Vacuum-type circuit interrupters with condensing shield at a fixed potential relative to the contacts

An alternating current circuit interrupter of the vacuum type, including in combination:

• a. a generally cylindrical insulating casing defining a highly-evacuated envelope;
• b. a pair of relatively movable conductive contact posts sealingly extending through opposed ends of the envelope along the longitudinal axis of the cylindrical insulating casing;
• c. arc contact members disposed at the ends of the respective contact posts within the space defined by the cylindrical insulating casing;
• d. a single centrally disposed metallic condensing shield supported from the cylindrical insulating casing and centrally disposed within the space defined by the cylindrical insulating casing about the arc contacts and the gap between the contacts when they are spaced apart to shield the insulating casing from vaporized metal from the contacts;
• e. a resistive coating disposed on the interior or exterior surface of the insulating casing and electrically contacting the centrally disposed metallic condensing shield, which resistive coating extends to and serially electrically connects the condensing shield to at least one of the contact posts whereby the potential on the condensing shield may be quickly dissipated through the resistive coating.