Arrangement for preventing alternative signalling conditions, especially in road traffic light signalling systems

Claim 1

AN ARRANGEMENT FOR SUPERVISING ALTERNATE SIGNAL CONDITIONS, ESPECIALLY IN ROAD TRAFFIC LIGHT SIGNALLING SYSTEMS COMPRISING: A SOURCE OF POTENTIAL; AT LEAST TWO NETWORKS EACH INCLUDING AT LEAST TWO SIGNAL LAMPS HAVING ONE TERMINAL THEREOF CONNECTED TO ONE TERMINAL OF SAID SOURCE OF POTENTIAL; CONTROL MEANS INCLUDED IN EACH OF SAID NETWORKS TO SELECTIVELY COUPLE THE OTHER TERMINAL OF SAID LAMPS TO THE OTHER TERMINAL OF SAID SOURCE OF POTENTIAL FOR LIGHTING SAID LAMPS; A SUPERVISORY CIRCUIT TO DETERMINE THE OPERATING CONDITION OF SAID LAMPS IN EACH OF SAID NETWORKS INCLUDING AT LEAST ONE RELAY COUPLED BETWEEN SAID CONTROL MEANS OF EACH OF SAID NETWORKS, AND FIRST MEANS INCLUDING MEANS SELECTIVELY OPERABLE BY SAID AT LEAST ONE RELAY IN EACH OF SAID NETWORKS TO COUPLE SAID ONE AND SAID OTHER TERMINAL OF SAID SOURCE OF POTENTIAL; AND TROUBLE INDICATING MEANS COUPLED TO EACH OF SAID CONTROL MEANS, SAID RELAY BEING RESPONSIVE TO THE ACTIVATION OF MORE THAN ONE OF SAID CONTROL MEANS AND THE ENSUING INOPERATIVENESS OF SAID RELAY TO PRODUCE A TROUBLE INDICATING OUTPUT AND THE ACTIVATION OF ONLY ONE OF SAID CONTROL MEANS ENERGIZING SAID RELAY TO PRODUCE A TROUBLE FREE INDICATING OUTPUT.