Electricity: conductors and insulators – Conduits – cables or conductors – With interior conductor or cable supports
Reexamination Certificate
2001-02-23
2003-02-18
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
With interior conductor or cable supports
C174S08800C, C174S068200, C174S07000A, C174S0720TR, C174S09900B, C174S14900R
Reexamination Certificate
active
06521837
ABSTRACT:
FIELD OF THE INVENTION
This invention relates to an electrical busway housing system capable of conducting electricity and mechanical connection means therefor, and more particularly, to an electrical busway housing system mechanically connected at the joints of adjoining housing sections by utilization of a coupling system having a top plate and a bottom plate, at least one of which has a roughened surface that provides superior gripping strength when the adjoining sections of busbar housing are clamped between them.
BRIEF DESCRIPTION OF PRIOR ART
Electrical busway, also known as elongated electrical distribution busway, is well known in the art. An electrical busway housing system is typically comprised of multiple pieces of track connected end to end with one or more electrically-isolated, conductive busbars fastened to the housing, such that the system is capable of conducting electricity end to end through the busbars. The busbar is adapted to permit electrical power tap-off at any point along the length of the busbar. Such busbar is often provided overhead, or may be provided along walls or flooring, and is used to distribute electricity to various take-off devices to equipment, appliances, lighting or other articles requiring a source of electrical energy to operate. For example, when installed in a home or office setting, it is often used to permit lighting and/or electrical sockets to be placed in one or more locations along the electrical busway. When installed in a factory or other industrial application, electrical sockets, lighting or other industrial devices may be placed on, near or along the busway to obtain electrical current from the busway.
Electrical power distribution tracks or busways are typically comprised of an elongated housing containing multiple electrically isolated conductive busbars. Sections of the track can be joined together to form long runs for the power distribution, and such sections may be of any length, but are generally anywhere from two (2) to twenty (20) feet long each. The joining of two twenty foot sections to one another, for example, provides 40 feet of electrical busbar, and the process can be repeated as necessary to provide electrical busway of substantial length.
While not limited to the use of aluminum housings, aluminum busbar housing generally tends to be the housing of choice due to its light weight, great strength and economical cost and ease of manufacture.
The joining of the individual sections must provide for making both mechanical and electrical connections from one section of housing to the adjoining section. This is generally accomplished with a coupler, also known, among other terms, as a coupling system, a connecting system, a coupling assembly, or a connector assembly. There are several known approaches to this coupling system. Examples include U.S. Pat. No. 2,969,421, to Sott, Jr; U.S. Pat. No. 3,210,716 to Meacham; U.S. Pat. No. 3,509,514 to Christensen et al.; U.S. Pat. No. 6,039,584 to Ross and U.S. Pat. No. 6,105,741 to Ross, with certain of these patents focusing on the mechanical connection, the electrical connection or both.
Referring now to
FIG. 1A
there is illustrated a coupling system of the prior art which uses a pair of flat plate connector assemblies
2
and
4
. Two sections of busway
6
and
8
, shown in phantom in
FIG. 1A
can be connected by using the two flat plate connector assemblies
2
and
4
, that sandwich a flange or similar feature at the ends
10
and
12
of the busway housing. Flat plate connector assemblies of the type of flat plate connector assemblies
2
and
4
are usually used in two sets, either top and bottom or side and side. Referring to both FIG.
1
A and
FIG. 1B
, such flat plate connector assemblies of the type of flat plate connector assemblies
2
and
4
are each composed of a flat bottom plate
14
having a pair of throughholes
16
therethrough which may or may not be threaded, and a corresponding top plate, in this case the u-shaped top plate
18
. The u-shaped top plate
18
includes throughholes
20
therethrough, which may or may not be threaded. Bolts
22
and
23
are typically inserted through the throughhole
20
and
21
respectively of u-shaped top plate
18
, and into the corresponding throughhole
16
and
17
in flat bottom plate
14
whereupon, if the throughhole of the flat bottom plate is threaded, said bolt threadably engages said threaded throughhole, allowing the bolt to be tightened in order to draw the u-shaped top plate and the flat bottom plate together over the flanges at the ends
10
and
12
respectively of the busways
6
and
8
. If the throughhole of the flat bottom plate
14
is not threaded, a nut
26
is threadably engaged with the bolt
22
to draw the flat bottom plate
14
and the u-shaped top plate
18
together. The frictional force between the flat bottom plate
14
, the u-shaped top plate
18
and the flange of the respective housings
6
and
8
is intended to keep the adjoining housings
6
and
8
from separating. However, under loads, particularly where the housings
6
and
8
are supported overhead and span a substantial distance, the housings
6
and
8
tend to pull apart overtightening bolts
22
to provide additional compressive force generally results in stripping the threaded throughholes or nuts damaging and/or destroying the connector assembly.
Referring now to
FIG. 2
there is illustrated a known wrap-around type connector
30
. In this design, an aluminum extrusion
32
telescopes over the ends of housings
6
and
8
shown in phantom that are joined. Wrap-around connector
30
has two bolts
34
and
35
that tighten a plate
36
to create a frictional clamping force as described above in connection with the flat plate coupling assemblies
2
and
4
. However, as may be appreciated, most of the support comes from the telescoping or wrap-a-round effect rather than the frictional clamping force.
Illustrated in
FIG. 3
is yet another known connector generally referred to as a channel and set screw connector
40
. An extruded piece of aluminum channel
42
is designed to slide loosely into each end of a pair of busbar housings
6
and
8
in phantom, where channels
44
and
46
engage corresponding lips on each of the busbar housings
6
and
8
. Once the busway housings
6
and
8
are butted together, and the connector
40
is centered over the gap interface between the two housings
6
and
8
, two or more setscrews
48
and
49
are tightened in throughholes through the connector
40
and through a corresponding channel in each housing corresponding to the lip
50
of the connector
40
in order to secure both the connector
40
and the two housings in place. Although the setscrews
48
and
49
keep the connector
40
from moving and the shape of the extrusion provides some support for keeping the two housings in line, particularly when the housings are supported overhead, the amount of gripping frictional force in this design to prevent separation of the housings is minimal.
All of the known embodiments described above suffer from the limitation that where the busbars housings are joined, particularly but not limited to larger busway systems (e.g. greater than 100 amps), where the busbar housings are installed overhead or along a wall the above described connectors provide insufficient force to hold the busbars tightly together. For example, this is particularly true for large busway systems supported overhead from a ceiling or other structure where the supports are placed at greater intervals from one another (e.g. 10 foot intervals versus 5 foot intervals). Greater spacing intervals between the supports is generally desired as fewer supports are needed to support the busway system as a whole, but as pointed out above, the known connectors between busway housing sections, particularly for the larger busway systems, cannot provide sufficient force to hold the busbar sections together over greater spacing intervals. For example, such designs typically cannot meet a United Laboratories Resistance to
Hilgert Brian Louis
Schultz Edward James
DKW Law Group, P.C.
Lee Jinhee J
Reichard Dean A.
Schnell Terry L.
Smith William P.
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