Patent Application
20060082264
The present invention relates generally to the field of electrical switchboards and panel boards and more particularly to a device that facilitates spacing, alignment, and mounting of electrical equipment in switchboard and panel board cabinets.
Distribution panel assemblies such as switchboards and panel boards are general terms which cover metal enclosures, housing switching and interrupting devices such as fuses, circuit breakers, associated controls, instrumentation and metering devices. Such assemblies typically include associated supporting structures, interconnections and bus bars used for the distribution of electrical power. Voltage in switchboards operate at voltages up to 600 volts and with continuous currents up to 5000 amps or higher. Such devices are also designed to withstand short circuit currents ranging up to 200,000 amps (3 phase rms symmetrical).
Typical distribution panel equipment is composed of a lineup of several metal enclosures (hereinafter referred to as sections). Each section may have several circuit breakers stacked one above the other vertically in the front of the section. Each section has a vertical or sectional bus which supplies current to the breakers within the section via short horizontal branch busses or straps. The vertical bus bars in each section are supplied with current by a horizontal main bus bar that runs through the lineup of sections. A typical arrangement includes bus bars for each electrical phase of a multi-phase system which may include three power phases and a neutral.
The bus straps typically are directly attached to the vertical bus sections. If the straps are large, they may require additional support. Standards organizations and other electrical codes require that minimum over-surface and through-air clearances (hereinafter referred to as “electrical clearance”) be maintained between the straps and all other conductive components in a switchgear assembly. In a typical configuration, the circuit breakers that attach to the bus straps may wholly rely on the bus strap for the circuit breaker mounting location and support or may require an additional device or structure for attaching to the mounting rails of the cabinet.
Thus there is a need for a strap support barrier for an electrical cabinet that provides spacing, alignment and mounting of electrical equipment, such as circuit breakers. There is also a need for an apparatus that will provide support for circuit breakers and provide an isolation of connecting bus straps from each other to comply with electric clearance requirements.
There is provided a strap support barrier for an electrical cabinet, with the electrical cabinet including vertical and horizontal bus bars. The strap support barrier includes a planar member. A mounting portion coupled to the planar member. A pair of spacing portions coupled to the planar member, wherein the planar member, mounting portion and spacing portion are configured to provide electrical clearances for the bus bars. The strap support barrier can also include orifices defined on the planar member to facilitate mounting of a strap to at least one vertical bus bar. Another embodiment of the strap support barrier includes at least one guide pin coupled to the planar member and configured to align the straps with the vertical bus bar.
There is also provided an electrical cabinet for electrical equipment. The electrical cabinet includes a housing including at least one pair of mounting rails mounted in the housing. At least one vertical bus bar mounted in the housing and a strap support barrier coupled to the mounting rails. The strap support barrier comprises a planar member, a mounting portion coupled to the planar member, and a pair of spacing portions coupled to the planar member. The planar member, mounting portion and spacing portion are configured to provide electrical clearances for the bus bars.
There is also provided an electrical equipment mounting kit for use in an electrical cabinet. The electrical cabinet includes a plurality of vertical bus bars and at least two mounting rails. The electrical equipment mounting kit includes a planar member configured to couple to the mounting rails with the planar member defining an orifice aligned with each vertical bus bar. A spacing portion is coupled to the planar member separating the orifices. A bus strap is configured to couple to the vertical bus bar through one of the orifices. Wherein, the planar member and spacing portion maintain pre-selected distances between the bus strap and the vertical bus bars. Another embodiment of the kit includes at least one guide pin coupled to the planar member and configured to align the strap with the vertical bus bar. A planar member is configured to support electrical equipment.
Before describing the exemplary embodiments of a strap support barrier for electrical equipment in a distribution panel enclosure assembly, several comments are appropriate. Switchboard assemblies and panel board assemblies typically include vertical (section) bus bars to distribute electrical power within the assemblies. In a short circuit condition, extreme magnetic forces are created in bus bars as a result of the short circuit currents up to and including 200,000 amps symmetrical rms flowing through such bus bars. In a three phase power system (typically) as the short circuit currents flow through such bus bars, magnetic forces between adjacent bus bars tend to move such bus bars laterally (perpendicular) to the current flow. Such movement of the bus bars is typically prohibited or inhibited to avoid damage in arcing within enclosures by bus assemblies or arc barriers and equipment arrangements within the cabinet.
Referring now to the figures,
Referring now to
As illustrated in
Strap support barrier 30 includes orifices 45 defined on the planar member 32 to facilitate mounting of a bus strap 40 to at least one vertical bus bar 14. The orifices 45 can be of any suitable configuration but typically are large enough to accommodate installation of the bus straps 40 as illustrated in
The guide pins 50 function to locate and latch the bus straps 40. The guide pins 50 enable a quick, efficient construction of a sub-assembly, comprised of the strap support barrier 30 and bus straps 40. Such sub-assembly can be shipped as a single entity for easy user installation, retrofits, or upgrades in the field. It should be understood that other guiding configurations are contemplated, for example, stakes with a hook feature, pegs, spaced apart ridges or similar structures.
The planar member 32, mounting portion 34, and spacing portions 36 can be composed of any suitable material that is non-metallic and non-conductive electrically. The mounting portion 34 and spacing portion 36 can be integral with the planar member 32 as a single piece.
To mount electrical equipment 20 such as a circuit breaker (See
The bus straps 40 are configured to couple directly to the electrical equipment, such as a circuit breaker 20 with the circuit breaker mounted to mounting holes 44 provided in the strap support barrier 30 with fasteners 46 (See
Thus, there is provided a strap support barrier for an electrical equipment that provides guidance, securement, and phase isolation in a single device for mounting electrical equipment in the switchgear cabinet. The foregoing description of embodiments have been presented for purposes of illustration and description. It is not intended to be exhaustive nor to be limited to the precise forms disclosed, and modifications and variations are possible in light of the above teachings and may be acquired by practice of the invention. The embodiments are chosen and described in order to explain the principles and practical application to enable one skilled in the art to utilize the strap support barrier in various embodiments and with various modifications that are suited to the particular use contemplated. It is intended that the scope of the strap support barrier be defined by the claims appended hereto and their equivalents.
