Apparatus and method for measuring the pressure inside a vacuum circuit interrupter

Claim 1

IN AN ARRANGEMENT FOR MEASURING THE PRESSURE INSIDE A VACUUM CIRCUIT INTERRUPTER OF THE TYPE COMPRISING AN EVACUATED ENVELOPE, A TUBULAR VAPOR-CONDENSING SHIELD LOCATED INSIDE THE ENVELOPE ADJACENT THE INNER PERIPHERY OF THE ENVELOPE FOR PROTECTING THE ENVELOPE AGAINST VAPOR CONDENSATION, AND INNER STRUCTURE DISPOSED INTERNALLY OF THE TUBULAR SHIELD COMPRISING A PAIR OF ELECTRODE BETWEEN WHICH ARCS ARE ESTABLISHED DURING INTERRUPTER OPERATION, A PORTION OF SAID INNER STRUCTURE NORMALLY BEING ELECTRICALLY ISOLATED FROM THE SHIELD BY AN EVACUATED SPACE ENCLOSED BY SAID SHIELD AND SURROUNDING SAID INNER STRUCTURE PORTION, THE COMBINATION OF: (A) MEANS COMPRISING AN EXTERNAL CIRCUIT HAVING A PAIR OF TERMINALS ADAPTED TO BE ELECTRICALLY CONNECTED TO SAID SHIELD AND SAID INNER STRUCTURE PORTION, RESPECTIVELY, FOR APPLYING A UNIDIRECTIONAL VOLTAGE BETWEEN SAID SHIELD AND SAID INNER STRUCTURE PORTION OF SUCH A POLARITY THAT SAID SHIELD ACTS AS AN ANODE AND SAID INNER STRUCTURE PORTION ACTS AS A CATHODE, (B) MEANS LOCATED EXTERNALLY OF SAID ENVELOPE FOR ESTABLISHING A MAGNETIC FIELD HAVING ITS LINES OF FORCE EXTENDING LONGITUDINALLY OF SAID TUBULAR SHIELD THROUGH THE SPACE ENCLOSED BY SAID SHIELD SURROUNDING SAID INNER STRUCTURE PORTION, (C) AND MEANS FOR MEASURING THE CURRENT IN SAID EXTERNAL CIRCUIT WHEN SAID UNIDIRECTIONAL VOLTAGE IS APPLIED WITH SAID MAGNETIC FIELD PRESENT.