Patent Description:
An air circuit breaker (ACB) device is installed at a low voltage distribution line and breaks a circuit in an arc extinguishing manner in an event of abnormal current such as overcurrent, short circuit or ground fault.

The air circuit breaker may be classified into a fixed type and an extendable type. The fixed air circuit breaker is fixed to a body without separate fixing means. The extendable air circuit breaker is coupled to a cradle and is connected to a main circuit, and is removable from the cradle for inspection or maintenance.

A plurality of terminals connected to the main circuit are arranged on the cradle coupled to the extendable air circuit breaker. When the extendable air circuit breaker retracts into the cradle, each finger of the circuit breaker contacts each terminal.

An inrush current may occur between the terminals and the fingers of the circuit breaker when the circuit breaker retracts or extends into or from the cradle. When an arc caused by the inrush current occurs between the terminals and the fingers of the circuit breaker, the arc may cause a fault in the line. Therefore, an insulating shutter is used to quickly insulate the terminal and the circuit breaker from each other when the circuit breaker retracts or extends into or from the cradle.

A conventional insulating shutter has inconvenience in that a separate actuating lever works to convert the shutter to an insulated or non-insulated mode. In addition, the conventional insulation shutter has a problem in that insulation may not be performed quickly due to the operation of the actuating lever.

In addition, according to the prior art, an insulating shutter has one portion coupled to the circuit breaker and the opposite portion coupled to the cradle, and is automatically opened or closed when the circuit breaker retracts or extends into or from the cradle. However, this insulating shutter has disadvantages in that assembly and disassembly thereof are cumbersome, and the shutter does not respond quickly when the circuit breaker retracts or extends into or from the cradle,
<CIT> discloses a shutter system for a switchgear compartment. The shutter system includes a moveable shutter translatable between a closed position and an open position. Also included is a pusher operatively coupled to a first side of the moveable shutter and configured to impart a force on the moveable shutter in response to an insertion of an electrical device within the switchgear compartment. Further included is a cam member having a cam shaft operatively coupled to the moveable shutter, the cam shaft having a cam track. <CIT> discloses an insulated protector in a universal breaker. The protector comprises a contact casing formed by connecting a backseat with a separator plate seat. An isolator is arranged outside the separator plate seat and the isolator comprises a first separator plate and a second separator plate, and each separator plate is provided with through holes at positions corresponding to the jacks. When a conductive busbar is inserted into jacks, the first separator plate and the second separator plate move to positions that the through holes of the separator plates just face the corresponding jacks, so that the conductive busbar penetrates the through holes and jacks and is connected with a bridge-shaped contact. After that the conductive busbar is withdrawn from the jacks, the first separator plate and the second separator plate move to positions that jacks in the upper and lower rows are enclosed. <CIT> discloses a switchgear interlock system that includes a circuit breaker with clusters of connector fingers separated from each other by respective cluster shields. In a connected position, the connector fingers engage respective bus connectors of bus bars for electrical contact. When the circuit breaker is disconnected from the bus bars, independently movable shutters cover access to the bus connectors to prevent inadvertent contact with the bus connectors. Each shutter includes a pedestal with an attached movable mount and movable curtain. As the circuit breaker is moved into the connected position, the mount slides along the pedestal towards the bus connector causing the curtain to open and allow the connector fingers to engage the bus connectors. As the circuit breaker is being disconnected, a return spring causes the mount to slide along the pedestal away from the bus connectors causing the curtain to close and prevent access to the bus connectors.

A purpose of the present disclosure is to provide a safety shutter for an extendable air circuit breaker that may be easily maintained and repaired, and that may quickly activate or deactivate insulation when the circuit breaker retracts or extends into or from a cradle.

Purposes of the present disclosure are not limited to the above-mentioned purpose, Other purposes and advantages of the present disclosure that are not mentioned above may be understood based on following descriptions, and will be more clearly understood with reference to embodiments of the present disclosure. Further, it will be readily apparent that the purposes and advantages of the present disclosure may be realized using means and combinations thereof indicated in the Claims.

A safety shutter configured to achieve the purpose includes a base unit coupled to a cradle for an air circuit breaker, wherein a terminal connected to a main circuit passes through the base unit; a shutter unit coupled to the base unit while being spaced apart from the base unit by a predetermined spacing, wherein the terminal is accommodated in a space defined between the shutter unit and the base unit; and a cam unit extending from the base unit in a protruding manner, wherein the cam unit passes through the shutter unit.

When the circuit breaker moves toward the base unit and retracts into the cradle, the shutter unit exposes the terminal toward the circuit breaker such that the terminal and the circuit breaker are electrically connected to each other. When the circuit breaker moves away from the base unit and extends from the cradle, the terminal is accommodated in the space between the base unit and the shutter unit such that the terminal and the circuit breaker are electrically insulated from each other.

In one implementation of the safety shutter, the base unit includes: a base plate having at least one opening defined therein through which the terminal passes, wherein the base plate is coupled to the cradle; and at least one the guide member extending from the base plate in a protruding manner along a direction in which the terminal passes through the opening, wherein the shutter unit moves along an extension direction of the guide member.

In one implementation of the safety shutter, the shutter unit includes: a holding plate having each opened or closed hole defined therein through which each terminal passes when the circuit breaker retracts into the cradle; a first plate coupled to the holding plate, wherein the first plate slides in a first direction or a second direction while moving along the cam unit, thereby to open or close a corresponding opened or closed hole; and a second plate coupled to the holding plate, wherein the second plate slides in the second direction or the first direction while moving along the cam unit, thereby to open or close a corresponding opened or closed hole.

In one implementation of the safety shutter, when a speed at which the circuit breaker retracts is equal to a speed at which the circuit breaker extends, the opened or closed hole of the shutter unit is closed in a faster manner than the opened or closed hole thereof is opened.

In one implementation of the safety shutter, the cam unit includes: a first rail constructed to allow the first plate to slide in the second direction along the first rail when the circuit breaker retracts, and to allow the first plate to slide in the first direction along the first rail when the circuit breaker extends; and a second rail constructed to allow the second plate in the first direction along the second rail when the circuit breaker retracts, and to allow the second plate to sidle in the second direction along the second rail when the circuit breaker extends.

In one implementation of the safety shutter, each of the first rail and the second rail includes: an in-cam for guiding the first plate or the second plate to slide in the first direction or the second direction along the in-cam when the circuit breaker retracts; and an out-cam for guiding the first plate or the second plate to slide in the second direction or the first direction along the out-cam when the circuit breaker extends.

In one implementation of the safety shutter, each of the in-cam and the out-cam includes an inclined side face having a predetermined angle relative to an imaginary straight line along a direction in which the circuit breaker retracts or extends, wherein each inclined side face is in contact with at least a portion of the first plate or the second plate to guide the sliding of the first plate or the second plate in the first direction or the second direction.

In one implementation of the safety shutter, an angle defined between the inclined side face of the in-cam and the imaginary straight line along the direction in which the circuit breaker retracts or extends is smaller than an angle defined between the inclined side face of the out-cam and the imaginary straight line.

In one implementation of the safety shutter, each of the first plate and the second plate acts as an electrical insulator.

In one implementation of the safety shutter, the guide member includes: a fixing member coupled to an end of the guide member to fix the shutter unit such that the shutter unit is not separated from the guide member; and an elastic member surrounding the guide member and providing an elastic force to move the shutter unit away from the base unit.

The safety shutter according to the present disclosure has an advantage of quickly activating or deactivating the insulation when the circuit breaker retracts or extends into or from the cradle.

In addition, the safety shutter according to the present disclosure has an effect of quickly activating insulation when the circuit breaker extends from the cradle, thereby preventing occurrence of an arc accident.

Further, according to the present disclosure, the shutter unit may be easily separated from the base unit of the safety shutter, and thus maintenance and repair thereof may be convenient.

The above-described effects, and specific effects of the present disclosure as not mentioned above will be described based on specific details for carrying out the disclosure.

The above objects, features and advantages will be described in detail later with reference to the accompanying drawings. Accordingly, a person with ordinary knowledge in the technical field to which the present disclosure belongs will be able to easily implement the technical idea of the present disclosure. In describing the present disclosure, when it is determined that a detailed description of a known component related to the present disclosure may unnecessarily obscure gist the present disclosure, the detailed description is omitted.

Hereinafter, a preferred embodiment according to the present disclosure will be described in detail with reference to the accompanying drawings. In the drawings, the same reference numerals are used to indicate the same or similar elements.

Hereinafter, a safety shutter according to some embodiments of the present disclosure will be described.

<FIG> shows a safety shutter and an extendable air circuit breaker according to an embodiment of the present disclosure.

As shown in <FIG>, a safety shutter <NUM> according to the present disclosure may be coupled to a cradle <NUM> into which the circuit breaker retracts. In one embodiment of the present disclosure, a front face of the cradle <NUM> is opened, and thus the circuit breaker retracts into the cradle <NUM> through the open front face.

A plurality of terminals <NUM> protruding toward the front face are arranged on an inner face of a rear portion of the cradle <NUM>. The terminal <NUM> acts as a conductor connected to a main circuit. When the circuit breaker retracts into the cradle <NUM>, each finger of the circuit breaker is electrically connected to each terminal <NUM>.

<FIG> is a perspective view of a safety shutter according to an embodiment of the present disclosure. <FIG> is a perspective view showing an open state of a safety shutter according to an embodiment of the present disclosure. <FIG> is an exploded perspective view of a safety shutter according to an embodiment of the present disclosure.

As shown in <FIG>, the safety shutter <NUM> according to the present disclosure includes a base unit <NUM>, a shutter unit <NUM>, and a cam unit <NUM>.

The base unit <NUM> is coupled to the cradle <NUM> for the air circuit breaker. When the safety shutter <NUM> is coupled to the cradle <NUM>, the terminal <NUM> connected to the main circuit passes through the base unit <NUM>.

The shutter unit <NUM> is coupled to the base unit <NUM> while being spaced apart therefrom by a predetermined spacing. The terminal <NUM> is accommodated in a space between the shutter unit <NUM> and the base unit <NUM>.

The cam unit <NUM> protrudes from the base unit <NUM>. When the base unit <NUM> and the shutter unit <NUM> are combined to each other, the cam unit <NUM> passes through a first cam unit receiving hole formed in the shutter unit <NUM>.

When the circuit breaker retracts toward the base unit <NUM>, the shutter unit <NUM> may expose the terminal <NUM> toward the circuit breaker to deactivate insulation. When the circuit breaker extends away from the base unit <NUM>, the terminal <NUM> may be received in the space between the base unit <NUM> and the shutter unit <NUM> to insulate the terminal.

Hereinafter, each of components is described in more detail.

The base unit <NUM> includes a base plate <NUM> and a guide member <NUM>.

In an embodiment of the present disclosure, the base plate <NUM> may be a plate-shaped member. However, the shape of the base plate <NUM> may vary depending on embodiments. The base plate <NUM> has an opening <NUM> defined therein through which the terminal <NUM> passes.

The guide member <NUM> protrudes upwardly from the base plate <NUM>. When the shutter unit <NUM> is coupled to the base plate <NUM> via the guide member <NUM>, the shutter unit <NUM> may move along a longitudinal direction of the guide member <NUM>.

The guide member <NUM> is received in an elastic member <NUM>. One end of the elastic member <NUM> is in contact with the base plate <NUM> while the other end thereof is in contact with the shutter unit <NUM>. Therefore, when the base plate <NUM> and the shutter unit <NUM> gets closer to each other due to an external force, the elastic member <NUM> is elastically compressed. Conversely, when the external force is removed, the elastic member <NUM> pushes the shutter unit <NUM> away from the base plate <NUM>.

<FIG> is a side view of a safety shutter according to an embodiment of the present disclosure. <FIG> is an exploded plan view of a shutter unit of a safety shutter according to an embodiment of the present disclosure. <FIG> shows a state in which a first plate and a second plate of a safety shutter according to an embodiment of the present disclosure moves. <FIG> shows a cam unit of a safety shutter according to an embodiment of the present disclosure.

As shown in <FIG> and <FIG>, a fixing member <NUM> may be coupled to an end of the guide member <NUM> passing through the shutter unit <NUM>. The fixing member <NUM> fixes the shutter unit <NUM> so that the shutter unit <NUM> moving away from the base plate <NUM> due to the elastic force of the elastic member <NUM> is maintained to be spaced from the base plate <NUM> by a predetermined distance.

The shutter unit <NUM> includes a holding plate <NUM>, a first plate <NUM> and a second plate <NUM>. When the holding plate <NUM> is coupled to the first plate <NUM> and the second plate <NUM>, each of the first plate <NUM> and the second plate <NUM> may slide only in a first direction or a second direction.

The holding plate <NUM> has a first cam unit receiving hole <NUM>, a shutter rail <NUM>, an opened or closed hole <NUM> and a coupling hole <NUM> defined therein.

The first cam unit receiving hole <NUM> is formed at a position corresponding to a position of the cam unit <NUM> protruding upwardly from the base plate <NUM>. The first cam unit receiving hole <NUM> has a planar shape corresponding to a planar shape of the cam unit <NUM> so that the cam unit <NUM> may pass through the hole <NUM> without interference at any vertical level. Specifically, the first cam unit receiving hole <NUM> has a sufficient size and a shape so that no interference occurs between the cam unit and the holding plate while an entire vertical dimension of the cam unit <NUM> passes through the hole <NUM>.

The shutter rail <NUM> accommodates therein the first plate <NUM> and the second plate <NUM>. The shutter rail <NUM> provides a path along which each of the first plate <NUM> and the second plate <NUM> slides in the first direction or the second direction.

The opened or closed hole <NUM> is opened or closed by each of the first plate <NUM> and the second plate <NUM> when each of the first plate <NUM> and the second plate <NUM> slides in the first direction or the second direction.

Specifically, when the circuit breaker retracts into the cradle, the holding plate <NUM> comes into contact with the circuit breaker and then then moves toward the base plate <NUM>. Thus, the first plate <NUM> or the second plate <NUM> comes into contact with and is engaged with a first rail <NUM> or a second rail <NUM> of the cam unit <NUM> which will be described later.

For example, the first plate <NUM> comes into contact with and is engaged with the first rail <NUM>, and slides in the second direction while moving along an inclined face of the first rail <NUM>. Further, the second plate <NUM> comes into contact with and is engaged with the second rail <NUM>, and slides in the first direction while moving along an inclined surface of the second rail <NUM>.

When the first plate <NUM> and the second plate <NUM> slide in opposite directions, each of a first opening <NUM> and a second opening <NUM> are aligned with each of the opened or closed holes <NUM>, and thus each of the opened or closed holes <NUM> is opened. Accordingly, each of the terminal <NUM> passes through each of the opened or closed holes <NUM> and protrudes forwardly of the holding plate <NUM>.

To the contrary, when the circuit breaker extends from the cradle, the holding plate <NUM> moves away from the base plate <NUM>.

Therefore, on the contrary to a case when the circuit breaker retracts into the cradle, the first plate <NUM> comes into contact with and is engaged with the first rail <NUM>, and slides in the first direction while moving along the inclined surface of the first rail <NUM>. At the same time, the second plate <NUM> comes into contact with and is engaged with the second rail <NUM> and slides in the second direction while moving along the inclined surface formed on the second rail <NUM>.

When the circuit breaker extends from the cradle and the holding plate <NUM> moves away from the base plate <NUM>, each of the first plate <NUM> and the second plate <NUM> returns to each of original positions thereof. Thus, the opened or closed holes <NUM> are respectively misaligned with the first opening <NUM> and the second opening <NUM>. Accordingly, each of a portion of the first plate <NUM> and a portion of the second plate <NUM> closes each of the opened or closed holes <NUM>.

In summary, when the circuit breaker retracts into the cradle, each opened or closed hole <NUM> is opened. Each terminal <NUM> passes through each open opened or closed hole <NUM> and protrudes forwardly of the holding plate <NUM>.

When the circuit breaker extends from the cradle, each of the opened or closed holes <NUM> is closed. Just before the opened or closed hole <NUM> is closed, the terminal <NUM> moves rearwardly of the shutter unit <NUM>. This expression is intended to simplify the description. However, precisely, the terminal <NUM> is fixed, and the shutter unit <NUM> moves forwards so that the terminal <NUM> is accommodated in the space between the shutter unit <NUM> and the base unit <NUM>.

The coupling hole <NUM> acts as a passage through which the guide member <NUM> passes. When the holding plate <NUM> moves toward or away from the base plate <NUM>, the guide member <NUM> moves within the coupling hole <NUM>.

The first plate <NUM> and the second plate <NUM> have the same configuration. Further, each of the first plate <NUM> and the second plate <NUM> acts an insulator. However, positions in the first plate <NUM> and the second plate <NUM> at which a second cam unit receiving hole <NUM> and a third cam unit receiving hole <NUM> are formed respectively are different from each other.

The first plate <NUM> has the second cam unit receiving hole <NUM>, the first opening <NUM> and a first elongate hole <NUM> defined therein.

The second plate <NUM> has the third cam unit receiving hole <NUM>, the second opening <NUM> and a second elongate hole <NUM> defined therein.

The second cam unit receiving hole <NUM> allows the first plate <NUM> to slide in the first direction or the second direction while moving along the inclined surface of the first rail <NUM> of the cam unit <NUM>.

Further, the first rail <NUM> of the cam unit <NUM> includes an in-cam <NUM> that the second cam unit receiving hole <NUM> contacts when the circuit breaker retracts from the cradle and an out-cam <NUM> that the second cam unit receiving hole <NUM> contacts when the circuit breaker extends from the cradle.

Each of the in-cam <NUM> and the out-cam <NUM> is embodied as each of the inclined side surfaces of the cam unit <NUM> having a predetermined angle. Accordingly, the second cam unit receiving hole <NUM> is formed by opening at least a portion of the first plate <NUM> and is in contact with the first rail <NUM> of the cam unit <NUM> and moves along the inclined surface of the first rail <NUM>. Accordingly, the first plate <NUM> slides in the first direction or the second direction.

The first opening <NUM> may have the same size and shape as the opened or closed hole <NUM>. Alternatively, the first opening <NUM> may have a sufficient size and shape such that the terminal <NUM> may pass through the opening <NUM> while not interfering with the opening <NUM>.

The first plate <NUM> and the second plate <NUM> are coupled to the holding plate <NUM> so that the first opening <NUM> does not overlap with the second opening <NUM>. Therefore, the opened or closed hole <NUM> is closed when the circuit breaker extends from the cradle.

As described above, when the circuit breaker retracts into the cradle, the first opening <NUM>, the second opening <NUM>, and the opened or closed hole <NUM> are aligned with each other, such that the opened or closed hole <NUM> is opened.

The first elongate hole <NUM> extends to have a predetermined length along the sliding direction of each of the first plate <NUM> and the second plate <NUM>. The guide member <NUM> passes through the first elongate hole <NUM>. Each first elongate hole <NUM> has the predetermined length so that each of the first plate <NUM> and the second plate <NUM> may slide without interfering with the guide member <NUM> while the circuit breaker retracts or extends into or from the cradle.

The third cam unit receiving hole <NUM>, second opening <NUM> and second elongate hole <NUM> included in the second plate <NUM> have the same configurations as those included in the first plate <NUM>.

As shown in <FIG> and <FIG>, the opened or closed hole <NUM> is opened or closed by each of the first plate <NUM> and the second plate <NUM> while each of the first plate <NUM> and the second plate <NUM> slides.

When the opened or closed hole <NUM> is opened, the insulation is deactivated. When the opened or closed hole <NUM> is closed, the insulation is activated.

The cam unit <NUM> may be divided into a closing area <NUM> and an opening area <NUM>.

As shown in <FIG>, the closing area <NUM> refers to a section where the shutter unit <NUM> stays in the closed state of the opened or closed hole <NUM>.

The opening area <NUM> refer to a section where the shutter unit <NUM> stays in the open state of the opened or closed hole <NUM>.

When the opened or closed hole <NUM> is opened, the terminal <NUM> passes through the opened or closed hole <NUM> and protrudes forwardly.

As described above in describing the coupling relationship between the cam unit <NUM> and the shutter unit <NUM>, the cam unit <NUM> includes the first rail <NUM> and the second rail <NUM>.

Each of the first rail <NUM> and the second rail <NUM> include the in-cam <NUM> and the out-cam <NUM>.

The in-cam <NUM> may has the inclined surface that guides the first plate <NUM> or the second plate <NUM> when the circuit breaker retracts into the cradle. Further, the out-cam <NUM> may has the inclined surface that guides the first plate <NUM> or the second plate <NUM> when the circuit breaker extend from the cradle.

The inclined surface of each of the in-cam <NUM> and the out-cam <NUM> defines a predetermined angle relative to an imaginary straight line drawn along a direction in which the shutter unit <NUM> moves or an imaginary straight line drawn along a direction in which the circuit breaker retracts or extends.

In this connection, an angle "a" between the inclined surface of the in-cam <NUM> and the imaginary straight line along the direction in which the circuit breaker retracts or extends is determined such that when the first plate <NUM> or the second plate <NUM> is in contact with the inclined surface, a friction force is lower and the first plate <NUM> or the second plate <NUM> slides smoothly. Specifically, "a" may be smaller than <NUM> degrees.

However, an angle "b" between the inclined surface of the out-cam <NUM> and the imaginary straight line along the direction in which the circuit breaker retracts or extends is larger than the angle "a".

Under this configuration, when the circuit breaker extends from the cradle, the opened or closed hole <NUM> is quickly closed because the out-cam <NUM> is involved in the opening and closing of the opened or closed hole <NUM>. Therefore, when the circuit breaker extends, a time for which the terminal <NUM> is in the non-insulated state may be reduced.

The safety shutter according to the present disclosure may reduce the inrush current between the terminal <NUM> and the circuit breaker and the occurrence of arc due to the inrush current.

Claim 1:
A safety shutter (<NUM>) for an air circuit breaker adapted to be coupled to a cradle, the safety shutter (<NUM>) comprising:
a base unit (<NUM>);
a shutter unit (<NUM>) coupled to the base unit (<NUM>); and
a cam unit (<NUM>) extending from the base unit (<NUM>) in a protruding manner, wherein the cam unit (<NUM>) passes through the shutter unit (<NUM>), wherein the shutter unit (<NUM>) includes:
a holding plate (<NUM>) having a hole (<NUM>), and
a first plate (<NUM>) having a first opening (<NUM>);
a second plate (<NUM>) having a second opening (<NUM>),
wherein the first plate (<NUM>) is configured to slide in a second direction and the second plate (<NUM>) is configured to slide in a first direction opposite to the second direction, when the air circuit breaker moves toward the base unit (<NUM>) and retracts into the cradle (<NUM>), whereby the first opening (<NUM>) and the second opening (<NUM>) are aligned with the hole (<NUM>),
wherein the first plate (<NUM>) is configured to slide in the first direction and the second plate (<NUM>) is configured to slide in the second direction, when the air circuit breaker moves away from the base unit (<NUM>) and extends from the cradle (<NUM>), whereby the first opening (<NUM>) and the second opening (<NUM>) are misaligned with the hole (<NUM>),
characterized in that
the shutter unit (<NUM>) is spaced apart from the base unit (<NUM>) by a predetermined spacing,
the first plate (<NUM>) is disposed between the base unit (<NUM>) and the holding plate (<NUM>),
and in that the second plate (<NUM>) is disposed between the first plate (<NUM>) and the base unit (<NUM>).