Interlock mechanism for a distribution cabinet

The present disclosure relates to an interlock mechanism for automatically locking and unlocking a lock system of an electrical cabinet based on the state of bolted pressure contact switches housed within the electrical cabinet.

TECHNICAL FIELD

The present disclosure relates to electric switch assemblies housed within high voltage switchgear enclosures. More specifically, the present disclosure relates to a locking mechanism for use with high voltage switchgear enclosures.

BACKGROUND

Electrical devices, such as bolted pressure contact switches, can be enclosed in electrical cabinets that have an operating handle located on a door or cover of the electrical cabinet. A device operating mechanism is typically located inside the electrical cabinet for switching the contact switches between ON and OFF positions. It is known that in certain situations the door of the electrical cabinet can be opened while the contact switches are closed or in the ON position.

Improvements are needed to enhance safety features for electrical devices activated within an electrical cabinet.

SUMMARY

Aspects of the present disclosure relate to an interlock mechanism for automatically locking and unlocking an access door of an electrical cabinet based on the state of bolted pressure contact switches housed within the electrical cabinet.

Due to the action of the interlock mechanism, the electrical cabinet may be provided with safety features whereby the state of the switch itself either prohibits or permits access inside the electrical cabinet. That is, the access door of the electrical cabinet can be unlocked or locked due to the action of interlock mechanism according to the present disclosure. The door can be automatically locked when the contact switches are moved to their closed state and the door can be automatically unlocked when the contact switches are moved to their open state.

The interlock mechanism can be mounted within the electrical cabinet and be connected to a switch operating mechanism so as to cooperate therewith and move between positions corresponding respectively to the closed and open positions of the contact switches.

Aspects of the present disclosure relate to an automatic interlock assembly for use within an electrical cabinet including an access door. The electrical cabinet can include contact switches and a switch actuator mechanism operatively interconnected with the contact switches to shift the contact switches between OPEN and CLOSED conditions. The automatic interlock assembly can include a lock system mounted in the electrical housing. The lock system can include a slider rod and a linkage. The slider rod can have a first end and an opposite second end. The slider rod can be movable between an extended position and a retracted position.

The automatic interlock assembly can include a multi-position arm mounted within the electrical cabinet. The multi-position arm can be in releasable contact with the linkage of the lock system. The multi-position arm can be operable between a first position and a second position that respectively correspond with the OPEN and CLOSED conditions of the contact switches.

The automatic interlock assembly can include a door assembly mounted on the access door. The door assembly can include a door bracket and a hook bracket mounted to the door bracket. The hook bracket can be received within an opening defined in the slider rod when the access door is closed.

When the multi-position arm moves with the switch actuator mechanism from the CLOSED condition to the OPEN condition, the multi-position arm is in the first position to make contact with the linkage. The multi-position arm pushes the linkage upward and holds the slider rod in the extended position. The hook bracket is configured to move without obstruction within the opening of the slider rod such that the lock system remains unlocked.

When the multi-position arm moves with the switch actuator mechanism from the OPEN condition to the CLOSED condition, the slider rod and the linkage follow the multi-position arm downwardly as the multi-position arm moves to the second position. The multi-position arm separates from the linkage to permit the slider rod to linearly move to the retracted position. The hook bracket can be restricted by a leg of the slider rod from moving out of the opening such that the lock system locks.

These and other features and advantages will be apparent from a reading of the following detailed description and a review of the associated drawings. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the broad concepts upon which the embodiments disclosed herein are based.

DETAILED DESCRIPTION

Electrical switches are often used as a main disconnect for commercial and industrial applications. Electrical switches are typically housed within electrical cabinets or boxes. Traditionally, an external handle is mounted on the electrical cabinets. The handle can be connected to an actuator mechanism within the cabinet such that when the handle is pivoted by a user, mechanical energy to the actuator mechanism actuates the electrical switches to safely make or break circuit current through the switches to ensure electrical connection and disconnection of the circuit.

FIG.1the shows an electrical cabinet10. While the example embodiment discussed herein is with reference to the electrical cabinet10, other types of closures (e.g., electrical boxes, junction boxes, control panels, lighting panels, motor control centers, switchgear housings, relay cabinets) or any other type of closure (e.g., a flame-proof enclosure) may be used. An access door12can be hingedly connected to a door frame14by one or more hinges16. The access door12can swing freely on the hinges16when the door12is unlocked. The access door12incorporates a door handle18shown fixed on an outer surface20of the access door12. The electrical cabinet10may further incorporate a trip device22in the form of a push button, rotational button or key.

Referring toFIG.2, the electrical cabinet10includes an electrical switch assembly24known as a bolted pressure switch assembly. As shown, the electrical switch assembly24includes two sets of electrical contacts26(e.g., contact switches), although alternatives are possible. In certain examples, the electrical switch assembly24may include three sets of electrical contacts. The electrical switch assembly24is configured to pivot from an OPEN condition where there is no electrical contact to a CLOSED condition where there is electrical contact. An example switch assembly is disclosed in U.S. Pat. No. 10,319,544, which is incorporated herein by reference in its entirety.

A switch actuator mechanism28can be mounted within the electrical cabinet10. The switch actuator mechanism28can be operatively interconnected with the electrical switch assembly24. The switch actuator mechanism28can be manually operated by the door handle18for shifting the electrical switch assembly24between the OPEN (e.g., OFF position) and CLOSED (e.g., ON position) conditions. An example actuator mechanism is disclosed in U.S. Pat. No. 10,319,544, which is incorporated herein by reference in its entirety.

The switch actuator mechanism28can include an actuator30, a cam assembly32and a pair of springs34. The cam assembly32acts between the actuator30and the springs34to store and release energy in the springs34. During operation, the actuator30can be rotated manually using the door handle18from a first position to a second position, although alternatives are possible. In certain examples, the actuator30may be moved automatically.

When the actuator30is rotated toward the second position, the cam assembly32first compresses one of the springs34, and then latches the compressed spring34in a stressed condition. The actuator30is next rotated back to the first position such that the compressed spring34remains latched, and the cam assembly32compresses the other spring34to a stressed condition. However, the cam assembly32does not latch the other spring34in the compressed condition but rather releases the other spring34to snap back from the compressed condition. The return movement of the other spring34drives the cam assembly32to shift the electrical switch assembly24from the OPEN condition to the CLOSED condition under the bias of the released spring34.

The trip device22can be configured for releasing the latched spring34, which then drives the cam assembly32to shift the electrical switch assembly24back to the OPEN condition in a known manner.

In order to comply with operating standards for high voltage equipment, it is required to lock the access door of electrical cabinets while current is running. That is, when bolted pressure contact switches become electrically energized with live voltages, a locking feature is required to ensure personnel safety. In prior systems, the electrical cabinet10would be provided with a lockout bar extending across a front of the access door12to indicate when the access door12is locked to prevent personnel from opening the access door12. However, access to the electrical cabinet may still be possible by manually moving the lockout bar.

As noted above, the door handle18may serve as an effective means for locking the access door12since the door handle18may be in a horizontal position when the switch is closed to prohibit access from outside the access door12. However, in certain examples, the door handle18may be removable and no longer prohibit access to the electrical cabinet10. This situation may create problems for the customer because the electrical state of the contact switch may not be clear. In other examples, the door handle18may be in the same position as initially and thus no indication of the ON or OFF position is provided or any restriction of access by the door handle18.

An automatic interlock assembly in accordance with the principles of the present disclosure is designed to solve the problem described above to ensure that if electrical switches are in an ON condition or closed position, no one can accidently open a door to an electrical box. The automatic interlock assembly allows the door to automatically lock or unlock with the change of state of the electrical switches.

Referring toFIGS.3-4, the electrical cabinet10has an automatic interlock assembly36(seeFIG.2). The automatic interlock assembly36can include a lock system38that is movable between a locked position and an unlocked position. The lock system38includes a slider rod40and a linkage42. The slider rod40has a first end44and an opposite second end46. The slider rod40can be movable between an extended position (e.g., upper or raised position)(seeFIG.3) and a retracted position (e.g., lower position)(seeFIG.4) that respectively correspond with the locked and unlocked positions of the lock system38.

The slider rod40can have a L-shaped transverse cross-section that has a first flat leg102that defines an opening48(e.g., cutout) and a second flat leg103that projects from the first flat leg102at a right angle. As the lock system38is moved between locked and unlocked positions, the slider rod40can slidably move inside L-shaped openings50(seeFIG.12) defined by first and second slider brackets52,54between the extended and retracted positions. The first and second slider brackets52,54can be mounted inside the electrical cabinet10by fasteners56. The slider rod40can be movable in a linear direction between the extended position and the retracted position.

Turning toFIGS.13-16, the linkage42of the lock system38can be connected to the slider rod40at the second end46for driving the slider rod40between its extended and retracted positions. The linkage42can be pivotally connected via a pivot structure58(e.g., mechanical fastener, stud, linear member, pin, bolt, etc.) to support brackets60that are fixed to a side of the frame14of the electrical cabinet10and are fixed to ground. The pivot structure58can include pins105that are secured in place by clips107. The linkage42can also be connected to the slider rod40via a fastener structure111that also includes pins105and clips107. The support brackets60can each define a slot62for receiving the pins105. The pins58can slidably move within the slots62to pivot the linkage42relative to the support brackets60and thus move the slider rod40linearly between its extended and retracted positions. The linkage42can also be fixed to an interlock block64(e.g., contact member) via pins105. The interlock block64has a contact surface66.

In certain examples, the contact surface66can extend in a plane P (seeFIG.6) that is not parallel with the slider rod40of the lock system38. In certain examples, the interlock block64and the slider rod40are connected together at an angle of less than 90 degrees, although alternatives are possible.

Turning toFIGS.5-7, the automatic interlock assembly36can include a multi-position arm68(e.g., movable element) that can be pivotally interconnected with the cam assembly32of the switch actuator mechanism28via the actuator30. As such, the multi-position arm68can be operably linked to the door handle18for manual operation of the electrical switch assembly24. That is, the multi-position arm68can be movable pivotally about a pivot axis70(seeFIG.2) of the actuator30between the OPEN (seeFIG.5) and CLOSED conditions (seeFIG.6) via the door handle18. The multi-position arm being operable between a first position and a second position that respectively correspond with the OPEN and CLOSED conditions of the electrical contacts26.

During operation, the multi-position arm68can be in releasable contact with the linkage42of the lock system38for automatically operating the lock system38while controlling the electrical switch assembly24. That is, the multi-position arm68may directly contact the contact surface66of the interlock block64to hold the slider rod40in the extended position when the electrical switch assembly24is in the OPEN condition. The multi-position arm68is configured to slidably move the linkage42along the slots62of the support brackets60as the multi-position arm68rotates about the pivot axis70between the OPEN and CLOSED conditions. That is, the multi-position arm68can separate from the contact surface66of the interlock block64as it moves with the switch actuator mechanism28from the OPEN condition to the CLOSED condition. When the multi-position arm68moves with the switch actuator mechanism28from the CLOSED condition to the OPEN condition, the multi-position arm68makes contact with the contact surface66and pushes the linkage42up along the slots62to slide the slider rod40up and holds the slider rod40in the extended position. When the multi-position arm68moves with the switch actuator mechanism28from the OPEN condition to the CLOSED condition, the slider rod40and the linkage42follow the multi-position arm68downwardly via gravity until the linkage42is stopped by the bottom of the slot62in which the multi-position arm68then separates from the contact surface66as it continues movement toward the CLOSED condition ofFIG.6. In certain examples, the slider rod40may be spring loaded for applications requiring horizontal directional movement between the extended and retracted positions.

Referring toFIGS.8-12, the automatic interlock assembly36can further include a door assembly72fixed to an inner surface74of the access door12via fasteners80. The door assembly72can include a door bracket76and a hook bracket78mounted on the door bracket76. The hook bracket78can include a flange member82that defines a slot84and an extension member86extending from the flange member82.

The flange member82can have a first side88a(seeFIG.12) and a second side88b(seeFIG.12) that is parallel to the first side88a. The flange member82can also include a third side90aand a fourth side90b. The third and fourth sides can be perpendicular to the first and second sides88a,88b. The fourth side90bof the flange member82can define the slot84. The extension member86can be angled relative to the second and fourth sides88b,90b. In certain examples, the extension member86can be positioned adjacent to the slot84. The flange member82includes a hook portion83that defines a portion of the slot84and from which the extension member86projects.

The hook bracket78can be spring loaded by a spring member92that has a first end94attached to the door bracket76via an opening96and a second end98that is attached to the flange member82of the hook bracket78via an opening100defined therein. The hook bracket78can pivot about a pivot axis79that extends longitudinally through a latch override actuator106(seeFIG.12). The spring member92biases the hook bracket78to a position about the pivot axis79in which the first and second sides88a,88bof the flange member82are generally horizontal. The extension member86projects upwardly from a top side81of the flange member82. The slot84extends into the flange member82and has an open end at the fourth side90band a closed end at an intermediate location between the third and fourth sides90a,90b.

When the access door12is closed as shown inFIG.10, the hook bracket78can interface with the slider rod40. Upon closing the unlocked access door12, electrical switch assembly24is in the OPEN condition and the slider rod40is in the extended position. With the slider rod40in the extended position, the hook bracket78can be received within the opening48of the slider rod40when the access door12is shut. Once the door is shut, the electrical switch assembly24can be shifted to the CLOSED condition. Upon shifting the electrical switch assembly24to the CLOSED condition, the slider rod40moves from the extended position to the retracted position such that the hook bracket78is positioned at a top end of the opening48of the slider rod40and the first flat leg102of the slider rod40is received into the slot84of the hook bracket78to lock the access door12. That is, the hook portion83of the hook bracket78is configured to interfere with the first flat leg102of the slider rod40to lock the access door12. If personnel attempt to open the access door12while the electrical switch assembly24is in the CLOSED condition, the hook portion83is blocked by the first flat leg102such that the hook bracket78cannot be removed from the opening48of the slider rod40, which prohibits personnel from opening the access door12.

The trip device22can be activated to switch the electrical switch assembly24to the OPEN condition, which actuates the linkage42for moving the slider rod40to the extended position. As this occurs, the blocking portion of the first flat leg102of the slider rod40raises such that it is no longer obstructing the extension member86of the hook bracket78to allow the hook bracket78to freely move out of the opening48of the slider rod40for opening the access door12.

There are circumstances in which authorized personnel (i.e., maintenance, etc.) may need to have access to the electrical equipment within the electrical cabinet10while electric current is running. In such cases, the access door12may be opened while not disconnecting the load by using a defeat mechanism. The defeat mechanism may include a separate tool that allows authorized personnel to defeat and unlock the access door12such that a power shut down can be avoided.

Referring toFIG.12, the door bracket76defines a hole104through which the latch override actuator106(e.g., a rotatable shaft) passes in which the latch override actuator106can be rotated about the pivot axis79. The latch override actuator106can have a first end108that is fixed to the hook bracket78and a second end110that includes a socket head112with a recess114shaped to receive a tool (not shown). Preferably, the tool and socket have a unique shape so as to provide a key function that allows only authorized personnel to open the lock system via the override actuator106. The latch override actuator106can be rotated about the axis79to adjust the position of the hook bracket78about the axis79against the bias of the spring member92. For example, the latch override actuator106can rotate the extension member86about the pivot axis to move the extension member86from a first orientation (e.g., a horizontal orientation) to a second orientation (e.g., an orientation angled relative to horizontal) in which the hook portion83is moved away from the blocking portion of the first flat leg102into alignment with the opening48of the slider rod40to allow the access door12to be opened. That is, the latch override actuator106can be rotated to rotate the hook bracket78within the opening48of the slider rod40which moves the extension member86away from the first flat leg102thereby defeating the automatic interlock assembly36.

Another aspect of the present disclosure relates to a method of operating an automatic interlock assembly of an electrical cabinet. The electrical cabinet can have an access door and electric switches disposed in the electrical cabinet and a cam assembly interconnected with the electrical switches for imparting operating movement thereto. The method can include the following steps: 1) providing a lock system that includes a slider rod and an interlock block connected to the slider rod; 2) providing a door assembly that includes a door bracket and a hook bracket attached to the door bracket; 3) providing a multi-position arm interconnected with the cam assembly; 4) moving the cam assembly and the multi-position arm to a first position such that the electric switches are OPEN and the slider rod is held in an extended position by engagement of the multi-position arm with the interlock block, and where the hook bracket is movable relative to the slider rod; and 5) moving the cam assembly and the multi-position arm to a second position such that the multi-position arm disengages the interlock block and the slider rod automatically moves from the extended position to a retracted position and the electric switches are CLOSED, and where movement of the hook bracket is restricted by the slider rod.