Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electrical power distribution systems and devices
Reexamination Certificate
2000-03-31
2001-10-09
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electrical power distribution systems and devices
C361S611000, C361S624000, C361S639000
Reexamination Certificate
active
06301094
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to a drawout unit, and, more particularly, to a load/line terminal unit configured to make more efficient use of the space within the drawout unit.
In a motor control system, vertical bus bars which carry current to motor controller units are arranged vertically in drawout units. Sliding stabs usually plug into a housing with opposing prongs being biased toward each other on the sliding stabs to contact either side of the bus bars, whereby the electrical connection between the motor controller unit and the bus bars is maintained. Lugs on the sliding stabs are connected to bus straps extending from the lugs to the line side of a circuit interrupting device such as a circuit breaker. Bus straps also extend from the load side of the circuit interrupting device to the line side of a distribution power load circuit, such as a starter.
Load terminals are electrically connected to the load side of the distribution power load circuit and are typically positioned to allow an output cable to be connected to them in a vertical configuration. These load terminals are generally bushings positioned on the bottom of the distribution power load circuit and have an axially threaded terminal to which output cable connections are made. Alternately, output cables of a thinner diameter may have attachments on one end that allow them to be secured to load terminals with screws or bolts. One particular method of securing output cable to a load terminal, as described in U.S. Pat. No. 4,154,993 entitled “Cable Connected Drawout Switchgear”, involves mounting circuit equipment on a rolling carriage such that the load terminals engage connectors on stationary cables when the carriage is rolled over the cable connectors. Another method described in U.S. Pat. No. 5,107,396 entitled “Circuit Breaker Combined Terminal Lug and Connector” involves sliding a cable connector disposed axially on the end of a cable into a receiving slot on a terminal lug. Both of these methods of attaching output cable are such that the output cable depends vertically, and not horizontally, from the load terminals.
Output cable extending vertically down from the load terminals must be bent at two right angles thus forming an S-shape before passing through an exit port in the bottom of the drawout unit. Depending on the voltage class, output cable may be up to a few inches in diameter and relatively inflexible due to its construction. Consequently, the minimum bending radius of the cable may be large. Because of this large minimum bending radius of the cable, and because the output port through which the output cable passes is usually not directly below the load terminals, the cable must be bent at right angles twice to pass out of the drawout assembly. Bending the cable to form two right angles requires an appreciable amount of space more than a single right angle bend would require. Thus, the drawout assembly must be of a larger size than is really necessary to accommodate both right angle bends. Furthermore, as the number of output cables depending from the load terminals increases, an increasing amount of space is required at the bottom of the drawout to accommodate the cables.
SUMMARY OF THE INVENTION
In an exemplary embodiment of the invention, a drawout assembly is configured to confine an electrical motor control unit comprising a plurality of vertically arranged electrical devices. A load terminal is positioned on a bus brace having horizontally-oriented receptacles for receiving lugs which receive output cables. The horizontally-oriented receptacles allow the output cable to be bent only once at a right angle before passing vertically out of the bottom of the drawout assembly. The bus brace has disposed on it a plurality of these receptacles for receiving the lugs, which may or may not be aligned. The lugs are electrically secured within the receptacles to maintain electrical contact with line-connected bus straps positioned under the receptacles.
Attaching output cables to the load terminals in a horizontal configuration will enable the cables to be bent only once before they pass through the exit port. Use of only a single bend will thus allow the same stabs, bus straps, circuit interrupting device, distribution power load circuit, load terminals, and cable to be fit into a smaller drawout due to more efficient use of space. Use of a smaller drawout, while maintaining the same internal components, translates into a more manageable drawout
REFERENCES:
patent: 4700271 (1987-10-01), Lio et al.
patent: 5046173 (1991-09-01), Wall, Jr.
patent: 5343356 (1994-08-01), Hancock
patent: 5898566 (1999-04-01), Noschese et al.
patent: 5966295 (1999-10-01), Park
patent: 6034865 (2000-03-01), Roster et al.
Bernier Richard E.
Piper Charles W.
Soares Gilbert A.
Struble, Jr. John J.
Cantor & Colburn LLP
General Electric Company
Horton Carl B.
Thompson Gregory
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