An electric arc-blast nozzle made of a material comprising micro-capsules of liquid (cf3)2cfcn and a circuit breaker including such a nozzle

An electric arc-blast nozzle for a circuit breaker, comprising:

• a middle portion forming a throat defining internally an axial passage for breaking an electric arc, and
• two end portions extending on either side of the middle portion and being designed to receive respective arcing contacts that are movable axially relative to each other, between an open position of the circuit breaker in which the arcing contacts are separated from each other and a closed position of the circuit breaker in which the arcing contacts are in contact with each other and in which one of the arcing contacts partially closes the axial passage of the middle portion, an arc-control gas flowing through the axial passage of the middle portion in order to interrupt an electric arc that is likely to form during movement of the arcing contacts from the closed position to the open position of the circuit breaker,
• the electric arc-blast nozzle being characterized in that the middle portion together with the two end portions are made of a same dielectric material obtained from a composition comprising a fluorocarbon polymer matrix, at least one inorganic filler and micro-capsules of liquid heptafluoro-iso-butyronitrile.

A medium- or high-voltage circuit breaker comprising:

• at least two arcing contacts that are movable axially relative to each other, between an open position of the circuit breaker in which the arcing contacts are separated from each other and a closed position of the circuit breaker in which the arcing contacts are in contact with each other,
• an electric arc-blast nozzle as defined according to claim 1, and
• an arc-control gas flowing through the axial passage of the middle portion of the nozzle in order to interrupt an electric arc that is likely to form during movement of the arcing contacts from the closed position to the open position of the circuit breaker.

A method for releasing heptafluoro-iso-butyronitrile into the arc-control gas of a medium- or high-voltage circuit breaker in use, the arc-control gas comprising heptafluoro-iso-butyronitrile in a mixture with a dilution gas,

• wherein the method consists in implementing a coating formed by a dielectric material obtained from a composition comprising a fluoropolymer matrix, at least one inorganic filler and microcapsules of liquid heptafluoro-iso-butyronitrile inside said medium- or high-voltage circuit breaker.