Electricity: conductors and insulators – Boxes and housings
Utility Patent
1998-11-09
2001-01-02
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Boxes and housings
C174S0720TR, C174S07100B, C174S07000A
Utility Patent
active
06169248
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to low voltage electric power distribution apparatus such as switchgear assemblies in which a plurality of cabinets housing electric power switching devices are mounted side-by-side with a set of common bus bars extending through them. In particular, it relates to supports for bus bars extending transversely through barriers between side-by-side cabinets.
2. Background Information
Switchgear assemblies include electrical switching apparatus for electric power distribution systems mounted in metal cabinets. Such electrical switching apparatus can include circuit breakers and network protectors which provide protection, disconnect switches for isolating parts of the distribution system, and transfer switches for connecting the distribution system to alternative power sources. The electrical apparatus can also include instrumentation such as metering equipment. Switchgear operating at voltages up through 600 volts are categorized as low voltage switchgear.
It is common in such low voltage switchgear to mount a plurality of cabinets each housing electrical power distribution apparatus side-by-side with a common cross bus extending transversely through and serving all of the cabinets. The cabinets are fabricated with metal frames. Applicable codes require that barriers be provided between side-by-side cabinets housing circuit breakers to reduce the likelihood that arcs could propagate along the cross bus from cabinet to cabinet. Often times, bus conductor profiles and their associated sorts make it difficult to effectively achieve this requirement due to the geometry involved. Small gaps are often produced which makes it cumbersome, and in some cases impossible, to shield these areas. For instance, the bus bars must be spaced from the metal frame which supports them to provide the required electrical isolation. Also, the supports must be sufficiently robust to withstand the sizeable magnetic forces produced by short circuits. The barriers which are slid between adjacent cabinets have cutouts to accommodate the bus bar and this offset. This produces gaps which have remained unsealed.
There is a need therefore, for improvement in switchgear assemblies, and in particular, in the arrangements for mounting the cross bus and for interfacing with the barriers between adjacent cabinets.
SUMMARY OF THE INVENTION
This need and others is satisfied by the invention which is directed to switchgear assemblies in which a plurality of cabinets having metal frames are mounted side-by-side with planar insulative barriers extending at least partially between the metal frames of adjacent cabinets. The switchgear assembly further includes at least one bus bar extending transversely through at least the two adjacent cabinets. A support for the bus bar comprises a molded body having a support mounting surface and a bus bar mounting surface spaced from the support mounting surface. First fasteners secure the molded body with the support mounting surface bearing against the metal frame of one of the cabinets. Second fasteners secure the bus bar to the bus bar mounting surface of the molded body with the bus bar spaced by a gap from the metal frame to which the molded body is secured. The planar barrier has a cutout aligned with this gap and through which the bus bar extends into the second cabinet. The molded body further has a barrier surface which extends across the gap between the bus bar and the metal frame and blocks the cutout in the barrier. The molded body preferably has flanges projecting adjacent the barrier surface which overlap and bear against the planar barrier adjacent the cutout. The support mounting surface and the bus bar mounting surface form parallel planes with the barrier surface of the molded body substantially perpendicular to both the support mounting surface and the bus bar mounting surface.
Preferably, the support mounting surface and the bus bar mounting surface of the molded body are offset in their respective parallel planes and the molded body has a first recess behind the support mounting surface in which the first fasteners are seated and a second recess adjacent the first recess and behind the bus bar mounting surface in which the second fasteners are seated. A partition separates the first and second recesses and therefore provides electrical isolation between the first and second fasteners. Preferably, a wall of the first recess also forms the barrier surface.
An additional bus bar support is mounted to the metal frame of the adjacent cabinet by third fastener means. Fourth fastener means secure the bus bar to the bus bar mounting surface of the additional bus bar support. The barrier surfaces of the two bus bar supports confront each other through the cutout. The flanges on the two bus bar supports overlap opposite sides of the planar barrier and are recessed relative to the barrier surfaces to form grooves in which the planar barrier is received. The invention also embraces the mounting support as described.
REFERENCES:
patent: 2930020 (1960-03-01), Powell
patent: 4921191 (1990-05-01), Herschler et al.
patent: 5213518 (1993-05-01), Weidler
patent: 5530205 (1996-06-01), Parks et al.
Bartholomew John Stewart
Rowe Neal Edward
Walker Steven Dale
Wilkie, II William Edward
Eaton Corporation
Moran Martin J.
Reichard Dean A.
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