U.S. patent application number 09/919481 was filed with the patent office on 2002-02-21 for bus connection access panel.
Invention is credited to Cook, James H., Muse, Peter D., Soares, Gilbert A..
Application Number | 20020021548 09/919481 |
Document ID | / |
Family ID | 24091342 |
Filed Date | 2002-02-21 |
United States Patent
Application |
20020021548 |
Kind Code |
A1 |
Muse, Peter D. ; et
al. |
February 21, 2002 |
Bus connection access panel
Abstract
An access panel located in a motor control center for inspecting
and accessing various bus connections, for example, a particular
phase vertical to horizontal bus connection or a horizontal bus bar
splice connection. The surface of the panel includes one or more
apertures positioned to align with one or more bus bar connections.
Covers are pivotally mounted along the surface of the panel
adjacent to the apertures in order to access and isolate the bus
connections within the motor control center. The cover is mounted
to the surface of the panel such that it can be moveable between
open and closed positions.
Inventors: |
Muse, Peter D.; (Durham,
NC) ; Cook, James H.; (Wilimington, NC) ;
Soares, Gilbert A.; (Mebane, NC) |
Correspondence
Address: |
CANTOR COLBURN, LLP
55 GRIFFIN ROAD SOUTH
BLOOMFIELD
CT
06002
|
Family ID: |
24091342 |
Appl. No.: |
09/919481 |
Filed: |
July 31, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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09919481 |
Jul 31, 2001 |
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09524959 |
Mar 14, 2000 |
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Current U.S.
Class: |
361/641 |
Current CPC
Class: |
H02B 1/14 20130101; H02B
1/21 20130101 |
Class at
Publication: |
361/641 |
International
Class: |
H02B 001/26 |
Claims
What claimed is:
1. A panel suitable for providing access to a plurality of bus bar
connections, the panel comprising: a surface having an aperture
disposed therein, said aperture is positioned to align with a
single bus bar connection; and a cover pivotally mounted to said
surface from a point adjacent to said aperture, said cover is
pivotable between an open position for providing access to said
single bus bar connection and a closed position wherein said cover
covers said aperture.
2. The panel of claim 1 wherein said cover is made of an
electrically insulating material.
3. The panel of claim 1 wherein said cover is made of a transparent
material.
4. The panel of claim 1 further comprising: a snap-fit fastener
coupled to said cover, said snap-fit fastener is received within a
first opening in said surface for pivotally mounting said cover to
said surface.
5. The panel of claim 1 further comprising: a boss extending
outwardly from said cover and configured for insertion into said
aperture, said boss releasably retaining said cover in the closed
position.
6. The panel of claim 1 wherein said surface is made of a
transparent material.
7. The panel of claim 1 wherein said surface is made of an
electrically insulating material.
8. The panel of claim 1 wherein said cover is pivotally mounted to
said surface by attachment hardware coupled to said cover and said
surface.
9. A motor control center, comprising: a bus bar system including a
plurality of bus bar connections; and a cabinet having a back wall,
first and second opposing sidewalls, first and second opposing end
walls and a front wall which substantially completely covers and
protects said plurality of bus bar connections from access when
closed, said front wall including: a panel, a surface of said panel
having an aperture disposed therein and positioned to align with a
single bus bar connection in said plurality of bus bar connections,
and a cover pivotally mounted to said surface from a point adjacent
to said aperture, said cover is pivotable between an open position
for providing access to said single bus bar connection and a closed
position wherein said cover covers said aperture.
10. The motor control center of claim 9 wherein said cover is made
of an electrically insulating material.
11. The motor control center of claim 9 wherein said cover is made
of a transparent material.
12. The motor control center of claim 9 further comprising: a boss
extending outwardly from said cover and configured for being
inserted into said aperture, said boss retaining said cover in the
closed position.
13. The motor control center of claim 9 further comprising: a snap
fit fastener coupled to said cover, said snap-fit fastener is
received within a first opening in said surface for pivotally
mounting said cover to said surface.
14. The motor control center of claim 9 wherein said surface is
made of a transparent material.
15. The motor control center of claim 9 wherein said cover is
pivotally mounted to said surface by attachment hardware coupled to
said cover and said surface.
16. The motor control center of claim 9 wherein said surface is
made of an electrically insulating material.
17. A panel suitable for providing access to a plurality of bus bar
connections, the panel comprising: a surface having an aperture
disposed therein and positioned to align with one or more bus bar
connections; and a cover made of a transparent material and
pivotally mounted to said surface from a point adjacent to said
aperture, said cover moveable between an open position and a closed
position and configured to cover said aperture in the closed
position.
18. The panel of claim 17 wherein said cover is made of an
electrically insulating material.
19. The panel of claim 17 wherein said cover snap-fits within a
first opening in said surface so as to rotatably mount said cover
thereto.
20. The panel of claim 17 further comprising: a boss extending
outwardly from said cover and configured for insertion into said
aperture, said boss retaining said cover in the closed
position.
21. The panel of claim 17 wherein said surface is made of
transparent material.
22. The panel of claim 17 wherein said surface is made of an
electrically insulating material.
23. A panel suitable for providing access to a plurality of bus bar
connections, the panel comprising; a surface having an aperture
disposed therein and positioned to align with a single bus bar
connection; and a cover pivotally mounted to said surface and
moveable between an open position and a closed position, wherein
said cover rotates in a plane parallel to said surface.
24. The panel of claim 23, wherein said cover is equipped with a
snap-fit fastener.
25. The panel of claim 24, wherein said snap fit fastener includes
a fastener tip having a larger diameter than a neck of said
snap-fit fastener.
26. The panel of claim 25, wherein said snap fit fastener is
located behind said surface when said cover is installed.
27. The panel of claim 23, wherein said cover is equipped with a
position holding support.
28. The panel of claim 27, wherein said position holding support is
located within said aperture when said cover is in said closed
position and aligns said cover in said aperture.
29. The panel of claim 28, wherein said position holding support
has a support tip located adjacent edge of said aperture when said
cover is in said closed position.
30. The panel of claim 23, wherein said cover is capable of at
least one hundred eighty degrees of rotation.
31. The panel of claim 24, wherein said cover is capable of three
hundred and sixty degrees of rotation.
32. A panel suitable for providing access to a plurality of bus bar
connections, the panel comprising: a surface having a first
aperture and a second aperture disposed therein, said first
aperture is positioned to align with a first bus bar connection in
said plurality of bus bar connections, said second aperture is
positioned to align with a second bus bar connection in said
plurality of bus bar connections; a first cover pivotally mounted
to said surface at a point adjacent to said first aperture, said
first cover rotates in a plane parallel to said surface to allow
access to said first bus bar connection; and a second cover
pivotally mounted to said surface at a point adjacent to said
second aperture, said second cover rotates in a plane parallel to
said surface to allow access to said second bus bar connection.
33. The panel of claim 32 wherein said cover is made of a
transparent material.
34. The panel of claim 32 further comprising: a first snap-fit
fastener coupled to said first cover, said first snap-fit fastener
is received within a first opening in said surface for pivotally
mounting said first cover to said surface.
35. The panel of claim 32 further comprising: a boss extending
outwardly from said first cover and configured for insertion into
said first aperture, said boss releasably retaining said cover in
the closed position.
36. The panel of claim 32 wherein said surface is made of a
transparent material.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 09/524,959, filed Mar. 14, 2000, which is
incorporated by reference herein in its entirety.
BACKGROUND OF THE INVENTION
[0002] The present invention relates generally to access panels and
more specifically to an access panel in motor control centers to
inspect bus bar connections.
[0003] Motor control centers are commonly employed for performing
various protection and control functions in industrial settings. In
such motor control centers, three-phase electric power is fed from
electric power distribution mains to the motor control center
through a main circuit breaker within the control center. Within
the motor control center housing, internal electric power is fed
from the main circuit breaker to control center electrical
components through horizontal and vertical main bus conductors.
Electrical power is then fed through the bus conductors to internal
electrical components mounted within the drawers or buckets. The
buckets contain devices such as one or more circuit breakers,
starters, overload protectors, or pilot devices. Electrical
connection between the main vertical bus conductors and between the
main circuit breaker and the main vertical bus conductors and the
distribution bus conductors require suitable attachment hardware
such as bolts. Further, high contact pressure is necessary to
obtain a good electrical connection.
[0004] Bus conductors usually extend within a control center
enclosure where the respective electrical connections are made. The
associated buses are arranged within the control center enclosure
and accessed by means of a cabinet or panel positioned on the front
wall of the enclosure. Such enclosures have fixed back, side and
top walls.
[0005] Where bolts are used to maintain bus to bus connections, the
torque of the bolts must be checked periodically to assure the
integrity of the connection. A loss of torque in the connection can
lead to unwanted heat rise. Excess heat may also cause condensation
and corrosion. It is also desirable to visually inspect energized
connections while maintaining a safety barrier between connection
and personnel. Further, it is desirable to measure the temperature
of individual energized connections during operation without
exposure of personnel to a high voltage connection.
[0006] Access panels of the prior art have provided access to bus
connections by the use of sliding or pivoting panels that open to
expose more than one phase of the current. Therefore, personnel
cannot isolate one connection at a time but rather must expose more
than one phase. In the prior art, an insulating barrier is not
maintained during non-contacting temperature measurement nor is
such barrier maintained during visual inspection. In order to
visually inspect the high voltage connections, the panel must be
opened which does not provide any insulating barrier between the
connection and the personnel.
BRIEF SUMMARY OF THE INVENTION
[0007] In an exemplary embodiment of the invention, an access panel
made of an electrically insulating material comprises a surface
having a plurality of apertures disposed therein, with the
apertures positioned to align with one or more bus bar connections.
A plurality of covers is pivotally mounted on the surface of the
panel from a point adjacent to the apertures, each aperture having
one corresponding cover. The covers are configured to be moveable
between an open and closed position. In the open position, the
covers are pivotally rotated to provide access to the aperture. The
positional relationship of the apertures and respective covers
along the surface of the panel determines the access to at least
one bus connection.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a front perspective view of a motor control center
employing the access panel of this invention;
[0009] FIG. 2 is a front view of an access panel of the present
invention;
[0010] FIG. 3 is a side view of the cover of FIG. 2;
[0011] FIG. 4 is an alternative embodiment of the cover of FIG.
3;
[0012] FIG. 5 is a front view of an alternative embodiment of the
access panel of FIG. 2; and
[0013] FIG. 6 is an isometric view of an alternative embodiment of
the cover of FIG. 3.
DETAILED DESCRIPTION OF THE INVENTION
[0014] Referring to FIG. 1, a motor control center 10 is
illustrated. The motor control center 10 consists of a metallic
enclosure cabinet 12 including a top 30, a bottom 32, a back wall
34, two opposing side walls 38 and 40 and a front wall 36. The
front wall 36 of cabinet 12 includes buckets 16 which house various
internal electrical components such as one or more circuit
breakers, starters, overload protectors, or pilot devices. Unless
the top 30 or back wall 34 is disassembled, access to the internal
electrical components is by corresponding handle operators 17
extending through slots 18 located within the respective bucket
16.
[0015] The motor control center 10 generally provides control and
communication between the internal electrical components and an
external electrical distribution system. The top 30 includes
openings 14 to accept incoming power cables 15. The front wall 36
includes an access panel 68 providing access to a typical three
phase bus bar system. While a three phase bus bar system is shown,
the present invention is not limited to this configuration but may
be applied to other configurations, such as one, two or four phase
bus bar panel assemblies. Horizontal main bus conductors 42, 44 and
46 (shown in phantom) and vertical main bus conductors 48, 50 and
52 (shown in phantom) are located within cabinet 12. It is noted
that there are vertical and horizontal bus conductors for all three
phases. Three phase electric power is fed from the electrical power
distribution system to the motor control center 10 through power
cables 15 connected to a main circuit breaker 22. The internal
electric power is fed from the main circuit breaker 22 to the
internal electrical components through the horizontal bus
conductors (bars) 42, 44 and 46 and the vertical bus conductors
(bars) 48, 50 and 52. The vertical bus conductors 48, 50 and 52
connect the horizontal bus conductors 42, 44 and 46 to the internal
electrical components housed within the motor control center 10.
Ground bus bar 20 generally provides a common ground connection for
buckets 16. Internal electrical components are generally protected
by one or more circuit breakers 22.
[0016] Referring to FIG. 2, an enlarged view of the access panel 68
is shown. The panel 68 is constructed of a single panel and
preferably fabricated from an electrically insulating material such
as polymer material. The panel 68 provides access to various bus
connections that are located within the motor control center 10,
for example, a particular phase vertical to horizontal bus
connection 62, 78 or 80 or a horizontal bus bar splice connection
64. Vertical to horizontal bus connections 62, 78 and 80 and
horizontal bus bar splice connection 64 are typically fastened by
means of bolts 66. The panel 68 can be of various sizes and shapes
in order to accommodate a particular bus connection layout within a
motor control center 10. Further, the panel 68 may provide access
to one or more vertical to horizontal bus connections 62, 78 and
80, one or more horizontal bus bar splice connections 64 or any
combination thereof.
[0017] Panel 68 includes a surface 72 that forms a portion of the
front wall 36 of the cabinet 12 of the motor control unit 10. The
panel 68 also includes a cover 54 mounted along the surface 72. The
cover 54 is positioned so as to align with a corresponding aperture
56 thereby permitting access to one or more bus bar connections.
For example, cover 54 can align with the horizontal bus bar splice
connection 64 or with the vertical to horizontal bus connection
62.
[0018] The access panel 68 may also include multiple covers 54,
with each cover 54 aligning with an aperture 56 disposed in surface
72 of panel 68. Each aperture 56 aligns with one or more horizontal
bus bar splice connections 64 or with one or more phases of
vertical to horizontal bus connections 62, 78 and 80. It will be
appreciated that a plurality of apertures 56 and corresponding
covers 54 can be selectively aligned over bus connections within
the panel 68 thereby permitting visibility and access to the bus
connections without exposing all the bus connections located within
the panel 68.
[0019] Covers 54 each have a snap-fit fastener 94 proximate one end
and a handle 58 proximate an opposite end. Each cover 54 is
pivotally engaged at one end to the surface 72 of the panel 68,
allowing the cover 54 to pivot from an open position 70 to a closed
position 76. Further, each cover 54 and aperture 56 are of a size
and shape large enough to receive a fastening tool, such as a
socket wrench, to check the torque on bolt 66 or other similar
fastening means. Thus, each cover 54 allows access to a single bus
connection without unnecessary personnel exposure.
[0020] In the closed position 76, the cover 54 overlays the
aperture 56, thereby preventing unplanned exposure to an electrical
connection. The cover 54 can be pivotally rotated to the open
position 70 to expose the aperture 56. As shown in FIG. 2, the
cover 70 is in the open position exposing the aperture 56 through
which a bus connection 62, 64, 78 or 80 is visible and
accessible.
[0021] The cover 54 is made of an electrically insulating material.
Preferably, cover 54 is made from a transparent,
electrically-insulating material. Typically, individual bus
connection heat rise measurement is permitted with the use of
non-contact temperature measurement equipment, for example an
infrared temperature measurement instrument. By using a
transparent, electrically-insulating material for the cover 54, a
temperature measurement can be obtained without opening the cover
54 to expose the high voltage connection. Thus, the cover 54
permits visual inspection and non-contact temperature measurement
of bus connections while maintaining an insulating barrier between
the personnel and the energized bus connection. Also, when the
cover 54 is in the open position 70, the aperture 56 is exposed
thereby permitting personnel to check the bolt torque on the
respective de-energized bus connection by placing an appropriate
tool though the aperture 56.
[0022] Referring to FIGS. 2 and 3, cover 54 is attached to the
surface 72 of the panel 68 by means of a molded snap-fit fastener
94, preferably made of an electrically insulating material. The
molded snap-fit fastener 94 is inserted into a corresponding first
opening 100 on the surface 72 of the panel 68 so as to rotatably
mount the cover 54 to the surface 72. The cover 54 also includes a
position holding support 90, such as a boss, extending outward from
the cover 54. The position holding support 90 is shown in phantom
in FIG. 2. The position holding support 90 is configured for being
inserted into the aperture 56 threreby retaining the cover 54 in
the closed position 76. In the closed position 76, vibratory
movement of the cover 54 and unplanned exposure of personnel to one
or more bus connections is prevented.
[0023] Referring now to FIGS. 2 and 4, an alternative embodiment
for the snap-fit fastener 94 is shown. The cover 54 is attached to
the surface 72 by attachment hardware 74, such as a rivet, hinge or
slide, so that the cover 54 can be opened to expose the aperture
56. Preferably, the attachment hardware 74 is made of an
electrically insulating material.
[0024] Referring to FIG. 5, an alternative embodiment of the
present invention is shown. The access panel 101 includes a surface
108 that forms a portion of the front wall of cabinet of the motor
control center 10 as described for access panel 68. The panel 101
also includes multiple rectangularly shaped apertures 106 aligned
with one or more bus bar connections. A cover 110 having a shape
substantially the same as aperture 106 is secured adjacent each
aperture 106 so as to align with the aperture 106 when the cover
110 is in the closed position 105. It will be understood that the
shape of the aperture 106 can be modified to any number of
geometric shapes such as circles, ellipse, squares, rectangles and
the like so long as the aperture provides access to the bus bar
connections within motor control center 10.
[0025] Cover 110 is secured to the panel 101 using attachment
hardware 118 that penetrates an opening 116, located within the
cover 110 and a corresponding hole (not shown) in the panel 101
when the cover 101 is properly aligned with an aperture 106. The
attachment hardware 118 secures cover 110 to the panel 101 so that
the cover 110 can be pivotally rotated about the attachment
hardware 118. It will be recognized that the attachment hardware
118 can be in the form of a rivet, bolt, screw and the like so long
as the attachment hardware 118 allows the pivotal rotation of the
cover 110 as described herein. In one embodiment the attachment
hardware 118 is made of an electronically insulating material to
reduce the potential that a short circuit could be caused due to
inadvertent contact between metallic attachment hardware 118 and
energized components within the motor control center 10.
[0026] In a preferred embodiment, the cover 110 has at least one
hundred twenty degrees of rotation. In a most preferred embodiment
the cover 110 has at least three hundred and sixty degrees of
rotation. The greater the freedom of rotation of cover 110 the more
adaptable the cover 110 is for use with surface mounted electrical
control devices that a user may choose to mounted on surface 108.
Further, the greater the available rotation of cover 110 the
greater access is provided for the bus bar connections located
behind the panel 101.
[0027] The invention is ideal for applications that have limited
working space in front of the panel, because the cover can moved
between the open position 104 and closed position 105 without
having to move the cover in a direction perpendicular to the
surface 108, to any significant degree. Thus, the invention is
ideal for use in motor control centers.
[0028] Alternatively, the cover 110 can include a molded snap fit
fastener 94, as shown in FIG. 3 for the first embodiment. As shown
in FIG. 3, the neck 92 of the snap fit fastener 94 is narrower than
the fastener tip 93. To install a cover having a snap fit fastener
94, the cover 110 is aligned with the aperture 106 so that the snap
fit fastener 94 aligns with a first opening 100 located in the
surface 108 just above aperture 106. The first opening 100 is just
large enough to allow the fastener tip 92 to be forced through the
first opening 100 by pressing the cover 110 toward the panel 101.
When the cover is fully installed, the fastener tip 92 is located
behind the surface 108 of the panel 101 and the narrow neck 93 of
the snap fit fastener 94 comes to rest within the first opening
100. The diameter of the neck 93 allows the cover 110 to pivot at
least 180 degrees around the first opening 100 in a plane parallel
to the surface 108. The previously described range of embodiments
related to the freedom of rotation of cover 110 applies a cover
equipped with a snap-fit fastener 94. The snap fit fastener 94 can
be integrally molded as part of the cover 110 to increase the
strength and durability of the cover.
[0029] The cover 110, too, can be made of electrically insulating
material in order to maintain an insulating barrier between
personnel and the energized bus bar connections. In one embodiment,
the cover 110 is made of transparent, electrically insulating
material. A cover 110 made of transparent material permits visual
inspection and non-contact temperature measurement of the bus
connections. It will be understood that the cover can be made out
of any material such as polycarbonate and the like so long as the
material is both electrically insulating and transparent. Although
the close 110 is rigid, it must also flex longitudinally as
described herein. The advantages provided by a flexible cover are
also described herein.
[0030] Referring to FIG. 6, the cover 110 includes a handle 115 in
the form of a lip protruding from the bottom of the cover 110 at
approximately a ninety degree angle from the body 112 of the cover
110. The handle 115 allows the cover 110 to be grasped and be
repositioned during use. One advantage of the handle 115 shown in
FIG. 6 is that it is formed as an integral part of the cover 110.
The one-piece construction of the cover 110 and handle 115 creates
a stronger and more durable unit and reduces steps in the
manufacturing process.
[0031] FIG. 6 shows two position holding supports 114 located on
the back of cover 110. In the embodiment shown in FIG. 6, each
position holding support 114 curves upward toward the edge 107 of
the cover 110 and ends in a support tip 113. The location of the
position holding supports on the back of the cover 110 places them
within the aperture when the cover is in the closed position 105
and insure that the cover 110 is properly aligned within the
aperture 106. The support tips 113 are adjacent the sides of the
aperture 106 thereby preventing lateral movement of the cover 110
when in the closed position 105, FIG. 5. Lateral motion is
prevented because the position holding supports create an
interference that strikes edge 107 of the aperture 106 if the cover
110 shifts laterally while in the closed position 105.
[0032] As shown in FIG. 5, the cover 110 is moved between the
closed position 105 and the fully open position 104 by grasping the
handle 115. The bottom of the cover 110 is pulled slightly away
from the surface 108 in a direction substantially perpendicular to
the surface 108. The cover 110 remains attached to panel 101 by the
attachment hardware 118 but flexes away from the panel at the
handle end. The flex allows the position holding support 114 to
clear the edge 107 of the aperture 106. The cover 110 can then be
rotated in either a clockwise direction from the closed position
105 to the partially open position 103 and then to the fully open
position 104, if desired.
[0033] Accordingly, the access panel 68 of this invention provides
new concepts suitable for use in motor control units to enable an
increase in range of useful operation by providing safeguards for
both personnel and equipment. The access panel of this invention is
readily adaptable to a variety of operating conditions, motor
control centers or other similar enclosures containing high voltage
electrical connections for which access to and inspection of is
desirable.
[0034] While the invention has been described with reference to a
preferred embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the
essential scope thereof. Therefore, it is intended that the
invention not be limited to a particular embodiment disclosed as
the best mode contemplated for carrying out this invention, but
that the invention will include all embodiments falling within the
scope of the appended claims.
* * * * *