Abstract: A time-lag fuse of the type including a fusible element proper, and heat dams formed by strips of sheet metal folded in a direction transversely to the direction of the fusible element proper impeding the axially outer heat flow from said fusible element proper. The fusible element proper has several straight edges extending parallel to the axis of the casing of the fuse. Points of the heat dams engage the inner surface of the casing of the fuse and thus ensure correct positioning of the fusible element proper, i.e. in such a way that its edges extend always parallel to, and are equidistantly spaced from, the axis of the casing. The heat dams engage the inner surface of the casing at discrete points only, to minimize the area of engagement between said heat dams and the inner surface of the casing and to thus minimize direct heat flow from one to the other.
January 27, 1978
Date of Patent:
August 28, 1979
Richard A. Belcher, Frederick J. Kozacka
Abstract: A one piece fusible conductor wherein a current carrying isthmus member in the form of a bridge connects first and second members. The first member has a hole in the vicinity of the isthmus and the hole is filled with a rivet shaped solder deposit and defines current carrying regions of the first member leading to the isthmus. In accordance with the invention, the horizontal profile E of the cross section of each of the latter regions is within a range of 0.7 to 1.00mm and the horizontal profile D of the cross section of the isthmus is within a range from 1.0 to 2.00mm. Furthermore, the profiles E and D satisfy approximately the following relationship: 0.75 .gtoreq. E/D .gtoreq. 0.5.
Abstract: A time-lag fuse constructed so that a fuse element is wound on a core member made of a ceramic material having high thermal conductivity, for example, a material comprising high weight per cent aluminum oxide (Al.sub.2 O.sub.3, 85 - 100 wt.%). The fuse has excellent time-lag characteristics imparted by the strong heat-absorbing action of said high weight per cent aluminum oxide.
Abstract: A time-lag fuse is provided which exhibits improved breaking capacity due to its novel construction. It comprises a fuse element which is securely positioned within an insulating cylindrical tube such as a glass cartridge, and a plurality of sintered ceramic bodies (e.g., cylindrical or polygonal) are circumferentially disposed within said tube so as to define a space therewith to achieve the required fusing and time-lag characteristics. The sintered ceramic bodies are arranged so as to define plurality of spaces between adjacent pairs of the ceramic bodies and the insulating tube in order to buffer the pressure created by arcing between the ceramic bodies and the insulating tube during a current overload.
Abstract: A time-delay fuse is provided comprising a glass or ceramic tube sealed at both ends with a sealing means such as, e.g., ferrules. The fuse also comprises a generally cylindrical core member of poor heat conductivity (e.g., porous sintered mixture of alumina and clay), and a fusible high melting wire element wound densely on the middle region of said core member, thence sparsely toward the terminals and again densely at the ends where the fusible wire element is soldered by a high-melting solder element.
Abstract: A thermal limiter assembly for controlling an electrical circuit in response to the existence of a sensed condition beyond a predetermined time period. A housing body of the assembly includes a gas-filled cavity in which are disposed functional electrical elements in the form of a heater element and a thermally responsive switch or fuselike element. The heater element is arranged to raise the temperature of the thermally responsive element to a critical temperature at which it changes its state of conductivity and is thereby adapted to alter an external circuit connected to it. As disclosed, the heat transfer relationship between the heater element and the thermally responsive element is relatively independent of environmental temperature conditions so that the time period to actuate the thermally responsive element is not substantially affected by such temperature conditions.
Abstract: This invention relates to a self-contained thermal limiter construction which can be used to limit one or more electrical circuits and comprises a thermally responsive device having leads for being interconnected into such electrical circuit or circuits and one or more of electrically operated heaters disposed adjacent the device and each being adapted to cause the device to open the circuit or circuits when heated by the respective heater a certain amount.
Abstract: This invention relates to a thermal limiter which can be used to limit one or more electrical circuits, such as multiple circuits in which one of the circuits is a primary circuit and the other circuits are secondary circuits energized or controlled by the primary circuit. The limiter of this invention is a unitary construction which can be connected to the primary and secondary circuits to control the same. A new method of making the limiter is included in this invention. This invention can be used in combination with a transformer for a television set in combination with its primary and secondary circuits, in combination with an air conditioning system, such as for automobiles, or in combination with other devices, as desired.
Abstract: A layer of material is disposed over at least a portion of a resistive film of a resistor. The material having a melting point lower than the melting point of the resistive film and when melted, chemically reacts with the resistive film to render at least a portion of the film non-conductive.