Common Faults of GIS
The advantages of GIS equipment, such as high operational reliability, low maintenance workload, and long maintenance cycle, have been demonstrated. However, some faults have occurred successively, mainly manifested in the following aspects:
SF6 gas leakage
Such faults usually occur at the sealing surfaces, welding points and pipe joints of the combined electrical apparatus. The main reasons are that the sealing gaskets have aged or there are sand holes in the weld seams. Therefore, a large amount of SF gas needs to be replenished for GIS every year to ensure the normal working pressure. Such faults are quite common.
2. Excessive moisture content in SF6 gas
The micro-water content of the SF6 gas in the circuit breaker compartment should be ≤ 300×10-6, and for other compartments, it should be ≤ 500×10-6. Excessive SF6 gas moisture can cause faults that lead to flashover of insulators or other insulating components. The main reason for excessive micro-water content is the water that leaks through the sealing components and enters the SF6 gas. After many years of operation, the continuous increase in the moisture content in the gas is undoubtedly the result of external water vapor penetrating into the equipment from the outside. Water molecules have a V-shaped structure, and their equivalent molecular diameter is 0.7 times that of the SF6 molecule. Therefore, the water has extremely strong penetration power. Moreover, the water vapor pressure in the atmosphere is usually dozens or even hundreds of times higher than the water pressure in the equipment. Under this pressure, water from the atmosphere will gradually penetrate through the sealing components into the gas-insulated equipment.
3. Switch malfunction
Gas breakdown of components such as circuit breakers, load switches, disconnectors or grounding switches. Also, the moving and static contacts deviate during the closing process, resulting in poor contact.
4. Internal Discharge in GIS
Due to manufacturing process reasons, certain components within the GIS are at an elevated electric potential, resulting in a local increase in electric field strength and subsequently causing corona discharge. The presence of metal impurities in the GIS and bubbles in the insulators can both lead to the occurrence of corona discharge or local discharge.
5. The hydraulic mechanism experiences oil leakage or frequent pressure-holding operations.
Most of these failures are caused by the aging of the hydraulic mechanism’s sealing rings, or by the misalignment of the installation position, or by nitrogen leakage from the pressure storage cylinder. Such failures are quite common in GIS systems.
Post time: Mar-02-2026