US 4,073,000 AGranted

Electrical interlock apparatus for electrical equipment

AssigneeS&C Electric Company

InventorRichard E. Krejsa

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Abstract

An interlock switch arrangement is used to disconnect the low voltage connections of electrical components such as transformers and the like in metal-enclosed switchgear. An electrical switch is mounted within a switch housing positioned and mounted adjacent to the access opening of the metal enclosure of the switchgear. A key projection or finger is mounted on a door overlying the access opening to the enclosure and positioned to enter an opening in the switch housing when the door is closed and to actuate the switch so that an electrical circuit is completed for electrical components within the enclosure. When the door is opened, the key projection disengages the switch causing the switch to open thereby electrically disconnecting the components so that a serviceman can perform maintenance with improved security against electrical shock. Typically, the invention is used on metal-enclosed switchgear having a double-door arrangement, i.e., an inner screen door and a outer solid door, and the projection is mounted on the inner screen door so that once the screen door is opened, certain of the electrical components are disconnected. However, when only visual inspection is desired, the outer door only may be opened so that the components can be observed through the inner screen door without the necessity of disconnecting the electrical components.

Claims3

Dependent claims

In metal-enclosed high voltage switchgear including a hollow metal enclosure having an access opening in a side thereof, a hinged door overlying the access opening for preventing access to the interior of the enclosure when closed, a hinged screen door overlying the access opening between the access opening and the hinged door for preventing access to the interior of the enclosure when closed but allowing access to the interior of the enclosure when opened, and electrical components within the interior of the enclosure having a source of electrical energy connected thereto;

an improvement comprising:
a switch housing mounted within the enclosure adjacent the access opening, said switch housing having a key opening formed through a front surface of said switch housing facing the access opening;
an electrical switch means mounted within said housing connected between the source of electrical energy and the electrical components for electrically connecting the components when closed and electrically disconnecting the components when opened;
an operating means positioned adjacent said key opening for closing said switch means when engaged and opening said switch means when disengaged;
a key projection mounted on the screen door positioned to project through said key opening and thereby align the screen door so that said key projection will engage said operating means when the screen door is closed over the access opening and disengage said operating means so that the source of electrical energy to the components is disconnected when the screen door is opened.

2 more elements

Dependencies are inferred from the claim text.