Electricity: conductors and insulators – Conduits – cables or conductors – Insulated
Reexamination Certificate
1999-04-01
2001-03-27
Nguyen, Khiem (Department: 2839)
Electricity: conductors and insulators
Conduits, cables or conductors
Insulated
C439S488000, C174S015700
Reexamination Certificate
active
06207902
ABSTRACT:
This invention relates to an electrical wiring cable and has specific relevance to electrical wiring cable used in high wear, high abrasion applications.
BACKGROUND OF THE INVENTION
The construction of electrical wiring cable is well settled in the electrical and electronic arts. A wide variety of conductive and insulating materials have been used in a multitude of different configurations. The type of electrical wiring cable employed in any particular application is determined by the electrical and physical requirements and parameters of that particular application. Some wiring cable applications require greater shielding and insulation, while others require protecting the conductors and insulation from physical or chemical damage.
One common construction for electrical wiring cable comprises a number of electrical conductors composed of a single conductive wire or multiple stranded wires, an extruded insulator of nonconductive material enclosing the conductors, and an outer jacket or sheathing, which protects the conductors and extruded insulator from various physical and chemical damage. This type of electrical wiring cable has a wide range of electrical applications, including high voltage and high current power cable applications.
In many electrical applications, wiring is laid in a static environment, that is, once laid in its environment, the cable is exposed to limited movement (bending) and external contact. In a static environment, the physical damage that wiring cable was typically exposed to was severing or cuts in the jackets, sheathing and/or insulators caused by the cable being laid on or over sharp objects or caused by other similar types of damage in a static environment. Consequently, the physical requirement on the wiring cable with regard to durability and abrasion resistance generally has been of limited concern in conventional wiring cable construction.
However, durability and abrasion resistance has become an increasing concern for wiring cable construction used in dynamic applications, such as automated and robotic assembly systems. For example wiring cables used in articular robotic arms are subject to wear abrasions and damage caused by the wiring cables being physically rubbed against the articulated component of the robotic and other foreign objects, as well as being repeatedly bent and pulled as the arm moves. The new dynamic application of conventional wiring cable has placed increased importance on its flexibility, durability and abrasion resistance. Although improvements in the construction of wiring cables have been developed for these high wear, high abrasion applications, the problem of wear abrasions has not been fully addressed, since physical wear on wiring cable is inevitable in any dynamic application. Wear abrasions can occur on conventional wiring cables without notice. Heretofore, wear abrasions on wiring cables are not visibly detectable due to the coloration of the cable's outer jacket and insulators employed by conventional wiring cable constructions. Without visual indication or physical inspection, the wear and damage to the cable may go unnoticed, which eventually leads to electrical hazards and failure.
SUMMARY OF THE INVENTION
The improvement of this invention to the construction of conventional electrical wiring cable provides a visible indication of wear abrasion before an electrical hazard is created in high wear, high abrasion cable applications. The improvement to conventional wiring cable construction is the use of contrasting colors between the extruded insulator and the outer jacket materials in the cable. When the outer jacket of the cable is worn down, cut or damaged, the underlying insulator of a contrasting color becomes visible against the outer jacket thereby indicating a hazard condition.
Although a variety of conventional wiring cables have used jacketing, shielding and insulation materials with various color combinations, heretofore, the advantage of using a colored jacket and extruded insulators with contrasting colors to provide a means for visually indicating wear and damage to a cable's protective outer jacket and insulation in high wear, high abrasion application has been under appreciated. For example, automated resistance welding systems used in the automobile industry use conventional power cables mounted to articulated robot arms, and those cables have a single extruded insulator over three stranded conductors that are individually insulated by only a thin inner jacket (See FIG.
1
). Due to the uniform color of the single extruded insulator, an abrasion can be worn down to the thin inner jacket before it is visibly noticed or discovered by routine inspection. The use of wiring cable with jacketing and insulators of contrasting color would eliminate this problem.
Accordingly, an advantage of this invention is that the use of electrical wiring cable with color contrasted jacketing and insulators provides a visual indication of wear abrasion before a hazard condition occurs.
Another advantage of this invention is that conventional wiring cable construction can be used for an unappreciated result by the use of contrasting colors between the outer jacketing and the inner extruded insulation.
Another advantage of this invention is that the use of the wiring cable with color contrasted jacketing and insulators easily allows electrical wiring cable to be visually monitored for replacement without close or timely inspection.
Other advantages will become apparent upon a reading of the following description.
REFERENCES:
patent: 3505916 (1970-04-01), Brandt
patent: 4423306 (1983-12-01), Fox
patent: 4808966 (1989-02-01), Ferlier et al.
patent: 5228478 (1993-07-01), Kleisle
patent: 5719353 (1998-02-01), Carlson et al.
Crump R. Tracy
Nguyen Khiem
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