Tap changing device for transformer windings without interrupting the load current

Claim 1

IN A TAP CHANGER DEVICE FOR A CONTROLLABLE TRANSFORMER HAVING A WINDING PROVIDED WITH FIRST AND SECOND SETS OF TAP POINTS, FIRST AND SECOND TAP CHANGING SWITCHING MEANS FOR CONNECTING SELECTED TAPPING POINTS OF SAID FIRST AND SECOND SETS RESPECTIVELY TO FIRST AND SECOND LEAD OFF CONDUCTORS, A PAIR OF DIVERTER SWITCHES, EACH SAID DIVERTER SWITCH INCLUDING A FIRST CONTACT MEMBER MOVABLE INTO SELECTIVE ENGAGEMENT WITH A SECOND OR THIRD CONTACT MEMBER, CIRCUIT MEANS CONNECTING SAID SECOND CONTACT MEMBERS OF SAID DIVERTER SWITCHES WITH SAID FIRST LEAD OFF CONDUCTOR, CIRCUIT MEANS CONNECTING SAID THIRD CONTACT MEMBERS OF SAID DIVERTER SWITCHES WITH SAID SECOND LEAD OFF CONDUCTOR, AN OUTPUT LEAD CONNECTED TO A FIRST CONTACT MEMBER OF ONE OF SAID DIVERTER SWITCHES, A PLURALITY OF CIRCUIT BREAKERS CONNECTED IN SERIES BETWEEN SAID FIRST CONTACT MEMBERS OF SAID DIVERTER SWITCHES, MEANS BIASING THE CONTACTS OF SAID CIRCUIT BREAKERS TO A CLOSED POSITION, SAID CIRCUIT BREAKER CONTACTS REMAINING CLOSED WHEN TRAVERSED BY NORMAL LOAD CURRENTS TAKEN OFF SAID TAPPED TRANSFORMER WINDING BUT OPENING AUTOMATICALLY BY ELECTRODYNAMIC EFFECT OF THE CURRENT CARRIED THEREBY WHEN SAID CURRENT RISES ABOVE THE NORMAL LOAD LEVEL AS A RESULT OF A SHORT CIRCUIT ESTABLISHED THROUGH A PORTION OF SAID TRANSFORMER WINDING BETWEEN TAPS THEREON WHEN SAID DIVERTER SWITCHES ARE ACTUATED, AND TIME DELAY MEANS OPPOSING THE ACTION OF SAID BIASING MEANS OF SAID CIRCUIT BREAKERS IN RE-CLOSING THE CONTACTS THEREOF.