Transistor circuit interrupting device

Claim 1

A TRANSISTORIZED STATIC CIRCUIT INTERRUPTING DEVICE FOR INTERRUPTING THE CURRENT SUPPLIED TO A LOAD WHENEVER IT REMAINS ABOVE A PRESCRIBED OVERCURRENT LEVEL FOR LONGER THAN A PRESCRIBED DELAY INTERVAL, COMPRISING: A LOAD CURRENT SUPPLY CIRCUIT FOR CONNECTING SAID LOAD TO A DIRECT CURRENT INPUT SOURCE; CURRENT SENSING MEANS IN SAID CURRENT SUPPLY CIRCUIT FOR PRODUCING A SENSING VOLTAGE PROPORTIONAL TO THE LOAD CURRENT; A TRANSISTOR OVERCURRENT TRIGGER CIRCUIT COUPLED TO SAID CURRENT SENSING MEANS ADAPTED TO PRODUCE A GATING VOLTAGE SO LONG AS THE SENSING VOLTAGE REMAINS AT A LEVEL EXCEEDING THAT CORRESPONDING TO SAID PRESCRIBED OVERCURRENT LEVEL; A PULSE FORMING CIRCUIT CONNECTED TO SAID TRIGGER CIRCUIT FOR DERIVING A GATING PULSE FROM SAID GATING VOLTAGE BY TRANSLATING THE PORTION OF THAT VOLTAGE OCCURRING WITHIN SAID PRESCRIBED DELAY INTERVAL; A TRANSISTOR GATING CIRCUIT CONNECTED TO SAID TRIGGER CIRCUIT AND TO SAID PULSE FORMING CIRCUIT TO RECEIVE BOTH SAID GATING VOLTAGE AND SAID GATING PULSE, SAID GATING CIRCUIT BEING CONSTRUCTED SO THE GATING PULSE HOLDS IT UNRESPONSIVE TO THE GATING VOLTAGE AND SO THAT ON EXPIRATION OF THE GATING PULSE IT PRODUCES A TRIGGER PULSE IN RESPONSE TO A GATING VOLTAGE WHICH CONTINUES BEYOND SUCH EXPIRATION; A TRANSISTOR SIGNAL GENERATING CIRCUIT CONNECTED TO SAID GATING CIRCUIT AND ADAPTED TO RESPOND TO SAID TRIGGER PULSE TO GENERATE AN OVERCURRENT SWITCHING VOLTAGE WHICH CONTINUES FOR A PRESET PERIOD SUBSEQUENT THERETO; AND NORMALLY CONDUCTIVE TRANSISTOR SWITCHING CIRCUIT MEANS IN SAID LOAD CURRENT SUPPLY CIRCUIT AND COUPLED TO SAID SIGNAL GENERATING CIRCUIT MEANS, SAID SWITCHING CIRCUIT MEANS BEING ADAPTED TO BE RENDERED NONCONDUCTIVE BY SAID SWITCHING VOLTAGE SO AS TO OPEN THE LOAD CURRENT CIRCUIT AND MAINTAIN INTERRUPTION OF THE LOAD CURRENT DURING SAID PRESET PERIOD.