From generation to consumption, electric energy goes through five links: power generation, transmission, transformation, power distribution, and electricity consumption. Generally, the larger the machine assembly capacity, the higher the generator outlet voltage. In the transmission and distribution link, the current highest AC voltage level in my country is 1000kV (Changzhi-Jingmen line), and the highest DC voltage level is ±800kV (Xiangjiaba-Shanghai, Jinping-Sunan UHV DC). 500kV, 330kV, 220kV, 110kV, 66kV, 35kV, 10kV, 380/220V, of which 60kV is left over due to historical reasons and only exists in northeast my country. Generally, voltage lines above 35kV are called transmission lines, and voltage lines below 35kV are called distribution lines.