There are three types of high-voltage power distribution devices:

The first is air-insulated conventional power distribution device, referred to as AIS. The busbar is exposed and in direct contact with the air, and the circuit breaker can be of porcelain column type or tank type. Gezhouba Power Plant adopts this type.

The second type is hybrid power distribution device, referred to as H-GIS. The busbar is open type, and the others are sulfur hexafluoride gas insulated switchgear.

The third type is sulfur hexafluoride gas insulated fully enclosed power distribution device. Its full English name is GAS—INSTULATED SWITCHGEAR, or GIS for short. The advantages of GIS are its small footprint, high reliability, strong security, and minimal maintenance workload. The maintenance interval of its main components is not less than 20 years.

Because C-GIS has the characteristics of small footprint, no influence from the external environment, and high reliability, it is increasingly used in petrochemical metallurgy, mining, development zones, urban rolling stock transportation, high-rise buildings, and high-altitude areas. Currently, the top eight foreign companies and their joint ventures that dominate the C-GIS market are ABB, Siemens, Areva, Malaysian TAMCO, South Korea's Hyundai Nanzi, and Japan's AE.

C-GIS has two types of structures:

Cylinder type and cabinet type. Cylindrical types such as Siemens' 8DA10/8DB10, Areva's WIA and WIB. The current structure is developing towards the cabinet type. For example, Siemens has developed cabinet-type 8DC11 and Nxplus models, and Areva has also developed cabinet-type GMA and WS types. Cabinet-type C-GIS accounts for about 70% to 85% of the total demand. In terms of the arrangement of its internal components, according to the relative positions of the busbar-isolation/grounding switch-circuit breaker, there are three arrangements: upper-middle-lower arrangement, lower-middle-upper arrangement and rear-middle-front arrangement. As a voltage level, there are mainly 12 kV level, 40.5 kV level, and 24 kV level; as a current carrying capacity, foreign C-GIS also has a rated current of 2500 A, while in China it generally reaches 1250 A, and some can reach 2000 A. ~2500 A; As the insulating medium, lower pressure SF6 gas is currently mainly used, but other gases have also begun to be used, such as dry pressure air, N2 and SF6+N2 mixed gas; as the components used, vacuum circuit breakers are currently mainly used. The isolating switch and grounding switch are made into a combined three-station isolating/grounding switch, and the busbar is made into a plug-in structure. As the air chamber, there are currently single air chambers, double air chambers and multiple air chambers. C-GIS is a high-tech product that often requires modern processing equipment, processing techniques and welding techniques, so it has high requirements for processing and manufacturing.