Abstract: An arrangement for releasably securing or connecting together at least two components includes a securing element that interconnects the components and that can be melted, thermally decomposed or otherwise separated by applying heat thereto. The securing element is preferably a monofilament or multifilament thread of natural or synthetic material, such as high strength polymer material. The arrangement further preferably includes a compression bracing structure such as a housing that bears compression forces between the components, while the securing element bears tension forces. The arrangement further preferably includes an electric resistance heating element that can be electrically energized and is arranged to apply heat to the thread, so as to melt or decompose and separate the thread and thereby release and separate the two interconnected components.

Abstract: A normally closed electrical switch mechanism having fixed and movable switch assemblies, a spring assembly urging the movable switch assembly away from engagement with the fixed switch assembly to thereby open the switch, a latch member normally securing the movable switch assembly in its position of engagement with the fixed switch assembly, and a mechanism responsive to a predetermined condition external to the switch mechanism for moving the latch member so as to allow the switch to open, is improved in the following manner. A member made of thermoplastic material is positioned between the latch member and the movable switch assembly. The thermoplastic material of that member is then responsive to an overheated condition of the internal switch circuitry for losing its structural rigidity so as to release the movable switch assembly and thereby permit the spring assembly to open the switch even though the latch member remains in place.

Abstract: A polyphase interrupter includes an electric fuse in series with each phase, a phase grounding conductor electrically connected with each phase and movably mounted adjacent and electrically connected with a terminal of each fuse, biasing means arranged to impart individual grounding movement to each phase grounding conductor, latch means normally in engagement with each phase grounding conductor for preventing grounding movement thereof, actuating means associated with each of said fuses and movable into releasing engagement with the associated latch means in response to current interrupting operation of the associated fuse, and coupling means interconnecting all of said latch means for imparting simultaneous releasing movement thereby to effect grounding and interruption of all phases in response to interruption in one phase.

Abstract: A thermal overload relay for a three-phase power supply circuit having an auxiliary normally open (N.O.) or a normally closed (N.C.) contact unit (FIG. 5, FIG. 6) selectively addable in the field. The relay is provided with the standard normally closed contact by way of a subassembly (20) that is installed by the manufacturer for circuit protective purposes and a slot (12p) and securing means (12n, 77) alongside this subassembly for receiving an auxiliary contact unit (57) that can be inserted and secured by a screw (77) in the field. A contact operating lever (54) is constructed so that it will actuate the auxiliary contact unit (57) at the end of the trip stroke thereby affording redistribution or retiming of the spring forces that will enhance the tripping function because less initial spring force is required at the beginning of the trip stroke. The N.O. and N.C.