Three post insulators for 1100kV GIL

The three pillar insulator used in 1100kV GIL is the core component of ultra-high voltage gas insulated metal enclosed transmission lines (GIL), and its technical level and performance directly affect the safety and stability of the entire transmission system. The following is a comprehensive technical analysis:
1、 Core Performance and Technological Innovation
Internationally leading insulation performance
The 1100kV three pillar insulator developed by our company adopts a multi-layer composite insulation structure, with a dielectric strength of ≥ 50kV/mm, a local discharge capacity of ≤ 5pC, a power frequency withstand voltage of 1200kV, and a lightning impulse withstand voltage of 1850kV
Through electric field temperature field fluid coupling simulation optimization, the problem of insulation margin reduction caused by gas convection under high load (8000A) was solved, and the discharge starting voltage was reduced by 11.6%
Mechanical and sealing reliability
Adopting a "three-phase common box" design, the mechanical strength can withstand 1.5 times the rated pressure water pressure test, and the interface stress is below 70MPa
The sealing performance meets the maintenance free requirement for 50 years, and the SF6 gas leakage rate is ≤ 0.1%/year
2、 Key Technologies and Applications
Structural optimization
The three pillar insulator adopts gradient material composite technology to suppress electric field distortion, and the maximum surface electric field strength is controlled below 15kV/mm
For risk points such as interface defects and internal bubbles, optimize the embedded design through COMSOL simulation. The defect width should be ≤ 0.1mm to avoid partial discharge
Typical application scenarios
It has been successfully applied to national key projects such as the Sutong GIL comprehensive pipe gallery project and the ultra-high voltage Wuhan station, with a cumulative delivery of over 5000 units
Suitable for high altitude, cold and harsh environments such as hydropower transmission, crossing mountains and rivers, with a transmission capacity of up to 5000MVA
3、 Industry Challenges and Development Trends
Gas convection effect
During high load operation, the conductor temperature increases by 53 ℃, resulting in a 15% decrease in SF6 gas density. Dynamic adjustment of the electric field design benchmark is required

Note: Customization with drawings is available