Connecting device for control terminals in withdrawable type circuit breaker

The present invention relates to a connecting device for control terminals in a withdrawable type circuit breaker, and more particularly, a connecting device for control terminals in a withdrawable type circuit breaker, capable of automatically connecting or separating control power source terminals for controlling the circuit breaker upon pulling out or inserting a breaker main body.

CROSS-REFERENCE TO RELATED APPLICATION

Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of earlier filing date and right of priority to Korean Application No. 10-2016-0145353, filed on Nov. 2, 2016, the contents of which are all hereby incorporated by reference herein in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This specification relates to a connecting device for control terminals in a withdrawable type circuit breaker, and more particularly, a connecting device for control terminals in a withdrawable type circuit breaker, capable of automatically connecting or separating control power source terminals for controlling the circuit breaker upon pulling out or inserting a breaker main body.

2. Background of the Invention

In general, a circuit breaker is an electrical device that opens or closes a load in a transmission, a substation or an electrical circuit, or breaks a circuit when an accident such as a ground or short circuit occurs. Among these circuit breakers, an air circuit breaker is a circuit breaker using air as an arc-extinguishing medium and is mainly used for low voltage appliances.

The circuit breakers are classified into a fixed type which is fixed in the switchboard or other places, and a withdrawable type in which a breaker main body is installed in a cradle to be pushed in or pulled out of the cradle. The withdrawable type is widely used in terms of advantageous maintenance of the breaker main body.

Meanwhile, the circuit breaker is provided with control terminals for monitoring or controlling the circuit breaker. The control terminals of the withdrawable type circuit breaker are provided in the breaker main body and the cradle. When the breaker main body is pushed into the cradle, the control terminals may be connected to each other and a control signal can be transmitted accordingly.

The withdrawable type circuit breaker is located (disposed), according to relative positions of the breaker main body and the cradle, in three positions (states), namely, a disconnect position (state) in which a control power source is completely disconnected from the cradle, a test position (state) in which the breaker main body is inserted into the cradle by a predetermined distance (depth) such that the control (power source) terminals are connected so as to check a connected state of the circuit breaker, and a connect position (state) in which the breaker main body is completely pushed into the cradle and thus main circuit terminals are connected such that a current flows along a main circuit.

Here, the control terminals are disconnected from each other in the disconnect state and connected to each other in the test state and the connect state. That is, when the breaker main body is moved from the disconnect state to the test state, a cradle-side control terminal module is fixed and a main body-side control terminal module should be moved to be connected to the fixed cradle-side control terminal module. When the breaker main body is moved from the test state to the connect state, the cradle-side control terminal module and the main body-side control terminal module should be moved together with the breaker main body while being connected to each other. Also, a disconnection process is reverse to the connection process.

Hereinafter, description will be given of a prior art (Korean Patent Application No. 10-2016-0017463 ‘Connecting device for control terminals in withdrawable air circuit breaker’ that the inventor of the present application has applied as an invention proposed for allowing connection and movement of the control terminals to be automatically executed according to a moved position of a breaker main body.

FIGS. 1 to 3illustrate operation views of the connecting device for the control terminals in the withdrawable air circuit breaker according to the prior art, which illustrate a disconnect state, a test state and a connect state, respectively.

In the prior art, a connecting device for control terminals in a withdrawable air circuit breaker includes a fixed control terminal module230installed on the breaker main body200, a movable control terminal module130movably installed on the cradle100, and a locking device400. The locking device400operates in cooperation with a transfer unit.

The transfer unit includes a screw shaft310rotated by a handle (not illustrated), a rack320moving back and forth in response to the rotation of the screw shaft310, a pinion330engaged with the rack320, a link assembly340coupled to the pinion330, and a cam350coupled to the link assembly340.

When the breaker main body200is pushed into the cradle100and moves from the disconnect state to the test state (FIG. 1→FIG. 2), the rotation of the screw shaft310is transferred to the rack320, the pinion330, the link assembly340and the cam350and thus the cam350is rotated in a counterclockwise direction. The locking device400is restrained at a head portion of the cam350so as to lock the movable control terminal module130. In this instance, a locking part413formed at the upper end of the locking device400is in a state of restraining a support member132of the movable control terminal module130. Accordingly, the fixed control terminal module230of the breaker main body200is inserted into the movable control terminal module130and connected to a control circuit.

When the breaker main body200is continuously inserted into the cradle100from the test state to the connect state (FIG. 2→FIG. 3), the cam350is further rotated such that the head portion of the cam350pulls down the locking device400. Accordingly, the locked movable control terminal module130is released, and thus the control terminal modules130and230are moved up to the connect state while being connected to each other.

However, in the prior art, since the locking device400operates in cooperation with the transfer unit, it is dependent on the transfer unit. That is, the locking device400may be likely to be malfunctioned due to an error of the transfer unit, and a mechanism that operates in cooperation with the transfer unit should be designed. As a result, the construction of the locking device400becomes complicated and instability and inaccuracy may occur in the operation of the locking device400. Accordingly, there is a need for a locking device that independently operates without the cooperation with the transfer unit.

SUMMARY OF THE INVENTION

Therefore, to solve the aforementioned problems and other drawbacks, an aspect of the detailed description is to provide a connecting device for control terminals in a withdrawable circuit breaker, capable of connecting or disconnecting control power terminals for controlling the circuit breaker in an independent manner, without cooperation with a transfer unit, when a breaker main body is pushed in or pulled out.

To achieve these and other advantages and in accordance with the purpose of this specification, as embodied and broadly described herein, there is provided a connecting device for control terminals in a withdrawable type circuit breaker, the device including a cradle-side control terminal module horizontally installed on a cradle to be slidable thereon, a main body-side control terminal module provided on a breaker main body to be contactable with or separated from the cradle-side control terminal module, and a blocking unit restricting or allowing a motion of the cradle-side control terminal module, wherein the blocking unit may include a latch release plate fixed to a side surface of the breaker main body and provided with a contact surface on one surface thereof, the contact surface having a flat portion and an inclined portion, and a latch rotatably disposed on a side surface of the cradle and performing a sliding or rotational motion along the contact surface.

Here, the latch may include a restricting portion formed on one end thereof and brought into contact with the cradle-side control terminal module to restrict a movement of the cradle-side control terminal module, and a contact portion formed on another end thereof and moving along an upper surface of the contact surface.

The contact portion may be formed as a protrusion in a cylindrical shape, and the cradle may be provided with a latch operation hole in which the contact portion is inserted for movement.

The contact surface may include a first flat portion with which the contact portion is brought into contact while the breaker main body moves from a disconnect state to a test state, a first inclined portion with which the contact portion is brought into contact in the test state, and a second flat portion with which the contact portion is brought into contact while the breaker main body moves from the test state to a connect state.

Also, the device may further include a second inclined portion with which the contact portion is brought into contact in the connect state, and a third flat portion formed on a portion symmetrical to the first flat portion based on the second flat portion.

The first flat portion and the second flat portion may be formed at different height from each other.

The latch release plate may include a body portion installed at a predetermined distance from a side surface of the breaker main body and having the contact surface on one surface thereof, and coupling portions bent from both ends of the body portion and coupled to the side surface of the breaker main body.

The latch release plate may be integrally formed with a transport handle of the breaker main body.

The device may further include an elastic member having one end fixed to one side of the latch and another end fixed to a part of the cradle.

The elastic member may be a compression spring or a tension spring.

In a connecting device for control terminals in a withdrawable type circuit breaker according to one embodiment of the present invention, a cradle-side control terminal may be maintained in a locked state while a breaker main body moves from a disconnect position to a test position. This may result in a smooth connection of the control terminals. Also, the locked state of the cradle-side control terminal can be released while the breaker main body moves from the test position to a connect position. This may allow the control terminals in a connected state to each other to be moved into the cradle together.

Also, since the connecting device for the control terminals independently operates without cooperation with a transfer unit, a configuration of the device can be simplified and accuracy and stability of a connecting operation thereof can be improved. In addition, components of the device can be simplified.

DETAILED DESCRIPTION OF THE INVENTION

Description will now be given of preferred configurations, with reference to the accompanying drawings, which is to explain in detail enough that those skilled in the art to which the present invention belongs can easily practice the invention. It should not be construed to limit the technical scope and spirits of the present invention.

FIG. 4is a perspective view of a connecting device for control terminals in a withdrawable type circuit breaker according to an embodiment of the present invention, andFIGS. 5 to 7are perspective views of a cradle-side control terminal module, a latch release plate, and a latch which are employed in a connecting device for control terminals in a withdrawable circuit breaker in accordance with one embodiment of the present invention. Also,FIGS. 8 to 10are operation views of a connecting device for control terminals in a withdrawable circuit breaker in accordance with one embodiment of the present invention, which illustrate a disconnect state, a test state and a connect state, respectively. Hereinafter, each of the embodiments of the present invention will be described in detail with reference to the drawings.

A connecting device for control terminals in a withdrawable type circuit breaker according to an embodiment of the present invention includes a cradle-side control terminal module25horizontally installed on the cradle10to be slidable thereon, a main body-side control terminal module40provided on a breaker main body30to be connectable to or separated from the cradle-side control terminal module25, and a locking unit that restricts or allows (locks or unlocks) a motion of the cradle-side control terminal module25. The locking unit includes a latch release plate50fixed to a side surface of the breaker main body30and having a contact surface54formed on one surface thereof and provided with a flat portion and an inclined portion, and a latch60rotatably installed on a side surface of the cradle10and executing a sliding motion or a rotational motion along the contact surface54.

FIG. 4is a perspective view of the cradle10according to the embodiment of the present invention. A side portion is partially cut off to facilitate understanding of an internal structure.

The cradle10may be formed in a box-like shape with its front surface open to accommodate the breaker main body30. Slits12for installing the cradle-side control terminal module25to be slidable therealong are formed at both side surfaces of the cradle10. Each of the slits12is formed horizontally in a shape of a straight line. A spring hole22is formed at the rear of each slit12to install an elastic member70. The spring hole22may be formed to be inclined at a predetermined angle with respect to a perpendicular direction. A fixing protrusion23for fixing an upper end portion of the elastic member70may be formed on an upper end portion of the spring hole22. A latch operation hole24in which a part of the latch60is operably inserted is formed below the spring hole22. The latch operation hole24may be formed in an arcuate shape.

Cradle terminals11for connecting the cradle to a power source side circuit and a load side circuit are provided on a rear surface of the cradle10(FIG. 8). Discharge holes13for discharging gas coming out of an arc chute31of the breaker main body30is formed through an upper portion of the cradle10. Rails14are provided on inner side surfaces of the cradle10to receive the breaker main body30such that the breaker main body30is drawn out of or inserted into the cradle10. A transfer unit by which the breaker main body30mounted on the rails14is drawn out of or inserted into the cradle10is provided on side and lower portions of the cradle10.

Here, the transfer unit includes a screw shaft15provided on a lower portion of the cradle10in back and forth directions, and receiving a rotational force by a manual handle (not illustrated) or a gearing (not illustrated), racks16installed to be movable in back and forth directions of the cradle10in response to the rotation of the screw shaft15, a rotating shaft18rotated by pinions17engaged with the racks16, link assemblies18provided at both end portions of the rotating shaft18, cams20mounted on inner side surfaces of the cradle10and rotated by forces from the link assemblies19, and cam followers35provided on both side surfaces of the breaker main body30to be coupled to cam slots21formed at the respective cams20.

The cam slot21of each cam20serves to push or pull the cam follower35inserted into the cam slot21when the cam20rotates, such that the cam follower35moves horizontally. Here, the cam follower35may be configured as a roller for reducing friction.

The breaker main body30is provided therein with a switch mechanism, a contact portion, and an arc-extinguishing portion. The arc chute31as the arc extinguishing portion for extinguishing an arc is exposed at an upper portion of the breaker main body30. The main body-side control terminal module40, which can be coupled to the cradle-side control terminal module25, is installed on the upper portion of the breaker main body30. An ON button32for a closing operation and an OFF button33for an opening operation are provided on a front panel of the breaker main body30. An overcurrent relay34for transmitting a trip signal when an overcurrent is generated is installed on one side of the breaker main body30. Rollers36disposed on the rails14to be rollable are provided on both side surfaces of the breaker main body30.

The breaker main body30can be mounted on the rails14of the cradle10and moved inward by the transfer unit. In this instance, positions or states of the air circuit breaker are divided, according to a relative position of the breaker main body30within the cradle10, into three positions (states), namely, a disconnect position (state) (seeFIG. 8) at which a control power source is completely disconnected, a test position (state) (seeFIG. 9) at which the breaker main body30is moved rearward by a predetermined distance and thus the main body-side control terminal module40is connected to the cradle-side control terminal module25so as to check a connected state of the circuit breaker, and a connect position (state) (seeFIG. 10) at which the breaker main body30is completely inserted into the cradle10and thus a main body terminal (not illustrated) is connected to the cradle terminal11such that a current can flow along a main circuit.

Referring toFIGS. 4 and 5, the cradle-side control terminal module25includes a plurality of cradle-side connectors29, and a support plate26having a plurality of holes into which the cradle-side connectors29can be inserted.

The support plate26is provided with a perpendicular plate having the plurality of holes, an upper surface formed by bending an upper portion of the perpendicular plate, and support surfaces27formed by bending horizontally both lower end portions of the perpendicular plate. The cradle-side control terminal module25is slidably installed in a manner that the support surfaces27of the support plate26are inserted into the slits12formed at the side surfaces of the cradle10. That is, the cradle-side control terminal module25is movable back and forth along the slits12.

The main body-side control terminal module40includes a plurality of main body-side connectors41and a support base42on which the main body-side connectors41are installed. When the breaker main body30moves to the test position within the cradle10, the main body-side connectors41are inserted into the cradle-side connectors29to be connected to the control circuit.

Referring toFIGS. 4 and 7, the latch60is rotatably mounted on the side surface of the cradle10. The latch60may be formed of a ‘¬’ shaped plate. The latch60is provided with a shaft hole62that allows the latch60to be inserted into a latch shaft61which is provided below the slit12formed through the side surface of the cradle10. Of course, although not illustrated separately, according to embodiments, the latch shaft may be integrally formed with the latch60and the shaft hole may be formed through the side surface of the cradle10.

A restricting portion63for restricting the movement of the cradle-side control terminal module25with being brought into contact with the cradle-side control terminal module25is provided on a top of a front end portion of the latch60. The restricting portion63may be formed as a recess. Therefore, the restricting portion63comes into contact with the rear surface of the support surface27of the cradle-side control terminal module25, thereby preventing the cradle-side control terminal module25from moving to a rear side.

A protruding portion64protrudes from a top of a rear end portion of the latch60to fix a lower end portion of the elastic member70. The protruding portion64may protrude inwardly to be partially inserted into the spring hole22formed through the side surface of the cradle10.

A contact portion66protruding inward in a cylindrical shape is provided on a lower end portion65of the latch60(a portion extending downward from one end of the latch60). The contact portion66is inserted into the latch operation hole24of the cradle10so as to come in contact with the latch release plate50inside the side surface of the cradle10, thereby rotating the latch60.

Referring toFIGS. 4 and 6A, the latch release plate50is fixed to the side surface of the circuit breaker body30. The latch release plate50includes a body portion51disposed at a predetermined distance from the side surface of the circuit breaker body30, and coupling portions52formed at both ends of the body portion51in a bent manner and coupled to the side surface of the circuit breaker body30.

A contact surface54is formed in a stepped shape on an upper surface of the body portion51of the latch release plate50. The contact surface54includes a first flat portion55which is a surface with which the contact portion66is slidably brought into contact while the breaker body30moves from the disconnect position to the test position, a first inclined portion56which is a surface with which the contact portion66is brought into contact at the test position, and a second flat portion57which is a surface with which the contact portion66is slidably brought into contact while the breaker main body30moves from the test position to the connect position.

Referring toFIG. 6B, the latch release plate50may further include a second inclined portion58which is provided on the contact surface54of the previous embodiment (FIG. 6A) and with which the contact portion66is brought into contact at the test position. Also, a third flat portion59may be formed at a portion symmetrical to the first flat portion55based on the second flat portion57. Here, the first inclined portion56and the second inclined portion56may be curved.

The latch release plate50may be formed symmetrically. That is, the first flat portion55may be formed at the same height as the third flat portion59, and the first inclined portion56may be formed as an inclined surface that is symmetrical with the second inclined portion58. This is for the latches60to be shared and used when the latches60are installed on both side surfaces of the breaker main body30.

Referring toFIG. 11, the second flat portion57is formed higher than the first flat portion55by a predetermined height. Here, the height difference between the first flat portion55and the second flat portion57is referred to as ‘h’. h should be greater than the height of the restricting portion63.

It is assumed that a portion where the contact portion66comes in contact with the contact surface54at the disconnect position is referred to as ‘A,’ a portion where the contact portion66comes in contact with the contact surface54at the test position is referred to as ‘B’ and a portion where the contact portion66comes in contact with the contact surface54at the connect position is referred to as ‘C.’ A located on the first flat portion55, B is on the first inclined portion56, and C is on the second inclined portion58. In this instance, if it is assumed that a distance between A and B (‘A-B’) is d1 and a distance of ‘A-C’ is d, d1 corresponds to a moving distance between the disconnect position and the test position, and d corresponds to a moving distance between the disconnect position and the connect position. The moving distance of the breaker main body30is shown based on (from) the rear end portion of the cover at the upper portion of the main body-side control terminal module40of the breaker main body30. Namely, if L1 denotes a distance moved from the disconnect position to the test position and L denotes a distance moved from the disconnect position to the connect position, L=d and L1=d1.

According to an embodiment, the latch release plate50may be integrally formed with a transport handle of the breaker main body30. As a result, additional objects can be achieved without increasing the number of components.

The elastic member70is provided to buffer the movement of the latch60to smoothly move the latch60and assist the latch60to return to its original position when the latch60is pulled out. An upper end portion of the elastic member70is fixed to the fixing protrusion23of the spring hole22and a lower end portion of the elastic member70is fixed to the protruding portion64of the latch60. The elastic member70may be configured as a compression spring or a tension spring. In this embodiment, the elastic member70is configured as a compression coil spring. Since the latch60receives force applied downward by the elastic member70, the latch60can be slid in place on the flat portion and smoothly rotate along the inclined surface on the inclined portion during the movement of the latch release plate50, whereas fast returning to its original position during the return.

Hereinafter, an operation of the connecting device for the control terminals in the withdrawable type circuit breaker according to the embodiment of the present invention will be described with reference toFIGS. 8 to 11.

FIG. 8illustrates that the breaker main body30is inserted into the cradle10and is located at the disconnect position. In this instance, the restricting portion63of the latch60fixes the support surface27of the cradle-side control terminal module25to restrict the movement of the cradle-side control terminal module25. The main body-side control terminal module40is in contact with the cradle-side control terminal module25. The contact portion66of the latch60is also located at a point A (seeFIG. 11) of the first flat portion55of the latch release plate50. Here, the cam follower35of the breaker main body30is hooked to an entrance of the cam slot21. When the user rotates the screw shaft15in an inserting direction by a manual handle or a gearing, the rotational force causes the cam20to rotate counterclockwise through the respective components of the transfer unit, and accordingly the cam follower35is pulled by the cam slot21such that the breaker main body30moves rearward.

As the breaker body30moves, the latch release plate50also moves together and the contact portion66executes a sliding or curving motion along the contact surface54.

First, when the breaker main body30is moved from the disconnect position to the test position (FIG. 8→FIG. 9), the contact portion66is slid on the first flat portion55of the contact surface54and brought into contact with the first inclined portion56. During this process, since the cradle-side control terminal module25is in a stopped state with being restricted by the latch60, the main body-side control terminal module40is inserted into the cradle-side control terminal module25and connected to the control circuit.

FIG. 9illustrates a state in which the breaker main body30is placed at the test position. The contact portion66is placed at a point B of the contact surface54(seeFIG. 11) and the main body-side control terminal module40is in a state of being coupled to the cradle-side control terminal module25.

When the user further rotates the screw shaft15at the test position, the breaker main body30moves rearward beyond the test position. The contact portion66passes the first inclined portion56to arrive at the second flat portion57, and the latch60rotates counterclockwise centering on the latch shaft61to release the locked (restricted) restricting portion63. Accordingly, the control terminal modules25and40can move rearward together with the breaker main body30. In this instance, since the latch60is subjected to the force applied by the elastic member70, the rotational motion is performed not suddenly but smoothly. (The rotational motion of the latch60may be completed at the test position as illustrated inFIG. 9. That is, the rotational motion of the latch60may be executed between before and after approaching the test position.)

FIG. 10illustrates a state in which the breaker main body30is located at the connect position. The contact portion66is placed at a point C of the contact surface54(seeFIG. 11), and the support surface27of the cradle-side control terminal module25moves to a rear portion of the slit21by passing the upper surface of the latch60by a predetermined distance.

The connecting device for the control terminals in the withdrawable type circuit breaker according to the embodiment of the present invention operates according to the relative positions of the breaker main body30and the cradle10without cooperation with the transfer unit. Therefore, it can obtain stability and accuracy of the operation. Further, the components thereof can be simplified.

When withdrawing the breaker main body30, it operates in the opposite direction to that at the time of insertion. When the user rotates the screw shaft15in a withdrawing direction, the rotational force causes the cam20to rotate clockwise through the respective components of the transfer unit, and accordingly the cam slot21pushes the cam follower35so that the breaker main body30is moved forward.

First, at the connect position ofFIG. 10, the contact portion66is located at a point C of the contact surface54and the main body-side control terminal module40is connected to the cradle-side control terminal module25. When the breaker main body30is pulled out and moved to the test position, the contact portion66is slid along the second flat portion57. In this instance, the control terminal modules25and40are moved forward together with the breaker main body30.

When reaching the test position as illustrated inFIG. 9, the contact portion66is placed at the point B of the contact surface54, and the restricting portion63is brought into contact with the rear end of the support surface27.

When the breaker main body30is further pulled out, the support surface27is inserted into the restricting portion63of the latch60, and the cradle-side control terminal module25is in a stopped state by being blocked at the front end portion of the slit12. Accordingly, since the cradle-side control terminal module25is fixed, the main body-side control terminal module40is separated from the cradle-side control terminal module25.

When the breaker main body30reaches the disconnect position as illustrated inFIG. 8, the main body-side control terminal module40is completely separated from the cradle-side control terminal module25, and the contact portion66is placed at the point A of the contact surface54.

FIG. 12is a partial side view of a connecting device for control terminals in a withdrawable type circuit breaker according to another embodiment of the present invention.

In this embodiment, a contact surface54ais formed on a lower surface of a latch release plate50a. A latch60ahas a lower end portion65awhich extends from one end thereof in a bent manner. The lower end portion65aextends longer than a lower end portion of the latch in the previous embodiment. A contact portion66aof the latch60acontacts a contact surface54aat a lower portion of the contact surface54a. An elastic member70amay be configured as a tension spring. In addition, the latch60ais provided with a hole for fixing one end of the tension spring, other than the protruding portion as in the previous embodiment. That is, the elastic member70acan be fixed to holes formed in the cradle10and a part of the latch60a, respectively.

Since the operation in this embodiment is similar to that in the previous embodiment, only the difference will be described. One end of the latch60areceives force directed upward by the elastic member70and thus the latch60areceives force to rotate counterclockwise. Therefore, while the breaker main body30passes the test position, the contact portion66apasses along the first inclined portion56a, and the latch60athus receives force from the elastic member70awhich is restored upward. Accordingly, the latch60arotates counterclockwise.

The present invention has been explained with reference to the embodiments which are merely exemplary. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.