Factory power supply system refers to the circuit system from the power line entering the factory to the incoming terminal of high and low voltage electrical equipment, including the substation and all high and low voltage power supply lines in the factory.

The task of substation is to receive and distribute electric energy without changing voltage; The task of substation is to receive electric energy, convert voltage and distribute electric energy.

High-voltage direct distribution goes deep into the load center, which can save the first-stage intermediate transformation; It simplifies the wiring of power supply system, saves investment and nonferrous metals, reduces power loss and voltage loss, and improves power supply quality. However, it depends on whether the environmental conditions of the factory meet the requirements of "safe corridor" for 35KV overhead lines to penetrate into the load center, otherwise it is not suitable.