Our country's ultra-high voltage power grid includes two forms: ultra-high voltage alternating current transmission and direct current transmission. The alternating current is 1000 kilovolts, and the direct current is ±800 kilovolts. Based on the characteristics of future power flow and load center distribution in our country, as well as the features of ultra-high voltage alternating current transmission and ultra-high voltage direct current transmission, in the construction of our country's ultra-high voltage power grid, 1000 kilovolt alternating current ultra-high voltage transmission will be the main form to form the national ultra-high voltage backbone grid, so as to achieve synchronous strong interconnection of various regional power grids; ±800 kilovolt ultra-high voltage direct current transmission will mainly be used for long-distance, without intermediate drop points and without voltage support, large-power transmission projects. When the voltage on the conductors and hardware is very high, the potential gradient on the surface exceeds the critical value, and visible corona will be generated. 

The surface air undergoes ionization under the excessive potential gradient, emitting a blue glow and making a sound. This is the phenomenon of corona discharge. The hazards of corona discharge are as follows: Firstly, it consumes energy and causes power loss. Secondly, it generates radio interference, with a strong interference intensity at frequencies of 0.5 to 1.5 MHz. To control corona discharge and reduce its harmful effects, it is particularly important to install such protective fittings on the lines. Fittings, including clamps, hanging plates, and bolts, are all angular components. For lines above 220 kV, without installing shielding rings, the high potential gradient at the tip of the fittings will generate intense corona. 

Equalizing current shielding hardware is a common type of electrical protection hardware. The most commonly used ones are equalizing rings and shielding rings. Currently, the equalizing shielding rings for the conductors and tension insulator strings of 500kV transmission lines in China are generally ear-shaped rings. These ear-shaped rings are usually placed beside the tension insulator strings and the hardware including line clamps, hanging plates, and bolts. They have both equalizing and shielding functions, so they are called equalizing shielding rings. When ring-shaped or runway-type equalizing rings are used in ultra-high voltage transmission lines, because ring-shaped or runway-type equalizing rings only have the equalizing effect on the tension insulator strings, they cannot simultaneously provide shielding against corona for the hardware in the ultra-high voltage lines. Therefore, a separate shielding ring needs to be set up to shield the hardware in the ultra-high voltage transmission lines. 

In overhead line engineering, ultra-high voltage shielded components protect insulators and line hardware, controlling the visible corona discharge that occurs when the voltage is very high. With the development of the economy and the increase in domestic voltage levels, the harmfulness of corona discharge has been increasingly emphasized. The function of the equalizing shield ring cannot be underestimated. The equalizing rings, shield rings and equalizing shield rings used in China are made of pure aluminum. The support frame and the ring body are welded together and connected to the corresponding shielded body through fasteners. In engineering use, the welding workload is large. Examples of insufficient strength due to welding point defects have occurred repeatedly, posing significant safety hazards and causing serious economic losses.