Note: Descriptions are shown in the official language in which they were submitted.
CA 02481082 2004-10-18
SWITCHGEAR AND ENCLOSURE THEREFOR
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates generally to switchgear for the field of
electrical power
distribution, and more particularly to an enclosure for pad-mounted
installation of switchgear
to provide separate access to and isolation between medium-voltage cable
termination
arrangements and the low voltage control, testing and viewing provisions.
Description of the Related Art
Switchgear are generally categorized by their installation location (e:g.
grade or
surface, sub-surface etc.), the configuration of components (e.g. loadbreak
switches, fuses,
interrupters, disconnects, sectionalizers, etc.), the cable connections (e.g.
elbows, cable
terminators), the accessibility of components and controls, the medium within
the switchgear
enclosure, for example air, vacuum, oil, gas (such as SF6), etc., and
additional features such
as fault indicators, voltage indicators, power operation, automatic fault
interruption control,
etc. Various enclosures for pad-mounted installations are known that provide
security and
access features for operation of the switchgear or components housed therein.
For example,
see U. S. Patent Nos. 4,986,578, 4,489,966, and 3,572,062 for arrangements to
secure access
to pad-mounted gear.
While the enclosures of the prior art arrangements may be useful to provide
certain
useful operational features, the prior arrangements are rather limited
regarding accessibility,
ease of fabrication, and ease of operation for switchgear that is housed in a
sealed tank and that
includes arrays of low-voltage controls and viewing provisions of internal
switch positions, and
arrays of medium-voltage cable terminations. For example, the switchgear of U.
S. Patent
No. 5,521,567 would be extremely useful for pad-mounted installations if
suitable enclosures
were available.
CA 02481082 2004-10-18
S~TMMARY OF THE INYENTIO11~TT
Accordingly, it is a principal object of the present invention to provide
switchgear for
pad-mounted installations including an enclosure having improved access
features for operation
which provide large areas of access and also isolates low-voltage control
compartments from
the medium-voltage termination compartments.
It is another object of the present invention to provide an enclosure for pad-
mounted
installation of switchgear that includes features for efficient fabrication
while also providing
desirable security, access, and environmental features.
It is a further object of the present invention to provide an enclosure for
pad-mounted
gear that houses a sealed switchgear tank and includes lift-up cover panels
and removable
panels for access to low-voltage control and viewing provisions with isolation
from medium-
voltage cable termination provisions of the switchgear, and further provides
large degrees of
open access to the medium-voltage cable termination provisions without
obstruction.
It is yet another object of the present invention to provide security and
environmental
protection provisions for pad-mounted enclosures including lift-up cover
panels.
It is a still further object of the present invention to provide an enclosure
for pad-
mounted gear that includes collapsible lifting tab provisions.
These and other objects of the present invention are efficiently achieved by
the
provision of an enclosure for pad-mounted installation having large lift-up
cover panels in
combination with removable front panels so as to provide unobstructed access
to the interior of
the enclosure. In a preferred arrangement, the enclosure houses switchgear
that includes low
voltage control and viewing arrangements that are operable. from a first side
of the switchgear
and medium-voltage cable terminations that are accessible from a second side
of the switchgear
opposite the first side, the enclosure providing access to the low-voltage
arrangements while
providing isolation from the medium-voltage arrangements. The enclosure also
includes
protection from the environment in the area of the lift-up cover panels while
also providing
collapsible lifting members.
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BRIEF DESCRIPTION OF THE DRAWING
The invention, both as to its organization and method of operation, together
with
further objects and advantages thereof, will best be understood by reference
to the specification
taken in conjunction with the accompanying drawing in which:
FIG. 1 is a perspective view of the switchgear of the present invention for
pad-mounted
installation;
FIG. 2 is a right-side elevational view of the switchgear of FIG. 1 with parts
removed
for clarity;
FIG. 3 is a perspective view of the switchgear of FIG. 1 with lift-up cover
panels in the
open position;
FIG. 4 is a partial perspective view of the switchgear of FIGS. 1-3
illustrating
operation of a removable panel;
FIG. 5 is a perspective view of the switchgear of FIGS. 1-4 illustrating
access to a
medium-voltage compartment;
FIG. 6 is a partial left-side elevational view of the switchgear of FIG. 1
with parts
cutaway for clarity and partly in section illustrating structure of the lift-
up cover panel and the
removable panel;
FIG. 7 is a partial left-side elevational view of the switchgear of FIG. 1
illustrating
operation of the removable front panel;
FIG. 8 is an enlarged partial left-side elevational view of the switchgear of
FIG. 1 with
parts removed and cutaway;
FIG. 9 is a perspective view of the switchgear of FIG. 1 with parts removed
for clarity
illustrating protective features of the present invention;
FIG. 10 is an enlarged perspective view of portions of the switchgear of FIG.
3 to
better illustrate the features of the present invention;
FIG. 11 is a partial right-side elevational view of FIG. 8 with parts removed
for
clarity;
FIG. 12 is a front elevational view of a collapsible lifting member of the
switchgear of
FIGS. 1-11;
FIG. 13 is a diagrammatic representation of the assembly and interaction of
the features
of FIGS. 8 and 10-12 regarding collapsible lifting features;
FIGS. 14 and 15 are enlarged, partial left-side elevational views ;similar to
FIG. 6 and
illustrating operation of the switchgear;
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FIG. 16 is an enlarged; partial front elevational view of the switchgear of
FIG. 1;
FIG. 17 is a partial perspective view of the switchgear of FIGS. 1-16
illustrating a
panel holder arrangement;
FIG. 18~ is top plan view of FIG. 17;
FIG. 19 is a partial perspective view of a removable panel of the switchgear
of FIGS.
1-18;
FIG. 20 is a diagrammatic view of one of the removable panels of the
switchgear of
FIGS. 1-19;
FIG. 21 is a diagrammatic view of a second of the removable panels of the
switchgear
of FIGS. 1-19; and
FIG. 22 is an enlarged, partial front elevational view of FIG. 1 illustrating
a grounding
arrangement for the removable panel.
DETAILED DESCRIPTION
Referring now to FIGS. 1-5, the switchgear 10 of the present invention is a
self
contained structure designed for outdoor use and includes a self supporting
enclosure 12 for
pad-mounted installation. The enclosure 12 is suitable for housing a variety
of switchgear
configurations, providing desirable security, access and structural integrity
features. In a
specific embodiment as illustrated in FIG. 2, the enclosure 12 houses a
switchgear tank:. l4,
which in an illustrative embodiment is a sealed switchgear assembly, for
example of the type
shown in United States Patent Nos. 5,864,107, 6,040,538 and 6,114,642.
The switchgear tank 14 contains various electrical and mechanical components
and is
capable of being configured in a variety of circuit configurations to provide
desirable operating
features in an electrical .power distribution system. Specifically, the
switchgear tank 14 of
~(;, 2 includes a control panel having an array 16 of low-voltage control
arrangements l7 and
an array 18 of viewing windows 19 for viewing of the operational status of
switches contained
within the tank 14. The switchgear tank 14 also includes an array 20 of
termination
arrangements 21 for medium-voltage electrical cables. In accordance with
important aspects
of the present invention, the enclosure 12 includes access features for
operation which provide
large degrees of access and also isolates a low-voltage operating compartment
22 (FIGS. 2, 3
and 5) from a medium-voltage termination compartment 24 (FIGS. 2, 3 and 5).
Specifically, the enclosure 12 includes lift-up cover panel arrangements and
removable
panel arrangements. For example, in an illustrative embodiment, lift-up cover
panels 26 and
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28 and removable panels 30 and 32 are provided. As illustrated, the lift-up
cover panel 28 and
the removable panel 32 provide access to the low-voltage operating compartment
22 which in
the illustrative example houses the array 16 of low=voltage control
arrangements 17 and the
array 18 of viewing windows 19 with isolation from the medium-voltage
compartment 24
housing the cable termination arrangements 20 of the switchgear tank 14. The
cover panel 26
and the removable panel 30 provides large degrees of open access to the array
20 of medium
voltage termination arrangements 21 for handling these terminations and the
attached cables
via working tools, e.g. shotgun sticks or the like, free of obstruction. For
example, with the
cover panel 26 in the open position of FIG. 2 and with the removable panel 30
removed,
unobstructed access is available to the medium-voltage compartment 24 over
large areas and
angles of approach generally referred to at 25 in FIG. 2.
The enclosure 12 is defined by upstanding sidewalls, e.g. in the specific
illustration of
FIGS. 1-5, opposed sidewall panels 40, 42 spanned by structural panels or
members 44,46
along the front and back sides of the enclosure 12. The lift-up cover panels
26, 28 are
1S pivotally mounted via hinges 48 with respect to a support member 60 (FIGS.
3, 5) which
spans the sidewalls 40,42, and assists in providing strength and rigidity to
the overall enclosure
12. In accordance with important aspects of the present invention, a central
cap member 70
(FIG. 1) is located above the support member 60 and also spans the sidewalls
40,42. As will
be explained in more detail hereinafter, the cap member 70 functions to shield
the support
member 60 and the interior of the switchgear 10 from precipitation while the
support member
60 is arranged to divert and direct rain or the like out to the sides of the
switchgear 10 and
away from the interior of the switchgear 10. Additionally, and in accordance
with additional
important aspects of the present invention, the cap member 70 also includes
side members 80,
82 and cooperates with tab members 90, 92 to provide a collapsible lifting
arrangement for use
in lifting and moving the pad-mounted switchgear 10, which can also be
characterized as a
retractable arrangement and will be described in more detail hereinafter.
Turning now to a more detailed discussion of the access features of the
switchgear 10,
the lift-up cover panels 26, 28 interfit and cooperate with the removable
panels 30, 32
respectively to selectively provide access to the interior of the enclosure 12
and to the features
of the switchgear tank 14. The lift-up cover panels 26, 28 secure the panels
30, 32
respectively such that the panels 30,32 are secured in place until the
respective lift-up cover
panel 26, 28 is lifted clear of the respective removable panel 30,32.
In the specific embodiment of FIGS. 1-5 and with additional reference to FIGS.
d and
7, the turned edge 96 of the cover panels 26, 28 overhangs and traps the top
edge 98 of the
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panels 30,32 as seen in FIGS. 1 and 6. Further, a lower edge I02 of the panels
30, 32 in the
form of a lip interfits and is trapped behind the members 44, 46; as shown in
FIG. 7. When
the cover panel 26, 28 is lifted clear of the respective panel 30, 32, as
shown in FIG: 3, 'the
panel 30, 32 may then be lifted out and away from the enclosure 12 as shown in
FIGS. 4 and
7. As seen in FIG. 5, when the panels 30, 32 are removed, the top and front
surfaces to the
enclosure 12 are unobstructed over a wide area with only the top rail portions
110, 112
protruding from the sidewalls 42, 20 respectively. As seen in FIGS. 3,4 and 6,
the top edge
98 of the panels 30, 32 is supported by the top edge 114 of the top rail
portions 110, 112. In
this regard, the top edge 98 of the removable panels 30, 32 includes a turned
down edge or
flange at 116 except in the areas of the top rail portions 110, 112 to provide
additional
structural rigidity and support to the enclosure 12 and the panels 30, 32 when
the panels 30, 32
are in their normally closed positions. Accordingly, with the lift-up cover
panels 26, 28 in the
open position and the panels 30, 32 removed, open access to the interior of
the enclosure 12 is
provided over a wide range from the top and front as shown in FIG. 5.
Of course it should be understood that in the use of the switchgear of the
present
invention with the illustrative switchgear tank 14 housed therein, access is
provided to the low-
voltage operating compartment 22 as shown in FIG. 3 merely by lifting the
cover panel 28.
and the panel 32 need not be removed for operation of the controls 17 and use
of the viewing
windows 19. Further, the cover panel 26 to the medium voltage compartment 24
may be left
in the closed position as shown in FIG. I. Thus, the operator is not exposed
to any
components of the medium voltage compartment 24.
Referring now additionally to FIG. 19, the removable panels 30, 32 include a
section
31 that slopes inwardly so as to create a recess 33 (FIG. 6) in combination
with the lift-up
covers 26, 28 respectively where the lift-up covers 26, 28 overhang the
removable panels 30,
32 at the top edge 98. In this manner, space is created for a security latch
assembly 150 (IFIG.
6) and additionally, the recess 33 creates a convenient access to the
underside of the lift-up
covers 26, 28 for an operator to grasp and raise the lift-up covers. In this
regard, the
removable panels 30, 32 include a pin 35 (FIG. 19) at each end which extends
inwardly
toward the enclosure 12 and which is received by an aperture 111 (FIG: 4) of
the top rail
portions 110, 112. This retains the removable panels 30, 32 from being lifted
when the lift-up
panels 26, 28 are in place. Additionally, the removable panels 30, 32 also
include a threaded
retainer 37 (FIG. 19) which is threaded into threaded sleeve 113 (FIG. 4) of
the top rail
portions 110, 112. This further restrains the removable panels 30, 32 from
movement even
after the lift-up covers 26, 28 have been raised so as to free the removable
panels 30, 32.
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In a preferred embodiment, and referring additionally now to FIGS. 20 and 21,
the
panels 30, 32 are rendered non-interchangeable with each other on the
switchgear 10. For
example, as seen in FIG. 20, the panel 30 includes the pin 35 at a first
location 39 on the
removable panel 30, while as seen in FIG. 21, the removable panel 32 includes
a pin 35' at a
different location 41. Similarly, the apertures 111 are suitably arranged for
each of the pin 35,
35' at respective locations 39, 41. The non-interchangeable feature is useful,
where, for
example, different labeling, instructions etc. are provided on each of the
removable panels 30,
32.
With additional reference now to FIG. 22, a grounding arrangement 81 (location
in
FIG. 3) is provided for the removable panels 30, 32. For example, in a
specific embodiment,
a conductive spring plate 83 is secured to the top edge along the top edge 45
of each of the
members 44, 46 via a self tapping screw 85. This provides a suitable enclosure
ground at the
conductive spring plate 83. A self tapping screw 89 (also seen in FIG. 7) is
affixed to the
lower edge 47 of the removable panels 30, 32. Thus, with the removable panel
30, 32 in
place, a suitable ground is provided by the wiping contact between the
conductive spring plate
83 and the head of the screw 89. The conductive spring plate 83 in a specific
embodiment is
fabricated from' .025 inch thickness stainless steel with approximate
dimensions of 2.5 inches
along the edges 45 and 47 and 1.5 inches transverse thereto. The conductive
spring plate 83 is
also fabricated so as to extend at an angle sufficient to contact the screw 89
and establish
suitable contact force accounting for the maximum clearances between the edges
45, 47, i.e.
the angle of the portion 87 of the spring plate 83 is selected so as to be
greater than the
maximum angles encountered during operating conditions to contact the screw 89
and provide
suitable contact force to establish a suitable ground to the enclosure 12 via
the conductive
spring plate 83, the screw 85 and the members 44, 46. A suitable angle for the
fabrication of
the portion 87 of the conductive spring plate 83 has been found to be 15
degrees, the
dimensions in FIG. 22 being somewhat enlarged for illustration.
Turning now to a more detailed discussion of the provisions of the present
invention to
prevent the entry of precipitation and the like from ingress to the switchgear
10 in the vicinity
of the hinge areas at 48 of the lift-up cover panels 26, 28 and referring
additionally now to
FIGS. 8-10, the central cap member 70 is dimensioned to overlie portions of
the cover
members 26, 28 and includes downwardly turned edges to form flanges 120, 122
so as to
function as a hood or protective member over the areas of the hinges 48 and
the central
portions of the interior of the enclosure 12, thus serving to help prevent the
ingress of
precipitation and the like. Further, for the situations where some
precipitation may enter
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around the central cap member 70, the member 60 functions to support the
hinges 48 of the
lift-up cover panels 26, 28 and further includes turned up side edges that
form flanges 124,
126 so as to function as a directing and diverting channel or gutter. As shown
in FIG. 9, any
precipitation or the like entering the member 60 is directed out to the sides
of the enclosure 12
and down the exterior of the enclosure 12; as referred to at 128, I30. To this
end, the
sidewalls 40, 42 include slotted portions 132 at the center of the top edges
thereof. To aid in
preventing the ingress of precipitation etc., the cover panels 26, 28 include
upwardly turned
edges forming flanges 134, the cover 26 in the open position being shown at
26' in FIG. 8.
The flange 134 functions to prevent ingress to precipitation and other objects
in both the open
and closed positions of the cover panel 26, with any precipitation caught in
the areas of the
flange 134 being directed out to the sides of the enclosure 12.
In accordance with additional important aspects of the present invention, and
referring
additionally to FIGS. 11-13, the collapsible lifting arrangement is provided
by the tab
members 90, 92 which are slidable between extended and retracted positions
within the
respective side members 80, 82 of the central cap member 70 via openings 141
(FIG. 10)
between the side members 80, 82 and the central cap member 70. The extended
position of
the lifting tab members 90, 92 is shown in FIGS. 3, 5 and 10 and the retracted
position is
shown in FIGS. l and 13. The lifting tab members 90, 92 include a turned edge
forming a
grasping flange 139 by which the lifting tab members may be raised to their
extended position
by an operator and a lifting hole 140. As best seen in FIG. 11, the side
members 80, 82 of the
central cap member 70 include pins 146 (FIG. 13), 148 which are received
within slots 142,
144 of the lifting tab members 90, 92 (best seen in FIG. 12) for guiding the
lifting tab
members 90, 92 between the extended and retracted positions. Retention
hardware 149 is also
provided to retain the tab members 90, 92 on the pins 146, 148 and provide
appropriate
alignment and guidance.
Considering now in more detaul the security and access provisions of the
present
invention, and referring now to FIG. 6 and additionally to FIGS. 14-16, the
security latch
assembly 150 is carried by the lift-up cover panels 26, 28 and which is
actuated via a penta-
head bolt 152. The latch assembly 150 includes a cylindrical well portion 154
with inner
sidewall 156 and a shoulder 158. The penta-head bolt 152 is biased outwardly
via a spring
160 and retained by a collar 161 acting against the shoulder 158. An extending
portion 162 of
the penta-head bolt 152 moves to engage an aligned, threaded sleeve 164
carried by the
removable panels 30, 32. In the engaged position of FIG. 6, a shackle 166 of a
lock 168 may
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be inserted through apertures 170, 172 of the sidewall 156 of the well portion
154, whereupon
the shackle 166 blocks access to the penta-head bolt 152.
With reference to FIG. I4, the latch assembly 150 is shown in the disengaged
position
in which the lift-up panel 26 is capable of being lifted to the open position
since the penta-head
bolt 152 is not engaging the removable panel 26. To engage the latch assembly
150, as shown
in FIG. 15, the penta-head bolt 152 is moved inwardly via a penta-head socket
tool (not
shown) and turned one or more revolutions to engage the threaded sleeve 164 of
the removable
panel 30 whereupon the penta-bolt moves to the fully engaged position of FIG.
6. Note that in
partially engaged position of FIG. 15, the shackle of a lock may not be
inserted and locked,
such that the latch assembly 150 requires fully engaged operation and position
before the lock
can be inserted.
Referring again now to FIG. 2 and additionally to FIGS. 17 and 18, when the
lift-up
cover panels 26, 28 are lifted to an open position, a holder rod 180 is
inserted into an aperture
182 (FIG. 17) of a bracket 184 carried on the inside of the panel 26, 28. The
storage position
of the holder rod 180 is shown in FIG. 2 as 180' . As best seen in FIG. 17,
the holder rod 180
is pivotally carried with respect to the upstanding flange 186 of the
sidewalls 40, 42 for
movement between the stored position 180° and the holding position
shown in FIGS. 2 and 17.
With reference to FIG. 18 and in accordance with important aspects of the
present invention,
the rod 180 is pivotally carried with respect to the upstanding edge 186 of
the sidewall 40, 42
such that an end 188 of the holder rod 180 extends through an aperture 190 in
the upstanding
edge 186 and a collar 192 retains a spring 194 about the I80 and between the
collar 192 and
the upstanding edge 186, the collar I92 acting against a shoulder I96 on the
rod 180. Thus,
the rod 180 via the spring 194 serves to hold the cover panels 26, 28 in a
stable position in
response to forces such as wind acting against the panels 26, 28. As seen in
FIG. 18, the
spring 194 resists movement of the holder rod 180 in response to forces on the
panels 26, 28
that act to move the holder rod 180 out of the stable position, i.e. forces
acting on the panels
26, 28 to tend to move the panels 26, 28 with attendant movement of the holder
rod 180 act
against the spring 194 which the spring 194 resists. As seen in FIG. 18,
movement of the
holder rod 180 to the positions referred to at 197 and 198 are resisted since
the spring 194
requires forces to be exerted thereon for the positions 197 and 198.
While there have 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. Accordingly, it is intended in the appended claims to cover all
such changes and
modifications that fall within the true spirit and scope of the present
invention.
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