Protective circuit using silicon controlled rectifier

Claim 1

A CIRCUIT FOR PREVENTING CURRENT THROUGH A LOAD CIRCUIT COMPRISING A NON-CONDUCTING SILICON CONTROLLED RECTIFIER CONNECTED ACROSS SAID LOAD CIRCUIT, SAID SILICON CONTROLLED RECTIFIER INCLUDING A GATING ELECTRODE FOR SWITCHING SAID RECTIFIER TO A CONDUCTING STATE UPON THE APPLICATION OF A SIGNAL THERETO, A SOURCE OF INPUT VOLTAGE TO BE APPLIED TO SAID LOAD, A STORAGE CIRCUIT FOR STORING VOLTAGE OF SUBSTANTIALLY THE SAME AMPLITUDE AS SAID INPUT VOLTAGE, NORMALLY OPEN, SWITCHING CONTACTS CONNECTED BETWEEN SAID SILICON CONTROLLED RECTIFIER AND SAID SOURCE OF VOLTAGE, A VOLTAGE SENSITIVE RELAY FOR CLOSING SAID SWITCHING CONTACTS WHEN CURRENT FLOWS THROUGH SAID RELAY, SAID RELAY BEING CONNECTED BETWEEN SAID STORAGE CIRCUIT AND SAID SOURCE OF INPUT VOLTAGE, WHEREBY CURRENT FLOWS THROUGH SAID RELAY WHEN THE AMPLITUDE OF SAID INPUTS VOLTAGE DROPS BELOW THE AMPLITUDE OF THE VOLTAGE AT SAID STORAGE MEANS TO CAUSE A SIGNAL FROM SAID SOURCE OF VOLTAGE TO BE APPLIED TO THE GATING ELECTRODE OF SAID SILICON CONTROLLED RECTIFIER, SAID SILICON CONTROLLED RECTIFIER BEING DRIVEN TO A CONDUCTING STATE TO PRODUCE A RELATIVELY LOW IMPEDENCE PATH ACROSS SAID LOAD, AND ADDITIONAL MEANS FOR DETECTING A DROP IN THE VOLTAGE OF SAID INPUT VOLTAGE TO DISCONNECT SAID SOURCE OF VOLTAGE FROM SAID LOAD CIRCUIT.