Challenges and impacts for maximum safety and accuracy
Most current conduction parts of high voltage switchgear, circuit breakers and transmission lines are mounted in pressure compartments filled with efficient insulation gases. Sulphur
hexafluoride SF6 gas is commonly used. Alternative insulation-gas mixtures, that are less harmful to the climate, steadily grow in market share. The insulation strengths of these gases depend basically on the gas density. As the dielectric strength capability of gas-insulated systems is obtained by the gas density, these compartments are filled to several hundred kPa pressure to prevent internal arcing and short circuits even over short distances.
Gas density monitoring plays a key role in plant availability and safety
The operational reliability and safety of high-voltage gear is only guaranteed when the appropriate level of gas density is maintained within the compartments. Leakage would compromise the safety of the switchgear and violate environmental regulations. SF6 is a strong greenhouse gas and must therefore not leak into the environment. Strict regulations regarding SF6 emissions (e.g. F-gas Regulation 517/2014) must be met and stipulate a permanent monitoring of gas leakage. This is done with gas density monitors or gas sensors to trigger safety related alarms or switching processes and to transmit the status to a data network.
Therefore, continuous density measurement adds several advantages to monitoring of safety alarm trigger points. Real time data allows analysis of the operational availability of the plant and the implementation of inspection windows or predictive maintenance measures.