Measuring and testing – Hardness – By penetrator or indentor
Reexamination Certificate
2002-03-28
2003-10-21
Williams, Hezron (Department: 2855)
Measuring and testing
Hardness
By penetrator or indentor
C073S082000
Reexamination Certificate
active
06634217
ABSTRACT:
TECHNICAL FIELD
The invention relates to tools for handling live electrical conductors, and more particularly to a method and tool for testing the hardness of a live electrical conductor.
BACKGROUND ART
Copper wire has been widely used in the past as the material of construction for electrical power distribution lines. Some distribution lines contain soft annealed copper wire, while others contain hard drawn or medium hard drawn copper wire. Hard drawn and medium hard drawn wire have a considerably higher minimum breaking strength than soft annealed wire. When soft annealed copper wire distribution lines are restrung due to aging, there is a risk of breakage and in-service failure.
In order to distinguish which distribution lines are made of hard drawn copper and which are made of soft annealed copper, hardness testing must be done. Since existing methods of hardness testing require that the power through the wire be shut down prior to testing, it has been considered more efficient to simply replace all the copper wire, whether hard, medium hard drawn or soft annealed, with aluminum conductors. This represents a considerable waste of perfectly serviceable wire. If the hard or medium hard drawn wire could be preserved by hardness testing without any power disruption, such blanket replacement programs could be avoided. What is needed is a method and tool for live testing of the hardness of distribution line copper conductors.
DISCLOSURE OF INVENTION
The present invention provides a method of live testing of the hardness of a target electrical distribution wire having a known gauge. The method comprises a) providing a hardness testing tool at the operating end of an insulated tool for manipulating live distribution lines, wherein the hardness testing tool comprises a testing surface of known hardness; b) forcing the testing surface against the target wire; and c)comparing the resultant degree of deformation or lack of deformation on the testing surface with the expected degree of deformation which would occur for wire of that gauge having a specific hardness.
The present invention further provides a tool for live testing of the hardness of a target electrical distribution wire having a known gauge. The tool comprises an elongated insulated handle and is provided at the operating end thereof with a hardness testing element, wherein the hardness testing element comprises a testing surface of known hardness, the hardness testing element being adapted to force the testing surface against the target wire.
REFERENCES:
patent: 4079978 (1978-03-01), McMullin
patent: 4535623 (1985-08-01), Gilberto
patent: 5337566 (1994-08-01), Lomastro et al.
patent: 5341088 (1994-08-01), Davis
patent: 5397982 (1995-03-01), Van Lankvelt
Bhuyan Gouri S.
Kung Chien Kang
O'Hara Roy G.
Rao Avaral S.
Tarampi Dexter G.
British Columbia Hydro and Power Authority
Oyen Wiggs Green & Mutala
Williams Hezron
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