Protector for dynamoelectric machines

Claim 1

IN A DYNAMOELECTRIC MACHINE HAVING A CURRENT CARRYING WINDING, A PROTECTIVE SYSTEM FOR PREVENTING OVERTEMPERATURE OF SAID WINDING COMPRISING A PLURALITY OF TEMPERATURE SENSITIVE RESISTANCE ELEMENTS CONNECTED IN SERIES EMBEDDED IN SAID WINDING IN CLOSE THERMAL RELATION THERETO, SAID ELEMENTS HAVING A POSITIVE TEMPERATURE COEFFICIENT OF RESISTANCE, A PROTECTIVE RELAY, SAID PROTECTIVE RELAY HAVING AN OPERATING COIL IN SERIES WITH SAID RESISTANCE ELEMENTS AND A SOURCE OF LOW VOLTAGE SUPPLY, NORMALLY OPEN CONTACTS FOR SAID PROTECTIVE RELAY, A MAIN CONTACTOR OPERATING COIL IN SERIES WITH A VOLTAGE SUPPLY AND SAID PROTECTIVE RELAY CONTACTS, SAID TEMPERATURE SENSITIVE RESISTANCE ELEMENTS EACH BEING OF SUCH VALUE AS TO PERMIT THE FLOW OF ENERGIZING CURRENT AT NORMAL OPERATING TEMPERATURES AND TO BLOCK THE FLOW OF ENERGIZING CURRENT AT A PREDETERMINED HIGHER TEMPERATURE WHEREBY A RISE IN THE TEMPERATURE OF SAID WINDING TO SAID PREDETERMINED HIGHER TEMPERATURE IS EFFECTIVE TO DEENERGIZE SAID PROTECTIVE RELAY OPERATING COIL AND DROP OUT SAID PROTECTIVE RELAY CONTACTS THEREBY DEENERGIZING SAID MAIN CONTACTOR OPERATING COIL TO OPEN SAID MAIN CONTACTOR.