Impedance protective systems

Claim 1

AN IMPEDANCE PROTECTIVE ARRANGEMENT FOR A CIRCUIT CONNECTED TO A SOURCE OF ALTERNATING CURRENT COMPRISING MEANS FOR PRODUCING A FIRST ALTERNATING VOLTAGE PROPORTIONAL TO THE VOLTAGE IN SAID CIRCUIT, A MUTUAL INDUCTANCE ASSOCIATED WITH SAID CIRCUIT AND HAVING A PRIMARY WINDING CARRYING THE CURRENT IN SAID CIRCUIT, MEANS FOR OBTAINING FROM THE SECONDARY WINDING OF SAID MUTUAL INDUCTANCE A SECOND ALTERNATING VOLTAGE PROPORTIONAL TO THE CURRENT IN SAID CIRCUIT, MEANS FOR OBTAINING FROM THE SECONDARY WINDING OF SAID MUTUAL INDUCTANCE A THIRD ALTERNATING VOLTAGE PROPORTIONAL TO THE RESISTANCE OF SAID CIRCUIT, MEANS FOR OBTAINING THE VECTORIAL DIFFERENCE BETWEEN THE SUM OF SAID SECOND AND THIRD VOLTAGES AND SAID FIRST VOLTAGE, MEANS FOR COMPARING IN CORRESPONDING ALTERNATE HALF-CYCLES SAID FIRST VOLTAGE WITH SAID VECTORIAL DIFFERENCE, A PROTECTIVE DEVICE ADAPTED TO DISCONNECT SAID CIRCUIT FROM SAID SOURCE, AND MEANS FOR ENERGIZING SAID PROTECTIVE DEVICE WHEN, IN SUCCESSIVE HALF-CYCLES, SAID VECTOR DIFFERENCE REVERSES IN PHASE WITH REFERENCE TO SAID FIRST VOLTAGE AS COMPARED WITH ITS PHASE WITH REFERENCE TO SAID FIRST VOLTAGE WHEN SAID CIRCUIT IS HEALTHY.