What Is GIL?

GIL stands for Gas Insulated Metal Enclosed Transmission Line
① System composition
Cable system: mainly composed of cross-linked polyethylene cables, cable accessories, and grounding boxes.
GIL system: mainly composed of aluminum alloy shell, aluminum alloy conductor, SF6 insulating gas, and epoxy resin bracket.
manufacturing
Cable system: First, manufacture cables. The cable manufacturing process mainly relies on equipment control, making quality easier to ensure. Control the quality of raw materials and process flow to ensure relatively stable product quality. The structure of cable accessories is relatively complex. The core components rubber and epoxy resin require very high processing technology. Meanwhile, a complete monitoring process is needed to ensure quality. Especially for the installation of cable accessories, there is currently a high demand for the skill level of operators. Due to the fact that product components must be installed on the project site, the on-site environment is difficult to control, resulting in a high product failure rate.
GIL system: The main components of GIL include aluminum alloy shell and aluminum alloy conductor, which are processed products with relatively mature processing technology. SF6 insulating gas is a very stable and reliable insulating medium, and its performance is easy to detect. The oxygen pouring process is relatively mature and the product quality is controllable. Most of GIL's work is installed in the factory, reducing many uncontrollable factors on site.
The Economic Benefits of Applying GIL
Strong current carrying capacity can reduce the number of transmission lines in power plants and substations, and lower overall costs;
● Can solve the problem of limited spatial location and inability to use overhead lines in some special areas;
The design service life of reliable operation for 50 years far exceeds the expected service life of cable accessories, reducing overall costs;
The loss is much smaller than the loss of cables and overhead lines, accumulating economic benefits;
The laying method is flexible and convenient, which can reduce the distance between lines and lower the cost of civil engineering and mechanical and electrical engineering;
The single section pipeline unit is longer, and most of the work can be completed in the factory. The installation cycle is short, reducing installation and debugging costs;
Low maintenance and repair volume, high reliability, effectively improving the availability of power plants and substations.
Comparison of GIL and GIS Structures
GIL is equivalent to a longer GIS bus, and its structure is much simpler than GIS. Due to the length of the GIL line, factors that affect product quality have their own characteristics:
1. Thermal expansion and contraction are the key factors affecting the reliable operation of products;
2. It is necessary to effectively control the cumulative growth of machining accuracy deviation and assembly deviation;
3. Difficulty in surface treatment and cleaning inside the tube;
4. The on-site installation environment is complex.