Electric power distribution panelboards and switchboards are currently available which accept circuit breakers and electric switches by means of a plug-on connection to the bus bars arranged therein. U.S. Pat. No. 4,744,003 describes one such panelboard arrangement. When electric switches or circuit breakers are to be installed on-site within such an operating panelboard, the electric power to the panelboard must be temporarily discontinued and the panelboard disassembled before such electric switch or circuit breaker can be installed. Where modification must be made to the panelboard interior in order to accept the electric switch or circuit breaker, some time is required before the power can be turned ON. This disruption in electric power within an industrial environment could cause scheduling problems both with respect to the related equipment as well as to operating personnel. To provide adequate electrical isolation between the different phases of a multi-phase panelboard or switchboard assembly, the bus conductors that transfer operating power from the electrical distribution circuits to the various switches connected with the panelboards and switchboards, large bus conductors are supported within the panelboard and switchboard interiors and heavy plates of insulative material are used to both support and electrically isolate the bus conductors. When the panelboards and switchboards are operated at near capacity levels, the heavy insulative plates thermally insulate the bus conductors and interfere with the convection air flow. Since the panelboard and switchboard enclosures are required to be closed in accordance with electrical industries standards, the temperature within the enclosures can rise substantially above ambient resulting in eventual damage to the panelboard components.
In accordance with the state-of-the-art panelboard and switchboard enclosures, a wide variety of electric switch designs are inventoried in order to meet the ampere requirements of varied electrical distribution circuits. The increased ampere-rated electric switches require larger components in order to accommodate the higher ampacity and to prevent the electric switches from overheating during long term steady state operating conditions.
It would be economically advantageous, to provide a single electric switch design that can operate over a wide range of ampere ratings and thereby eliminate the large inventory requirement of several electric switches of various component sizes. It would be further advantageous, to control the thermal environment within the panelboard and switchboard enclosure to safely and economically operate the switches at reduced operating temperatures.
U.S. Pat. No. 4,752,233, which Patent is incorporated herein for reference purposes, describes an adapter module for interfacing between an electric switch or circuit breaker and a panelboard or switchboard housing. The adapter module contains two compartments which allow two such circuit breakers, electric switches or a combination thereof to be plugged onto the panelboard or switchboard bus bars at one time. The adapter module also allows one electric switch or circuit breaker to be connected within one compartment while reserving the other compartment for add-on capability after the adapter is installed within the panelboard-switchboard enclosure.
U.S. Pat. Nos. 4,675,481; 4,785,145; 4,778,959; 4,778,961 each describe various electric switch configurations that can be received within the adapter module during factory or on-site installation. Since the components of each of the above described electric switches can be automatically assembled to reduce assembly costs, it would be further economically advantageous to assemble such switches in a panelboard or switchboard enclosure without incurring additional labor and component costs.
Further, when an electric switch or circuit breaker is required to be added to existing panelboard and switchboard enclosures, it would be economically advantageous to obtain such electric switch or circuit breaker in the form of a kit that can be quickly assembled within the panelboard and switchboard enclosure without having to completely disassemble the associated panelboard and switchboard housing.
One purpose of this invention accordingly is to provide a panelboard-switchboard housing that easily and quickly accepts multiple electric switch-circuit breaker enclosures without requiring long-time equipment shut-down. A further purpose of this invention is to provide an electric switch or circuit breaker modular enclosure that allow additional electric switches and circuit breakers to be field-installed at a minimum expense of time and labor.
An additional purpose of this invention is to provide a panelboard-switchboard housing that is designed to control the temperature rise of the bus conductors, electric switches and circuit breakers mounted within the housing.