Transformer fuse

Claim 1

IN AN ELECTRICAL DISTRIBUTION TRANSFORMER, IN COMBINATION, A CASING, A TRANSFORMER CORE AND COIL ASSMEBLY WITHIN SAID CASING INCLUDING A MAGNETIC CORE LINKED BY PRIMARY AND SECONDARY WINDINGS, A DIELECTRIC INSULATING LIQUID WITHIN SAID CASING SURROUNDING SAID CORE AND COIL ASSEMBLY, AND A FUSE WITHIN SAID CASING IMMERSED IN SAID LIQUID AND IN SERIES RELATION WITH SAID PRIMARY WINDING, SAID FUSE INCLUDING A RELATIVELY HIGH MELTING TEMPERATURE FUSIBLE WIRE ELEMENT, A RELATIVELY LOW MELTING TEMPERATURE FUSIBLE ELEMENT COMPRISING A MASS OF SOLDER AFFIXED TO SAID FUSIBLE WIRE, A TUBE OF INSULATING MATERIAL ADAPTED TO EVOLVE GAS IN THE PRESENCE OF AN ARC SURROUNDING SAID WIRE AND SAID SOLDER MASS FUSIBLE ELEMENTS, MEANS ENGAGING ONE END OF SAID TUBE AND ONE OF SAID FUSIBLE ELEMENTS FOR PREVENTING MOVEMENT OF SAID ONE FUSIBLE ELEMENT RELATIVE TO SAID TUBE, SPRING MEANS DISPOSED WITHIN SAID TUBE AND ENGAGING THE OTHER END OF SAID TUBE AND THE OTHER ONE OF SAID FUSIBLE ELEMENTS FOR RESILIENTLY BIASING SAID OTHER FUSIBLE ELEMENT TOWARD MOVEMENT WITHIN SAID TUBE INCIDENT TO RUPTURE OF ONE OF SAID FUSIBLE ELEMENTS, SAID FUSIBLE WIRE BEING RUPTURABLE IN RESPONSE TO I2R HEATING BY SHORT CIRCUIT CURRENT THROUGH SAID FUSE GREATER THAN APPROXIMATELY TWENTY TIMES THE NORMAL CURRENT OF SAID PRIMARY WINDING, SAID SOLDER MASS BEING RUPTURABLE IN RESPONS TO I2R HEATING BY CURRENT THROUGH SAID FUSE OF LONGER DURATION THAN SAID SHORT CIRCUIT CURRENT AND OF A MAGNITUDE GREATER THAN APPROXIMATELY EIGHT TIMES SAID PRIMARY WINDING NORMAL CURRENT AND ALSO BEING RUPTURABLE IN RESPONSE TO OVERHEATING OF SAID LIQUID CAUSED BY A CURRENT OF STILL GREATER DURATION AND OF MAGNITUDE LESS THAN APPROXIMATELY EIGHT TIMES SAID PRIMARY WINDING NORMAL CURRENT.