The maximum allowable current carrying capacity of each conductor is specified in the national code. When in use, the maximum load current required by the load must be less than the long-term allowable current carrying capacity of the conductor in the air.
For example, the long-term allowable current carrying capacity of 25mm2 copper core wire in air is 105A. When the main equipment is running, the running current can only be less than or equal to 105A and never greater than 105A.
Using extended data to analyze the internal factors affecting the current carrying capacity of cables;
The nature of the conductor itself is the internal factor that affects the current carrying capacity of the cable. Increasing the core area, using highly conductive materials, using insulating materials with good heat resistance and reducing contact resistance can all improve the current carrying capacity of cables.
1. Increase the core area and increase the current carrying capacity of the cable.
The core area (conductor cross-sectional area) is positively correlated with the current carrying capacity. Generally, the safe current carrying capacity of copper wire is 5~8A/mm2, and that of aluminum wire is 3~5A/mm2.
2. Use highly conductive materials to improve the current carrying capacity of cables.
If copper wire is used instead of aluminum wire, the download flow of the same specification can be increased by 30%. Silver wire is even used in some demanding occasions.
3. Use insulating materials with high temperature resistance and good thermal conductivity to improve the current carrying capacity of cables.
Although the temperature resistance of insulating materials can reach above 100℃, considering the actual laying conditions and safety, the allowable temperature will be reduced, and the situation varies from country to country.
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