Method for determining a gas quantity in an insulated switchgear

A method for determining a quantity of a gas contained in a tank of a gas insulated switchgear, the tank comprising a gas temperature sensor and a gas pressure sensor, the method comprising the following during a calibration phase:

• (i) acquiring a first temperature and a second temperature measured by the gas temperature sensor respectively at a first instant and at a second instant,
• (ii) acquiring a first pressure and a second pressure measured by the gas pressure sensor at the first instant and at the second instant,
• (iii) determining a steady-state model of the tank thermal exchanges from the first and second acquired temperatures and from the first and second acquired pressures,
• the method further comprising the following during a measurement phase:
• (iv) acquiring a gas temperature measured by the gas temperature sensor,
• (v) acquiring a gas pressure measured by the pressure sensor,
• (vi) acquiring an ambient temperature measured by an ambient temperature sensor outside the tank during the measurement phase, and
• (vii) determining the quantity of the gas from the acquired gas temperature, the acquired gas pressure, the acquired ambient temperature and the determined steady state model.