Patent ID: 7253630

Claim:
A vacuum circuit interrupter comprising: a first terminal; a second terminal; a vacuum switch comprising a vacuum envelope containing a fixed contact assembly and a moveable contact assembly moveable between a closed circuit position in electrical communication with the fixed contact assembly and an open circuit position spaced apart from the fixed contact assembly, said fixed contact assembly being electrically interconnected with said first terminal, said vacuum envelope including a shield; means for electrically connecting said moveable contact assembly to said second terminal; an operating mechanism structured to move said moveable contact assembly between the closed circuit position and the open circuit position, said operating mechanism indicating whether the fixed contact assembly and the moveable contact assembly are intended to be in the open circuit position or the closed circuit position; an electro-optical voltage sensor structured to determine a voltage difference between: said first and second terminals; or said shield and one of said first and second terminals; and a circuit structured to determine no leakage or loss of vacuum of said vacuum envelope when said vacuum switch is intended to be in said open circuit position and when said voltage difference from said electro-optical voltage sensor is greater than a predetermined amount.