Electricity: electrical systems and devices – Electrostatic capacitors – Fixed capacitor
Patent
1988-03-07
1989-08-22
Scott, J. R.
Electricity: electrical systems and devices
Electrostatic capacitors
Fixed capacitor
200 50AA, 361339, 361343, H02B 1112
Patent
active
048601616
DESCRIPTION:
BRIEF SUMMARY
FIELD OF ART
The present invention relates to an enclosed switchboard such as a motor control center and the like.
BACKGROUND OF THE INVENTION
For enclosed switchboards such as motor control centers, in general, a box-like panel frame is divided by shelves into a plural number of compartments, each compartment accommodating a pullout control unit. The control unit is of such a circuit configuration that various pieces of control equipment including a circuit breaker, an electromagnetic switch, and a control relay are placed on a common frame to provide a desired control function. The main circuit, or occasionally the control circuit thereof is so constructed as to automatically connect to and disconnect from the corresponding circuit on the panel frame side by a put-in and pull-out operation.
Contacts are so arranged on the rear of the control unit that putting in the control unit brings a power contact into connection with a bus bar (generally a vertical bus bar) arranged on the panel frame of the switchboard, through which power is supplied to each on-board piece of equipment. This also brings a load contact into connection with the load side terminal, thereby supplying the load side with power switched on and off by way of the control unit.
The enclosed switchboard provided with such a drawer type control unit is so designed that the front door of the panel frame can be closed only with the units in their retracted positions. Meanwhile, in the test and disconnected positions with the contacts drawn out of the bus bars the control units are projected from the front of the panel frame, preventing closing of the door.
In the conventional switchboard described above the door can not be closed in the disconnected and test positions but only in the connected position, necessitating that the door be left open while checking the interior, in the testing position or the disconnected position. However, leaving the door open impairs the enclosed function of the switchboard, allowing for electric shock and other dangers due to the emission of arcs and substances out of the switchboard in case of accidents. It may also block the passage and hamper operators from going through, sometimes causing injuries or damage due to accidental bumping.
For these reasons, when any control unit need not be placed in the connected position for a long time, it is removed and kept separately so as to allow the door of the switchboard to be closed to maintain its enclosed function and keep the passage open.
Taking into account the above background, the purpose of the present invention is to provide an enclosed switchboard in which the door can be closed in the disconnected and test positions of the control units thereof as well as in its connected position.
SUMMARY OF THE INVENTION
In order to achieve this purpose, the enclosed switchboard of the present invention has an equipment mounting unit frame set retractably in a shelf of a panel frame, a contact frame fitted with a power contact connecting and disconnecting with a bus bar wired in the panel frame and a load contact connecting and disconnecting with a load side terminal, the contact frame being mounted movably in the connecting and disconnecting direction of the unit frame, a lever linking mechanism built in the unit frame and converting the turning motion of an operating handle situated at the front of the unit frame to a traveling motion toward and from the unit frame, the linking mechanism being provided with a mechanism limiting the corresponding position of the contact mounting frame when the contacts are in the respective positions connected to and disconnected from the bus bar and the load side terminal, the limiting mechanism being equipped with a different mechanism for releasing a limited state to provide an operable state through a limit releasing operation prior to operating the handle in each limited position as well as releasing the operable state by the handle in each limited position to return back to the limited state, and positions and dimensions set i
REFERENCES:
patent: 3663773 (1972-05-01), Powell
patent: 4051335 (1977-09-01), Ericson et al.
patent: 4112269 (1978-09-01), Nelson et al.
patent: 4317160 (1982-02-01), Tillson et al.
Maki Kazuyoshi
Otsubo Masayuki
Uchida Shizutaka
Scott J. R.
Togami Electric Mfg. Co.
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