High voltage circuit-interrupters

A high voltage circuit-interrupter for operation within an enclosure containing an insulating fluid medium comprising

• a fixed contact having a bore,
• a fixed support structure having a bore on generally the same axis as the fixed contact and spaced therefrom including a puffer type piston,
• a hollow driving tube axially movable within the bore of the fixed structure and thus axially movable relative to the fixed contact, the driving tube adapted to be driven by external driving means, the driving tube including a stop means within the bore and carrying a puffer type cylinder capable of cooperating with said puffer type piston to create a flow of insulating fluid medium,
• a contact assembly on an end of said driving tube and adjacent to the fixed contact, the contact assembly comprising
• an insulating nozzle adapted to surround said fixed contact, and a generally tubular main electrical contact within the nozzle, said contact assembly having a radial passage extending from exterior of the contact assembly through to the interior of the main electrical contact,
• the interrupter further including
• a tubular auxiliary contact positioned within the main electrical contact and axially movable relative to the main electrical contact and relative to the hollow driving tube by a biased spring carried within the hollow driving tube, the auxiliary contact having a port capable of aligning with said radial passage in said contact assembly, having stop means engagable with the stop means of the driving tube, and having a rooting electrode fixed within the auxiliary contact by a spider, the rooting electrode having a gas deflecting portion closing the hollow driving tube,
• whereby upon initial axial movement of the contact assembly from a position surrounding the fixed contact caused by an external driving means, the auxiliary contact maintains electrical contact with the fixed contact by the action of the biased spring and the movement of the puffer cylinder and piston relative to each other increases the pressure in the fluid medium within the contact assembly around the fixed contact and the main contact and
• whereby upon further movement of the contact assembly away from the fixed contact, the auxiliary contact separates from the fixed contact by means of the stop means of the auxiliary contact engaging the stop means of the driving tube and the port in the auxiliary contact and the radial passage in the contact assembly align so as to allow fluid medium flow driven by said pressure increase inwardly into a gap formed between the separated fixed contact and auxiliary contact and through the bore of said auxiliary contact and be deflected by the gas deflecting portion of the rooting electrode into the radial passage of the contact assembly and thereby provide radial venting of the interrupter through a low-impedance radial venting path external to the puffer piston and cylinder and in close proximity to the contacts.