Vacuum-type circuit interrupter

Claim 1

IN A VACUUM-TYPE CIRCUIT INTERRUPTER, AN ENVELOPE EVACUATED TO AT LEAST ABOUT 10-4 MM. OF MERCURY, A PAIR OF SEPARABLE ELECTRODES DISPOSED WITHIN SAID ENVELOPE, ONE OF SAID ELECTRODES COMPRISING JUXTAPOSED FIRST AND SECOND ELECTRODE REGIONS FORMED OF DISSIMILAR CONDUCTIVE MATERIALS, THE MATERIAL OF SAID FIRST REGION HAVING A SUBSTANTIALLY LOWER MAXIMUM REPRESENTATIVE CURRENT-CHOPPING LEVEL THAN THE MATERIAL OF SAID SECOND REGION, ARC-INITIATING MEANS FOR INITIATING SUBSTANTIALLY ALL CIRCUIT-INTERRUPTING ARCS WITHIN SAID ENVELOPE IN A LOCATION WHEREIN ONE ARC TERMINAL IS LOCATED ON SAID FIRST ELECTRODE REGION AT THE INSTANT OF ARC-INITIATION, SAID ARC-INITIATING MEANS COMPRISING MEANS FOR CAUSING FINAL PARTING OF SAID ELECTRODES DURING AN INTERRUPTING OPERATION TO OCCUR ON SAID FIRST ELECTRODE REGION, MAGNETIC MEANS FOR DRIVING ARCS FROM THE LOCATION WHERE SAID ARCS ARE INITIATED ONTO SAID SECOND ELECTRODE REGION, MEANS FOR MAINTAINING THE TERMINAL OF LOW CURRENT ARCS ON SAID FIRST ELECTRODE REGION UNTIL ARCEXTINCTION COMPRISING A SURFACE AREA OF SAID FIRST ELECTRODE REGION INTERPOSED BETWEEN ALL ARC-INITIATING LOCATIONS AND SAID SECOND ELECTRODE REGION, SAID MAGNETIC MEANS DRIVING HIGH CURRENT ARCS FROM SAID FIRST ELECTRODE REGION ONTO SAID SECOND ELECTRODE REGION AT A SPEED SUFFICIENTLY HIGH TO LOCATED THE ARC TERMINAL OF SAID HIGH CURRENT ARCS ON SAID SECOND REGION DURING A MAJOR PORTION OF THE ARCING INTERVAL, SAID MAGNETIC MEANS HAVING INSUFFICIENT ARCMOTIVATING ABILITY DURING LOW CURRENT INTERRUPTIONS TO DRIVE THE TERMINAL OF LOW CURRENT ARCS OFF OF SAID FIRST ELECTRODE REGION BEFORE ARC-EXTINCTION.