Lifetime prediction of a gas filling of an electrical switchgear

A method of predicting a lifetime of a gas filling 2 of an electrical switchgear 1, wherein pressure values p1, p2 in a system of the electrical switchgear containing the gas filling are measured at a predefined temperature Tp or at temperatures T1, T2 within a predefined temperature range, at different points in time t1, t2. Based on the pressure difference Δp between the pressure values the lifetime of the gas filling is calculated. The pressure of the gas filling may be measured using a capacitive pressure sensor 5 having an outer electrode 6, an inner electrode 7 and a dielectric material 8. The dielectric material may comprise an elastomer and the pressure can be calculated based on a volume change of the capacitor.