Are SF6 gas circuit breakers reliable?

The reliability of the equipment cannot be determined solely by its age, as its actual condition is influenced by wear and the maintenance it has received. This document identifies the areas of deterioration, emphasizing the need for preservation measures, and establishes their defined limits for SF6 gas circuit breakers.

Do non-sf6 gases affect mechanical wear of circuit breaker designs?

If applicable, the impact of non-SF6 gases or gas mixtures on mechanical wear of different circuit breaker designs (e.g. CO2-breaker, vacuum breaker) has to be discussed between the end user and the equipment manufacturer. The following diagnostic techniques may be helpful in assessing residual life:

Does SF6 gas decompose at high temperatures?

For GIS with SF6 gas: SF6 gas begins to decompose at high temperatures and the techniques described below for monitoring decomposition products may reveal the presence of a hot contact within a gas compartment.

Can partial discharge detect voids in SF6 insulated systems?

In their work on the long term performance of SF6 insulated systems, Task Force observed that partial discharge measurement may be able to detect voids in solid insulation, provided sufficient sensitivity can be achieved and pulsed discharge activity occurs.

What causes SF6 leakage?

SF6 leakage may be an indication of flange corrosion. The material used for the sealing function must be able to provide sufficient gas tightness over the lifetime under application conditions. Main factors causing ageing are the material used, temperature, UV radiation, exposure to oxygen and their combination.

Can SF6 be used for HV GIS?

Other defects may only be detected by visual inspection. 4- High-speed earthing switches: For HV GIS, high speed earthing switches have the duty to make rated short circuit currents for at least two times, and to switch rather small induced currents. Thus, they are usually unlikely to be the life limiting factors of HV GIS with SF6.