Vacuum type circuit interrupter with a contact having integral axial magnetic field means

Claim 1

A vacuum type circuit interrupter which includes a housing which is sealingly evacuated, with a pair of relatively movable contacts sealingly supported within the housing, which contacts are movable between a closed position in conductive engagement, and an open position spaced apart to form an arcing gap therebetween across which an arc forms during circuit interruption, the improvement wherein the contacts comprise a conductive base portion connected to a conductive support rod which sealingly extends through the housing, which base portion includes a cup-shaped side wall portion extending toward the opposed contact with a radially inwardly directed annular lip portion at the extending end of the cup-shaped side wall portion, with angled slots formed in the cup-shaped side walls and the annular lip portion to provide an arc rotating force for moving the arc around the annular lip portion, and wherein an annular solid contact rim is provided over the slotted lip portion to serve as the initial arcing surface when the contacts are separated, and wherein a disc-like contact portion is supported within the chamber defined by the cup-shaped side walls and lip of the base portion, by support means extending between the back of the disc-like contact portion and the base, with axial magnetic field producing means disposed within the chamber between the back side of the disc-like contact portion and the base, wherein the axial magnetic field producing means comprises a pair of half-turn conductive coil pieces which are each connected at one end to the back perimeter portion of the disc-like contact portion and at the other end to the base, with the coil pieces spaced between the disc-like contact portion and the base, with the coil piece connections arranged such as to provide a common circular current flow direction as to each contact to provide an additive axial magnetic field.