Patent ID: 8658932

Claim:
A device for detecting vacuum loss in a vacuum breaking apparatus, said apparatus being situated in an electrically supplied primary power system and comprising an enclosure, the enclosure comprising: a first part of substantially cylindrical shape at least partially made from an insulating material such as ceramic, said first part being closed at its two opposite ends by two end-plates, said enclosure housing a fixed electrode securely attached to one of the above-mentioned end-plates and supporting a stationary contact, and a mobile electrode supporting a movable contact, said mobile electrode being mounted in sliding manner through the other of the two end-plates between a closed position of the apparatus in which the movable contact is in contact with the stationary contact and an open position of the apparatus in which the movable contact is separated from the stationary contact; a second part made from insulating material and placed at least partially around the first part, this second part comprising a layer of electrically earthed conducting material forming a shielding on at least a part of its outer surface, a first strip of conducting material is insulated from the rest of said layer, the first strip being located facing both the first insulating part and either the fixed or mobile electrode, the first strip forming a capacitance composed of a first and a second capacitances in series; wherein the first capacitance is a vacuum capacitance located between the mobile or fixed electrode and the inner surface of the first part; and wherein the second capacitance is a solid capacitance fitted between the inner surface of the first part and the first strip; and means for measuring the current flowing in the first strip connected to indicating means, a certain change in the value of the current value translating a change of value of the vacuum capacitance, which change translates a vacuum loss inside the vacuum breaking apparatus.