Patent Description:
Medium voltage and high voltage switchgear are commonly used electrical equipment in transmission and distribution lines. In order to detect the stability of the voltage in the line, voltage transformer (VT) or potential transformer (PT) is usually used. Input terminals of VT or PT are typically coupled to busbars via a switch assembly in a compartment which is used for receiving an electrical device, such as a circuit breaker. In this way, the voltage parameters of the line are obtained by measuring the low voltage at output terminals of VT or PT. In the conventional solution, the input terminals of VT or PT are arranged in the compartment.

In the known solutions, the compartment for receiving the electrical device in the switchgear or controlgear is airtight and filled with insulation gas, such as dry air, SF<NUM> or the like. Furthermore, conductive units, sometimes called conductive knives, are electrically coupled to the busbars by being inserted into clamps arranged on the busbars. For ease of insertion, the conductive units are typically thin and prone to sharp corners. The presence of sharp corners results in a spacing between the phases and between the phases and the walls that should be greater than a predetermined distance. This results in a large volume of the compartment.

<CIT> discloses a switching device including a tank, in which a current interruption unit and a drive device for driving the current interruption unit are placed. Metal electrodes having a cylindrical shape are embedded around central conductors passing through corresponding bushings.

In the conventional solution, the input terminals of VT or PT are arranged in the airtight compartment. In some cases, such as when the VT needs to be replaced, the terminals have to be removed from the compartment. This would inevitably affect the airtightness of the compartment. Furthermore, as mentioned above, the sharp corners present in the conventional switch assembly and/or busbars tend to accumulate charge. This requires a large spacing between bubars and/or between bubars and walls, which in turn leads to a larger volume of the compartment.

In order to at least partially address the above and other potential problems, embodiments of the present disclosure provide a switch assembly for a detection unit of a switchgear or controlgear as well as associated compartment and a switchgear. The switch assembly according to embodiments of the present disclosure provides more uniform electrical field distribution in the compartment, resulting in a more compact compartment and switchgear or controlgear.

In a first aspect, embodiments of the present disclosure provide a switchgear or controlgear as claimed in claim <NUM>.

By use of the connecting unit for receiving a terminal of the detection unit positioned outside the compartment, the terminals of the detection unit, such as voltage transformer (VT), are positioned outside the compartment. Maintenance or replacement of the VT will not affect the airtightness of the compartment. Furthermore, the connecting unit can also be used to receive the terminal of other kind of detection unit, such as terminals of test assemblies.

In some embodiments, each connecting unit comprises an opening end hermetically surrounding an opening formed on a bottom wall of the compartment, wherein the terminal is received in the connecting unit through the opening. In this way, the airtightness of the compartment can be ensured conveniently and easily.

In some embodiments, the switch assembly further comprises at least one bumper, each bumper arranged on an end of the conductive unit away from the shaft to avoid bounce when the conductive unit rotates to the close position or the open position. Compared to the conventional solution, by using the bumpers arranged on the end, bounce of the conductive unit when contacting the busbars or the ground can be avoided without being inserted into the clamp on the busbar. That is, the clamp on the busbar can be removed and the conductive unit can be designed to be broader or smoother to avoid sharp corners on the surface.

In some embodiments, the switch assembly further comprises at least one conductive bushing coaxially arranged on the shaft, wherein each conductive unit radially protrudes from the shaft and passes through the respective conductive bushing; and at least one elastic conductive unit arranged in the respective connecting unit, each elastic conductive unit electrically contacting the respective conductive bushing. By using the conductive bushing coaxially arranged on the shaft, the electrical connection between the conductive unit and the terminal can be maintained no matter which position the conductive unit is located. Furthermore, using the conductive bushing can avoid sharp corners caused by other methods of connecting the conductive unit with the shaft, such as welding or the like.

In some embodiments, at least one of the conductive bushing and the conductive unit is of a cylinder shape and is rounded or chamfered to avoid sharp corners on surfaces. With this arrangement, sharp corners can be further avoided and the electric field distribution in the compartment can be more uniform.

In some embodiments, the connecting unit comprises a conductive core for electrically contacting the terminal and an insulating shell enclosing the conductive core, and the conductive core comprises a receiving hole for receiving the elastic conductive unit. In this way, the electric field distribution in the compartment can be more uniform.

In some embodiments, the conductive unit and the conductive bushing are made of conductive material and/or coated with conductive coating. In this way, the conductive units and the conductive bushings and even the switch assembly can be manufactured in a cost effective way.

In some embodiments, the switch assembly further comprises a mounting sleeve arranged on one of the opposite side walls; and a coupling pin arranged on an end of the shaft and hermetically and rotatably received in the respective mounting sleeve; wherein the mounting sleeve is rounded or chamfered to avoid sharp corners on surfaces. By using the rounded or chamfered mounting sleeve, the electric field distribution in the triangle area of the compartment can be more uniform. The triangle area means that an area where the sleeve, the side wall and the shaft meet.

In some embodiments, a closed structure is formed between the conductive bushing and the shaft to prevent metal debris from escaping. In this way, even if friction exists between the bushing and the shaft, the generated metal debris is enclosed in the closed structure without escaping.

In some embodiments, the compartment comprises opposite side walls substantially parallel to each other; at least one connecting busbar evenly arranged between the opposite side walls and coupled to the electrical component; and a switch assembly mentioned above arranged between the opposite side walls; wherein the connecting busbar is rounded or chamfered. In this way, the electric field distribution in the area adjacent to the connecting busbar is more uniform. This allows the busbars to be more closer under the same insulation conditions.

In some embodiments, the connecting busbar is plate-shaped with curved ends. This allows the connecting busbar to be processed more easily.

It is to be understood that the Summary is not intended to identify key or essential features of embodiments of the present disclosure, nor is it intended to be used to limit the scope of the present disclosure. Other features of the present disclosure will become easily comprehensible through the description below.

The above and other objectives, features and advantages of the present disclosure will become more apparent through more detailed depiction of example embodiments of the present disclosure in conjunction with the accompanying drawings, wherein in the example embodiments of the present disclosure, same reference numerals usually represent same components.

The present disclosure will now be discussed with reference to several example embodiments. It is to be understood these embodiments are discussed only for the purpose of enabling those skilled persons in the art to better understand and thus implement the present disclosure, rather than suggesting any limitations on the scope of the subject matter.

As used herein, the term "comprises" and its variants are to be read as open terms that mean "comprises, but is not limited to. " The term "based on" is to be read as "based at least in part on. " The term "one embodiment" and "an embodiment" are to be read as "at least one embodiment. " The term "another embodiment" is to be read as "at least one other embodiment. " The terms "first," "second," and the like may refer to different or same objects. Other definitions, explicit and implicit, may be comprised below. A definition of a term is consistent throughout the description unless the context clearly indicates otherwise.

In the conventional switchgear or controlgear <NUM>', as shown in <FIG>, terminals <NUM>' of a detection unit <NUM>', such as voltage transformer (VT), are usually positioned in a compartment for receiving an electrical device, such as a circuit breaker or the like. However, the compartment is typically airtight and filled with dry air or SF<NUM> to improve the insulation performance. Furthermore, for the sake of testing, maintenance or repair, VT often needs to be replaced. The removing of the terminals from inside of the compartment inevitably affects or deteriorates the airtightness of the compartment.

Furthermore, as shown in <FIG> and <FIG>, a known switch assembly is used for controlling the electrical connection between the busbars <NUM>' and the VT <NUM>'. As shown, a conventional switch assembly typically comprises a clamp structure <NUM>' on the busbar to receive a conductive unit to ensure the stability of the connection therebetween. This requires the conductive unit <NUM>' called knife sometimes to be as thin as possible to facilitate insertion into the clamp. As such, at least the conductive unit of the switch assembly inevitably has sharp corners. This exacerbates the non-uniformity of the electric field distribution in the compartment and results in a wider width between the busbars and thus a larger compartment volume.

In order to at least partially address the above and other potential problems, embodiments of the present disclosure provide a switch assembly a detection unit <NUM>, such as VT, of a switchgear. Now some example embodiments will be described with reference to <FIG>.

<FIG> shows schematic diagrams of the switchgear or controlgear <NUM> according to embodiments of the present disclosure and <FIG> shows perspective view of a compartment <NUM> and a switch assembly <NUM> arranged therein according to embodiments of the present disclosure.

In general, the switch assembly <NUM> according to embodiments of the present disclosure comprises a shaft <NUM>, at least one conductive unit <NUM> and coupling mechanisms <NUM>. The switch assembly <NUM> is arranged in a compartment for receiving an electrical device <NUM> such as a circuit breaker or the like. The electrical device <NUM> is coupled to busbars <NUM> in the compartment <NUM>. The opening and closing of an electrical connection between the busbars <NUM> and the detection unit <NUM> is achieved by the movement of the conductive unit <NUM>.

The number of the conductive unit <NUM> can be determined based on the number of phases. For example, the number of conductive unit <NUM> may be <NUM>, <NUM>, <NUM> or more. Furthermore, the connecting busbar <NUM> may be any type of busbar coupled to the electrical component <NUM>. For example, in some embodiments, the connecting busbar <NUM> may be a tee-off bubars arranged in the compartment <NUM>.

The compartment <NUM> is airtight and comprises several walls including opposite side walls <NUM>, a bottom wall <NUM>, a rear wall <NUM> and the like. According to embodiments of the present disclosure, the shaft <NUM> for carrying the conductive units <NUM> is arranged between the opposite side walls <NUM> and is rotatable about its axis. The conductive units <NUM> can rotate with the shaft <NUM> between at least two positions an open position and a close position, as shown in <FIG>. In the open position, the conductive units <NUM> contact the rear wall <NUM> which is grounded. As such, the electrical connection between ground and the detection unit <NUM> is conducted.

In the close position, the conductive units <NUM> conduct the electrical connection between the coupling mechanisms <NUM> and the busbars <NUM>. The coupling mechanisms <NUM> further couple the conductive units <NUM> to the detection units <NUM>. In this way, high voltage over the busbars is conducted to the terminals <NUM> of the detection units <NUM>.

Compared to known conventional solutions, according to embodiments of the present disclosure, the terminals of the detection unit <NUM> can be positioned outside the compartment <NUM>. Accordingly, each coupling mechanism <NUM> comprises a connecting unit <NUM> for receiving the terminal of the detection unit <NUM>. In this way, when the detection unit <NUM> needs to be replaced or removed due to maintenance or repair, for example, the airtightness of the compartment <NUM> will not be affected. In addition to or instead of VT, the detection unit <NUM> can be any suitable component that can detect or test the performance of voltage over the connecting busbars <NUM>. For example, in some alternative embodiments, the detection unit <NUM> may also be a test device for testing the performance of the electrical component <NUM> such as a circuit breaker or the like.

According to embodiments of the present disclosure, the connecting unit <NUM> can receive the terminal <NUM> in any suitable ways. For example, in some embodiments, the connecting unit <NUM> may have an opening end <NUM> adjacent to the bottom walls <NUM>, as shown in <FIG> and <FIG>. The opening end <NUM> may be annular in general and may hermetically surrounds an opening <NUM> formed on the bottom wall <NUM>. In this way, the terminal <NUM> may be received in the connecting unit <NUM> through the opening <NUM>, as shown in <FIG>. This approach provides a more robust electrical connection between the connecting unit and the terminal without affecting the airtightness of the compartment <NUM>.

In some embodiments, the connecting unit <NUM> may have a conductive core <NUM> and an insulating shell <NUM> enclosing the conductive core <NUM>. The conductive core <NUM> is used to contact the terminal <NUM>. In this way, only a small portion of the conductive surface of the connecting unit <NUM> is exposed in the compartment <NUM>, which promotes the equalization of the electric field distribution in the compartment <NUM>.

The exposed portion of the conductive surface of the connecting unit <NUM> may be rounded or chamfered to obtain a further uniform electric field distribution. The insulating shell <NUM> may be of any suitable shapes. For example, in some embodiments, the insulating shell <NUM> may be of a conical shape which is rounded or chamfered, as shown in <FIG> and <FIG>.

It can be seen from <FIG> that the opening end <NUM> is the end of the insulating shell <NUM> adjacent to the bottom wall <NUM>. The opening end <NUM> may be hermetically surrounding the opening <NUM> in any suitable ways. For example, the opening end <NUM> may be fixed to the bottom wall <NUM> by gluing. In other embodiments, fasters can be used as the coupling mechanism, for example.

It is to be understood that the above embodiments of the connecting unit <NUM> are described merely for illustration, without suggesting any limitations as to the scope of the present disclosure. It is possible to use any other suitable structures or arrangements that can seal the opening <NUM> and reduce the exposed area of the conductive core. For example, in some alternative embodiments, the end of the connecting unit <NUM> adjacent to the bottom wall <NUM> may also be a plane without opening. In this plane, the insulating shell <NUM> may surround the conductive core <NUM> which is exposed to the outside of the compartment for contacting the terminal <NUM>. Alternatively, in some embodiments, at least the conductive core <NUM> of the connecting unit <NUM> may be protruded outwards from the bottom wall <NUM>. For example, in these embodiments, at least the conductive core <NUM> may forms a male terminal. In this way, the conductive core <NUM> can be connected with any type of terminals <NUM>, including flexible terminals, of the detection unit <NUM>.

As mentioned above, the conductive unit <NUM> may rotate about the shaft <NUM>. In order to maintain the electrical connection between the conductive unit <NUM> and the connecting unit <NUM>, in some embodiments, at least one conductive bushing <NUM> and elastic conductive unit <NUM> may be used. Specifically, in these embodiments, each conductive bushing <NUM> may be coaxially arranged on the shaft <NUM>. The conductive unit <NUM> may radially protrudes from the shaft <NUM> and passes through the respective conductive bushing <NUM>. The elastic conductive unit <NUM> can be received in a receiving hole <NUM> formed in the conductive core <NUM> and protrude out slightly from the receiving hole <NUM> to contact the conductive bushing <NUM>. Furthermore, this arrangement may also reduce the adhesion of the metal particles to the outer metal surface, which in turn makes the electric field distribution more uniform.

In this way, regardless of how the shaft <NUM> and the conductive unit <NUM> rotate, the elastic conductive unit <NUM> can contact the outer circumference of the conductive bushing <NUM> all the time, thereby ensuring an electrical connection between the conductive unit <NUM> and the conductive core <NUM> of the connecting unit <NUM>. In some embodiments, the conductive bushing <NUM> and the conductive unit <NUM> may have cylinder shape with edges rounded or chamfered, for example. In this way, the electric field distribution adjacent to the conductive bushing <NUM> and the conductive unit <NUM> can be further uniform.

Furthermore, the connection between the conductive bushing <NUM> and the shaft <NUM> ensures that frictional portions of the bushing <NUM> and the shaft <NUM> are enclosed in a closed structure formed therebetween. This effectively solves the problem of metal debris escaping and/or adhesion caused by friction and other problems between the frictional portions. In this way, even if friction exists between the bushing <NUM> and the shaft <NUM>, the generated metal debris is enclosed in the closed structure without escaping.

In some embodiments, the connecting busbars <NUM> arranged in the compartment <NUM> may also be rounded or chamfered. In other words, in some embodiments, the conductive components arranged in the compartment <NUM> are all have relatively rounded shape without any sharp corners. This can avoid concentration of charge caused by the sharp corners and thus ensures the uniform electric field distribution within the compartment <NUM>. The uniform electric field distribution allows for smaller distance between the busbars <NUM> under equivalent insulation conditions, resulting in a more compact compartment <NUM>.

In some embodiments, the conductive bushing <NUM> and the conductive unit <NUM> may be made by applying a conductive coating to the surface of the non-conductive component, such as plastic component or the like. This can further reduce the cost. In some embodiments, the conductive bushing <NUM> and the conductive unit <NUM> may be integrally formed. Alternatively, in other embodiments, the conductive bushing <NUM> and the conductive unit <NUM> may also be made of conductive material. The conductive material includes, but is not limited to, metal, semiconductors and the like.

In order to avoid bounce of the conductive unit <NUM> when contacting the respective busbar <NUM> or contacting the rear wall <NUM> which is grounded, in some embodiments, as shown in <FIG>, the switch assembly <NUM> may further comprises at least one bumper <NUM> each arranged on an end of the conductive unit <NUM> away from the shaft <NUM>. In those embodiments, when the conductive unit <NUM> rotates to the close position, the bumper <NUM> will contact the busbar <NUM> first, which provides a buffer for subsequent contact between the conductive unit <NUM> and the busbar <NUM>. Similarly, when the conductive unit <NUM> rotates to the open position, the bumper <NUM> will contact the rear wall <NUM> first, which provides a buffer for subsequent contact between the conductive unit <NUM> and the rear wall <NUM>.

As such, a robust electrical connection between the busbar <NUM> or the rear wall <NUM> and the conductive unit <NUM> can be ensured. Furthermore, in some embodiments, each busbar <NUM> may be plated-shaped with curved ends to further avoid sharp corners while reducing the cost, as shown in <FIG> and <FIG>.

In aid of the bumpers <NUM> to provide buffer when contacting to the busbars <NUM>, the robust connection between the conductive unit <NUM> and the busbars <NUM> can be ensured even without the clamp on the busbars <NUM>. As such, the electric field distribution balance is improved while reducing the material cost, and the entire switch assembly <NUM> can be assembled more easily.

In some embodiments, the bumpers <NUM> and/or the elastic conductive units <NUM> may be springs, for example. It to be understood that employing spring as the bumpers <NUM> and/or the elastic conductive units <NUM> in these embodiments is merely for illustration, without suggesting any limitations as to the scope of the present disclosure. Any other suitable structures or arrangements are possible as well. For example, bumpers <NUM> and/or the elastic conductive units <NUM> may also be any other suitable elastic conductive components.

In some embodiments, the shaft <NUM> is driven to rotate by a driven device (not shown), such as a motor or the like, positioned outside the compartment <NUM>. In order to connect the output of the driven device with the shaft <NUM>, a sleeve arranged on the side wall <NUM> may be used. This may result in a triangle area adjacent to the opposite side walls <NUM>. Such a triangle area is an area where the mounting sleeve <NUM>, the side wall <NUM> and the shaft <NUM> meet. The triangular region tends to cause sharp corners to make the electric field unbalanced. In order to avoid the sharp corners in the triangle area, at least the part of the mounting sleeve <NUM> arranged in the compartment <NUM> has a substantially cylinder shape and is rounded or chamfered, as shown in <FIG>. In this way, the angle formed between the shaft <NUM> and the mounting sleeve <NUM> and between the sleeve <NUM> and the side walls <NUM> effectively avoid sharp corners.

In some embodiments, a coupling pin <NUM> for coupling the output of the driven device may be arranged on an end of the shaft <NUM>. The coupling pin <NUM> may be hermetically and rotatably arranged in the mounting sleeve <NUM>. The same arrangement may be used at the other end of the shaft <NUM>. Alternatively, in some embodiments, the other end of the shaft <NUM> may also be received in a recess formed in the side wall <NUM> directly. The recess in the side wall <NUM> may be formed by stamping or any other suitable methods.

As can be seen from the above description, the switch assembly <NUM> according to embodiments of the present disclosure may achieve more uniform electrical field distribution in the compartment <NUM>. Furthermore, as for the triangle area, a uniform electrical field distribution can be obtained due to the mounting sleeve <NUM>. As a result, the distance between the busbars <NUM> may be reduced and the compartment <NUM> can be more compact under same insulation conditions.

For example, in the know solution, for a switchgear or controlgear with a width of <NUM>, SF<NUM> is needed in the compartment to achieve a voltage level of <NUM> kV. The filing of the dry air in the compartment <NUM> can only achieve the voltage level of 12kV or lower. On the contrary, with the arrangement of the switch assembly <NUM> according to embodiments of the present disclosure, for the switchgear or controlgear with a width of <NUM>, only dry air instead of SF<NUM> is required in the compartment <NUM> to achieve a voltage level of 24kV or even higher. As such, the switch assembly according to embodiments of the present disclosure makes the switchgear or controlgear more environmentally friendly.

On the other hand, as to the same filling gas, a more compact switchgear or controlgear can be achieved. For example, in the case of filling SF<NUM> in the compartment <NUM>, the switch assembly according to embodiments of the present disclosure enables a switchgear or controlgear to achieve a voltage level of <NUM> kV or higher even with a width of <NUM> or less. Furthermore, in the case of filling dry air in the compartment <NUM>, a voltage level of 12kV or higher can be achieved with a width of <NUM> or less.

In sum, by means of the switch assembly according to embodiments of the present disclosure, the switchgear or controlgear can be made more environmentally friendly and compact. It is to be understood that the above examples about the switchgear or controlgear are described merely for illustration, without suggesting any limitations as to the scope of the present disclosure. It is possible to apply the switch assembly <NUM> according to embodiments of the present disclosure to any other suitable switchgear or controlgear. For example, in some alternative embodiments, the switch assembly <NUM> can be applied to the switchgear or controlgear with a voltage level of 48kV or higher.

Moreover, with the bumpers <NUM> arranged on free ends of the conductive units <NUM>, bounce that occurs when the conductive units <NUM> contact the busbars <NUM> can be avoided. This arrangement can also effectively avoid sharp corners to obtain a more uniform electrical field distribution in this area. The conductive bushings <NUM> coupled to the elastic conductive units <NUM> arranged in the connecting units can ensure that the elastic conductive unit <NUM> contacts the outer circumference of the conductive bushing <NUM> all the time.

In addition, by use of the connecting units <NUM>, the terminals of the detection unit <NUM> can be positioned outside the compartment <NUM>. In this way, the airtightness of the compartment <NUM> will not be affected even when removing the terminals <NUM>. This arrangement may also allow the detection unit <NUM> to be any suitable device other than VT.

Claim 1:
A switchgear or controlgear (<NUM>) comprising a switch assembly (<NUM>) for a detection unit (<NUM>) of the switchgear or controlgear (<NUM>), the switchgear or controlgear (<NUM>) comprising a compartment (<NUM>) for accommodating an electrical component (<NUM>) and at least one connecting busbar (<NUM>) coupled to the electrical component (<NUM>), the switch assembly (<NUM>) comprising:
a shaft (<NUM>) rotatably arranged between opposite side walls (<NUM>) of the compartment (<NUM>);
at least one conductive unit (<NUM>), each conductive unit (<NUM>) being rotatable about the shaft (<NUM>) between an open position and a close position; and
at least one coupling mechanism (<NUM>) arranged in the compartment (<NUM>) and configured to electrically couple the conductive unit (<NUM>) to the detection unit (<NUM>),
wherein each coupling mechanism (<NUM>) is electrically coupled to the respective connecting busbar (<NUM>) when the conductive unit (<NUM>) is in the close position, and is electrically decoupled from the respective connecting busbar (<NUM>) when the conductive unit (<NUM>) is in the open position and is grounded, and
wherein the switch assembly (<NUM>) is arranged in the compartment (<NUM>), and each coupling mechanism (<NUM>) comprises a connecting unit (<NUM>) for receiving a terminal (<NUM>) of the detection unit (<NUM>) positioned outside the compartment (<NUM>).