Contact assembly for high-voltage switch

A contact assembly is provided for a high-voltage switch. The contact assembly includes one or more contact members that cooperate with a contact element. The arrangement of the contact members is such that an interference fit results with the contact element and one or more of the contact members are displaced. To provide operation of the contact assembly in ice-forming environments, facilities are provided to prevent the ingress of moisture and the formation of ice in the space required for displacement of the appropriate one or more contact members. Of course, if ice were allowed to occupy the space required for displacement of the one or more contact members, due to the relatively incompressible nature of ice, appropriate contact engagement would be inhibited since displacement of the one or more contact members would be unable to occur when engaged by the contact element. In a specific arrangement, the contact assembly includes a contact support structure which carries the contact members. A filler element is provided between the contact support structure and the contact members that are required to be displaceable. The filler element is deformable and/or compressible in response to the displacement of the contact member. Additionally, the filler element is impervious to the ingress of moisture or the formation of ice crystals and retains its flexiblity under ice-forming conditions.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates generally to structures having movable 
members which operate under ice-forming conditions, and more particularly 
to a contact assembly for a high-voltage switch. 
2. Description of Related Art 
Various arrangements are provided for high-voltage switches to prevent ice 
from forming on critical portions of contact structures; e.g., to avoid 
the accumulation of ice that might inhibit or prevent suitable cooperation 
of contacts. 
A first type of ice-excluding design utilizes plate-like shields or hoods 
which are generally rigid and enclose or shield the contact assembly. The 
shield is arranged so as not to interfere with the operation of a movable 
contact with a contact assembly. 
Another type of ice-excluding arrangement provides flexible shields which 
move out of the way when acted upon by the movable contact. For example, 
U.S. Pat. No. 4,296,284 discloses such an arrangement. 
While these arrangements may be generally suitable for their intended 
purposes, neither of these two basic approaches prevents the ingress of 
moisture to critical portions of the contact structure. Additionally, the 
fixed shields are rather cumbersome and expensive and, under some 
environmental conditions, are not even totally effective in preventing 
precipitation from directly entering the contact structures. The flexible 
shields are also not totally effective under all circumstances and, 
additionally, complicate the operation of the switch; either by requiring 
appropriate mechanisms for moving the flexible shield out of the way 
during operation or by requiring that the moving contact engage the 
flexible shield. Further, the shields themselves are also subject to being 
bound up by ice or corrosion. 
SUMMARY OF THE INVENTION 
Accordingly, it is a principal object of the present invention to provide a 
contact assembly for a high-voltage switch which allows operation of the 
switching device in ice-forming environments without the use of either 
fixed or movable shields. 
It is another object of the present invention to provide a contact assembly 
for a high-voltage switch of the type which utilizes one or more contact 
members that cooperate with a contact element; the contact assembly 
including provisions such that the displacement of one or more of the 
contact members in ice-forming environments is not inhibited or 
restricted. 
Briefly, these and other objects of the present invention are efficiently 
achieved by the provision of a contact assembly for a high-voltage switch. 
The contact assembly includes one or more contact members that cooperate 
with a contact element. The arrangement of the contact members is such 
that an interference fit results with the contact element and one or more 
of the contact members are displaced. To provide operation of the contact 
assembly in ice-forming environments, facilities are provided to prevent 
the ingress of moisture and the formation of ice in the space required for 
displacement of the appropriate one or more contact members. Of course, if 
ice were allowed to occupy the space required for displacement of the one 
or more contact members, due to the relatively incompressible nature of 
ice, appropriate contact engagement would be inhibited since displacement 
of the one or more contact members would be unable to occur when engaged 
by the contact element. In a specific arrangement, the contact assembly 
includes a contact support structure which carries the contact members. A 
filler element is provided between the contact support structure and the 
contact members that are required to be displaceable. The filler element 
is deformable and/or compressible in response to the displacement of the 
contact member. Additionally, the filler element is impervious to the 
ingress of moisture or the formation of ice crystals and retains its 
flexibility under ice-forming conditions.

DETAILED DESCRIPTION 
Referring now to FIGS. 1 and 2, the contact assembly 10 of the present 
invention is illustrated in conjunction with a movable contact arm 12, 
which is illustrated in a partially closed position. The movable contact 
arm 12 is also referred to as a disconnect blade in a high-voltage switch 
configuration. The movable contact arm 12 includess a movable contact 
element 14 which is arranged to cooperate with the contact members 16, 18, 
and 20 and a fourth contact member 22, not shown but located behind the 
contact member 20 in FIG. 1. The contact members 16, 18, 20, and 22 are 
resiliently mounted by springs 24,26 with respect to a contact support 
structure 28. A spacer element 30 is positioned between each of the 
springs 24,26 and the respective contact member. The contact members 16, 
18, 20, and 22 are arranged in a pattern so as to define a gap of 
predetermined dimension 52 such that the contact members are displaced by 
the movable contact element 14 as it moves from the position shown in 
solid in FIGS. 1 and 2 to the fully closed position 12' shown in phantom 
in FIGS. 1 and 2; i.e., as the movable contact arm 12 and the movable 
contact element 14 are vertically lowered and slightly rotated. In 
response to the interference fit of the movable contact element 14 and the 
spaced contact members 16, 18, 20, and 22, the contact members 16, 18, 20, 
and 22 are displaced and a contact force or pressure results between the 
movable contact element 14 and the contact members 16, 18, 20, and 22. 
The contact members 16, 18, 20, and 22 are generally U-shaped and include a 
first leg 32 that functions as a contact finger. The second leg 34 of the 
contact member is attached to the contact support 28 via fastener 36. The 
fastener 36 extends through both legs 32,34 of the contact members 16, 18, 
20, and 22 and the contact support 28 via respective holes 33, 35, and 29. 
In accordance with important aspects of the present invention, a filler 
element 40 is provided between the first leg 32 of each of the contact 
members 16, 18, 20, and 22 and the inner face 31 of the contact support 
28. The filler element 40 provides a moisture and ice-excluding function 
by preventing the formation of ice in the area required for the 
displacement of the first leg 32 of each of the contact members 16, 18, 
20, and 22. For example, without the provision of the filler element 40, 
various shields are required in an attempt to prevent moisture and ice 
from entering the space between the contact members 16, 18, 20, and 22 and 
the contact support structure 28; i.e., the volume through which the 
contact members 16, 18, 20, and 22 are displaced when the contact element 
14 is moved to the fully closed position 14'. However, in addition to such 
shields not being fully effective, the provision of the filler element 40 
renders such shields unnecessary. The filler elements 40 are deformable 
and/or compressible such that they do not interfere with the displacement 
of the contact members 16, 18, 20, and 22. Additionally, the filler 
elements 40 are fabricated such that they are impervious to moisture or 
ice. For example, in one specific embodiment, the filler elements 40 are 
fabricated in a mold as integrally skinned members of polyether 
polyurethane having an approximate pre-rise density of five pounds per 
cubic foot. Additionally, even though the material provides an integral 
skin that is impervious to moisture, it has been found beneficial to 
provide a surface coat of urethane lacquer to the filler elements 40. In 
other specific embodiments, the filler element 40 includes an outer 
periphery of integrally skinned composition with the internal portion 
either being hollow or filled with a suitable material such as foam which 
may be different than the integrally skinned polyether polyurethane. 
Accordingly, even when the contact assembly 10 is exposed to ice-forming 
environments, since the filler elements 40 provide an ice-excluding 
function, the contact members 16, 18, 20, and 22 are capable of 
displacement by engagement with the contact element 14. The displacement 
of each of the contact members 16, 18, 20, and 22 is determined by the 
differences between the dimension 50 of the contact element 14 and the 
spacing 52 of the contact members 16, 18, 20, and 22. 
As can be seen in FIGS. 3 and 4, the filler elements 40 are molded into a 
convenient shape to generally conform to the volume between the contact 
members 16, 18, 20, and 22 and the support structure 28. A widened portion 
48 is provided at the top of the filler element 40 to shield the interface 
of the filler element 40 and the inner face 31 of the contact support 28 
from the ingress of moisture. Provision is also made for totally enclosing 
the springs 24,26 and the spacers 30 by means of holes 42. Additionally, 
holes 44 are provided for passage of the fasteners 36. 
In a specific application, the contact assembly 10 as illustrated in FIGS. 
1-4 is suitable for use with a high-voltage switch with disconnect blade, 
for example, of the types as shown in U.S. Pat. Nos. 3,769,477, 3,588,406, 
4,112,268, and 4,481,387. However, it should be realized that the moisture 
and ice-excluding functions provided by the filler elements 40 of the 
present invention can be utilized for other contact assemblies including 
displaceable members or any other mechanism of varied environment which 
embodies movable members which are required to operate under ice-forming 
conditions. 
While there has been illustrated and described various embodiments of the 
present invention, it will be apparent that various changes and 
modifications will occur to those skilled in the art. For example, while 
the spaced-apart contact members 16, 18, 20, and 22 are disclosed for 
illustrative purposes, in other specific embodiments, the contact members 
are arranged in various contact arrays or patterns with filler elements in 
various appropriate shapes being provided to allow the necessary 
displacement of one or more of the contact members for suitable contact 
engagement. Thus, in the illustrative specific embodiment of FIGS. 1 and 
2, the contact members 16,18 do not necessarily require displacement if 
the contact members 20,22 are allowed appropriate displacement. Further, 
while the illustrative embodiment of FIGS. 1 and 2 depicts a movable 
contact 14 and a stationary contact structure carrying the contact members 
16, 18, 20, and 22, it should be realized that in other specific 
embodiments, the contact members 16, 18, 20, and 22 are movable and the 
contact element 14 is either movable or stationary. Additionally, in other 
specific embodiments, a single self-supporting contact element is provided 
that defines one or more contact members. For example, the contact members 
16,20 can be provided as a single self-supporting U-shaped element. It 
should also be realized that the present invention is applicable to other 
elements which require displacement space for operation whether on 
switches or other apparatus. It is intended in the appended claims to 
cover all such changes and modifications as fall within the true spirit 
and scope of the present invention.