Mixture of decafluoro-2-methylbutan-3-one and a carrier gas as a medium for electrical insulation and/or for electric arc extinction in medium-voltage

A medium-voltage electrical device, comprising a sealed enclosure comprising electrical components and a mixture comprising a fluoroketone and a carrier gas for electrical insulation and/or extinction of the electric arcs which are produced within this device, wherein:

• the fluoroketone is decafluoro-2-methylbutan-3-one and is present in the mixture in a molar percentage at least equal to 95% of a molar percentage M determined by the formula (I):
• M=(PC5K/Pmixture)×100 (I);
• Pmixture represents a pressure, expressed in kilopascals, of the mixture at 20° C. in the electrical device;
• PC5K represents a pressure, expressed in kilopascals, which is equivalent at 20° C. to a saturation vapor pressure of the decafluoro-2-methylbutan-3-one at a minimum service temperature of the electrical device, where PC5K is determined by formula (II):
• PC5K=(PVSC5K×293)/Tminimum (II);
• PVSC5K represents the saturation vapor pressure of the decafluoro-2-methylbutan-3-one at the minimum service temperature of the electrical device, expressed in kilopascals;
• and
• Tminimum represents the minimum service temperature of the electrical device, expressed in Kelvin.