Ground fault protective means

Claim 1

AN ELECTRICAL SYSTEM FOR PROTECTING OPERATING PERSONNEL AND D.C. POWERED EQUIPMENT HAVING ELECTRICALLY CONDUCTIVE FRAME MEANS FROM THE HARZARDS OF GROUND FAULT ENERGIZATION OF SAID FRAME MEANS AND FOR PREVENTING REVERSE POLARITY ENERGIZATION OF THE EQUIPMENT, COMPRISING A TWO-CONDUCTOR POWER CABLE MEANS CONNECTED TO A D.C. ENERGY SOURCE OVER OVERLOAD CIRCUIT PROTECTIVE MEANS, INPUTAND OUTPUT TERMINAL MEANS ON THE EQUIPMENT EACH CONNECTED WITH ONE OF THE CONDUCTORS OF SAID POWR CABLE, AN OPERATING CIRCUIT CONNECTED TO SAID TERMINAL MEANS AND THE POWERED EQUIPMENT AND HAVING NORMALLY OPEN RELAY OPERATED SWITCH MEAN THEREIN ADAPTED TO BE ACTUATED TO CLOSED POSITION TO ENERGIZE SAID OPERATING CIRCUIT, A CONTROL CIRCUIT CONNECTED TO SAID TERMINAL MEANS IN PARALLEL CIRCUIT RELATIONSHIP WITH SAID OPERATING CIRCUIT AND INCLUDING, IN SERIES, CONTROL SWITCH MEANS, AN OVERLOAD PROTECTIVE DEVICE HAVING NORMALLY CLOSED CIRCUIT-MAKING CONTACTS, A SEMICONDUTOR DEVICE CONDUCTIVE OF ELECTRICAL ENERGY OF A PREDETERMINED POLARITY FOR PREVENTING REVERSE POLARITY ENERGIZATION OF THE CONTROL CIRCUIT, AND OPERATING COIL MEANS OPERABLE UPON ENERGIZATION OF SAID CONTROL CIRCUIT TO CLOSE SAID SWITCH MEANS IN THE SAID OPERATING CIRCUIT; AND A NORMALLY DENERGIZED GROUND FAULT CIRCUIT CONNECTED BETWEEN THE EQUIPMENT FRAME MEANS AND ONE OF SAID POWER CABLE CONDUCTORS FOR TRANSMITTING GROUND FAULT ENERGY UNINTERRUPTEDLY FROM SAID FRAME MEANS TO THE ENERGY SOURCE OVER SAID ONE CONDUCTOR; SAID GROUND FAULT CIRCUIT COMPRISING, IN SERIES, A GROUND FAULT SEMI-CONDUCTOR DEVICE UNIDIRECTIONALLY CONDUCTIVE OF ELECTRICAL ENERGY OF A PREDETERMINED POLARITY AND OPERATING COIL MEANS ADAPTED WHEN ENERGIZED BY PREDETERMINED VALUES OF SAID GROUND FAULT ENERGY TO OPEN THE NORMALLY CLOSED CONTACTS OF SAID OVERLOAD PROTECTIVE DEVICE IN SAID CONTROL CIRCUIT TO DEENERGIZE THE LATTER CIRCUIT AND SAID OPERATING COIL THEREIN THEREBY TO OPEN SAID OPERATING CIRCUIT SWITCH MEANS.