Leaks occur because the gaskets used in the equipment begin to leak as the gasket material deteriorates with age and use.
3 factors are important in gasket design:
- Hardening of the gaskets. High ambient temperatures and heat produced by the current passing through the circuit breaker in normal use affect the gaskets’ elasticity and harden them.
- Chemical attack. After years of use in substations, SF6 gas undergoes chemical changes as a result of arcing due to current interruptions. These short circuit interruptions change the composition of pure SF6 gas and partially decompose it.
- Corrosion. Filler material used in equipment seals is attacked by the external environment.
Two O-ring seals were located very closed together with a leak checking system between the two.Grease was used to protect against air borne pollutants.
Now we use 3 seals in one seal of a special shape. The main seal is protected from internal and external corrosion by two auxiliary seals. The seal is located in a groove designed to avoid any risk of scratching when the equipment is assembled, but the main seal now has a large surface to limit the risk of leakage if the metal gets caught in the seal assembly.