is low, the price and the rate of electronic operation are low, the line is flat, resulting in a relatively wide electronic path, and the resistance on the surface of the conductor is small, and the electronic operation is faster. The heat generated by eddy currents or circulating currents causes the structure to heat up, increasing the temperature rise of the enclosed busbar shell.