Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-09-22
2002-03-19
Dawson, Robert (Department: 1712)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C138S140000
Reexamination Certificate
active
06359038
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to arc-quenching fuse tubes. More particularly, the present invention relates to arc-quenching fuse tubes which are based on synthetic resins.
BACKGROUND OF THE INVENTION
Arc-quenching fuse tubes are well-known in the art and are typically used with electrical cutouts or similar equipment to suppress and/or quench electrical arcing. Arcing can occur when fuse link melting is induced by a fault during operation of an electrical system. To restore normal operation of the system, it is desirable to suppress the arc and clear the fault. Fuse tubes may serve this purpose, and are preferably capable of suppressing and removing arcing conditions repeatedly.
Fuse tubes, and especially the inner surfaces of fuse tubes, are typically formulated from horn fiber, also referred to as bone fiber. Horn fiber is a naturally-occurring substance and is composed largely of keratinous material, which is a tough, fibrous protein. Upon exposure to an electrical arc, horn fiber can decompose, typically via ablation or vaporization. This decomposition generally results in the rapid generation and evolution of gases which interrupt and quench the electrical arc. Horn fiber also possesses desirable mechanical strength and is generally capable of withstanding the high temperature and pressure conditions that can be created by electrical arcs.
Despite the various benefits of horn fiber, including those described above, there are many undesirable drawbacks associated with horn fiber. In this connection, the supply of horn fiber is generally very limited, and its continued availability is uncertain. The manufacture of horn fiber and products which contain horn fiber, such as fuse tubes, is difficult and time-consuming. This tends to increase the cost of horn fiber and horn fiber products.
Generally, fuse tubes contain a liner formulated from horn fiber with a surrounding layer or shell of a synthetic polymeric resin and/or glass fiber. Difficulty has been encountered in achieving a satisfactory bond between the horn fiber liner and this outer layer. In most cases, only a weak mechanical bond can be achieved. Horn fiber is undesirable for this reason also.
Due to the various drawbacks associated with horn fiber, including those discussed above, attempts have been made to develop fuse tubes from materials other than horn fiber. For example, Mattuck et al., U.S. Pat. No. 4,373,555 and Bergh, U.S. Pat. No. 4,373,556, generally disclose cutout fuse tubes which comprise a core or lining of an epoxy resin reinforced with at least about 45% by weight of a polyester fiber. Aluminum trihydrate is incorporated in the Mattuck et al. fuse tubes in an amount of no more than 15% by weight. Although described as a flame retardant, aluminum trihydrate would have very limited flame suppression characteristics at the concentrations disclosed, and would contribute very little, if any, to arc extinguishment.
Fuse tubes in which higher amounts of aluminum trihydrate are incorporated in a synthetic resinous core are disclosed in Rinehart, U.S. Pat. No. 5,015,514. The Rinehart patent teaches the incorporation in the inner core of from about 40% to about 80% by weight of aluminum trihydrate. Such high amounts of aluminum trihydrate can create significant processing difficulties during manufacture of the fuse tubes including, for example, significantly increased viscosities of the resinous compositions. This high viscosity creates handling problems and mixing difficulties, and increased processing times.
Difficulty has also generally been encountered in the manufacture of fuse tubes from synthetic resins, irrespective of the presence of aluminum trihydrate. In this connection, fuse tubes manufactured from synthetic resins are typically manufactured by drawing a fiber, for example, a polyester fiber, through a resin formulation. The resin-coated fiber is then wound, for example, around a mandrel. It is generally desirable to minimize the formation of gaps between adjacent turns of the coated fiber on the mandrel inasmuch as gaps can deleteriously affect the arc-quenching properties of fuse tubes, and ultimately lead to their failure. Methods for preparing fuse tubes from synthetic resins and fibrous materials in which gaps are substantially prevented have generally been unavailable heretofore.
Accordingly, new and/or better fuse tubes and methods for their preparation are needed. The present invention is directed to these, as well as other important ends.
SUMMARY OF THE INVENTION
The present invention is directed, in part, to arc-quenching fuse tubes. Specifically, in one embodiment, there is provided an arc-quenching fuse tube which comprises an elongated tubular body having an inner arc-quenching surface layer. The inner arc-quenching surface layer comprises an arc-quenching matrix comprising a fibrous material and an arc-quenching composition. The arc-quenching composition comprises a cured composition of an aromatic epoxy resin and a linear aliphatic epoxy resin.
Another embodiment of the invention also relates to an arc-quenching fuse tube. The fuse tube is prepared by a process comprising providing a coated fibrous material which comprises a fibrous material substantially coated with a composition comprising an aromatic epoxy resin and an aliphatic epoxy resin. The coated fibrous material is wound around a support member at a winding angle which substantially prevents the formation of gaps.
Yet another embodiment of the invention relates to an arc-quenching fuse tube. The fuse tube is prepared by a process comprising providing a core which is prepared by a process that comprises winding around a support member at a first angle a coated fibrous material. The process further comprises providing an outer shell substantially completely surrounding the core. The outer shell is prepared by a process that comprises winding around the core at a second angle the coated fibrous material.
Still another embodiment of the invention relates to an arc-quenching matrix. The matrix comprises a fibrous material and an arc-quenching composition comprising a cured composition of an aromatic epoxy resin and a linear aliphatic epoxy resin.
Yet another embodiment of the invention relates to a curable fibrous composition comprising a fibrous material and a composition which comprises an aromatic epoxy resin and a linear aliphatic epoxy resin.
Another embodiment of the invention relates to a curable composition comprising an aromatic epoxy resin, a linear aliphatic epoxy resin and an inorganic filler.
Still another embodiment of the invention relates to a process for the preparation of an arc-quenching fuse tube. The process comprises providing a coated fibrous material which is wound around a support member at a winding angle which substantially prevents the formation of gaps between adjacent fiber turns.
Another embodiment of the invention relates to a process for quenching in an electrical system an electrical arc. The process comprises including in the system an arc-quenching fuse tube. At least the inner surface layer of the tube comprises an arc-quenching matrix comprising a fibrous material and an arc-quenching composition. The arc-quenching composition comprises a cured composition of an aromatic epoxy resin and a linear aliphatic epoxy resin.
Yet another embodiment of the invention relates to a process of using in at least an inner surface layer of a fuse tube to quench electrical arcing an arc-quenching matrix. The matrix comprises a fibrous material and an arc-quenching composition comprising a cured composition of an aromatic epoxy resin and a linear aliphatic epoxy resin.
These and other aspects of the invention will become more apparent from the present description and claims.
DETAILED DESCRIPTION OF THE INVENTION
The present invention is directed, in part, to fuse tubes for use in electrical systems. The fuse tubes are desirably capable of quenching arcs which may occur in the electrical systems. The term “quenching”, as used herein, generally refers to the suppression, extinguishmen
Brown Frederick J.
Harvey Ian J.
Loosemore Allan G.
Sievers Brent A.
ABB Power T&D Company Inc.
Aylward D.
Dawson Robert
Woodcock & Washburn LLP
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