Appeal 2007-3126
Application 10/359,275
Zunick does not disclose placing any type of sensor inside tubular shaft 25,
let alone encasing such a sensor in an elastic compound different from the material
of which the shaft is formed, as required by claim 1. Instead, the only sensor
disclosed by Zunick is a current pick-up 28 that surrounds contact bushing 6 (col.
3, ll. 5-57).
ABDELGAWAD
Figure 5 of Abdelgawad shows a high-voltage vacuum switching device that
includes a vacuum switch 62 (col. 4, l. 35) and a pull-rod 73 that is formed of any
suitable insulating material, such as porcelain or “Polysil” (col. 4, ll. 51-53), which
is identified as a trademark of the Electric Power Research Institute for a casting
material that is a mixture of inorganic fillers such as silica, and an organic resin
such as a polyester or methylmethacrylate (col. 3, ll. 62-65). The Figure 5
embodiment includes two types of sensing circuits, neither of which is contained in
the pull-rod. The first sensing circuit is a transformer 90 that surrounds the upper
electrode 50 for sensing current (col. 5, ll. 27-29). The transformer and upper
electrode are contained in an initial epoxy casting 138 made with a specially
engineered epoxy (col. 8, ll. 11-18). That engineered epoxy, which is also used to
form the second casting 170 (col. 8, ll. 27-31), “has a high dielectric strength, good
corona properties, and thermal coefficient of expansion characteristics to provide a
mechanically sound integrated electrical system” (col. 9, ll. 41-44).
The second sensing circuit is a voltage-sensing circuit, which is provided
because “current sensing alone is not a reliable indicator under circumstances
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