Compact auxiliary connector

A compact auxiliary connector can include two bushings each with an electrical connector(s), and a tubing connected between the two bushings to insulate an electrical cable, which is connected between electrical connectors of the two bushings. The electrical connector of each of the two bushings can be connected to an electrical device, a line or load bus or a combination thereof, according to the desired connection configuration. Each bushing may also include a flexible joint cover, such as a boot, to cover the connection of the bushing connectors to a bus, such as a primary bus. The compact auxiliary connector can manage live connections between auxiliary or other device(s) and line/load buses in a switchgear cabinet of a switchgear assembly. The bushings, tubing and flexible joint cover can be formed of insulating materials having desired dielectric strength according to the voltage applications.

TECHNICAL FIELD

The present disclosure relates to cable and bus assembly for a switchgear assembly, and more particularly, to a compact connector assembly for a switchgear assembly.

BACKGROUND

In medium voltage (MV) switchgear applications, voltage and control power (CP) transformers may be mounted vertically next to each other in a compartment(s) (e.g., a cubicle(s)) of a cabinet of a switchgear (also referred to as a switchgear assembly). The primary connection to these transformers is typically cables or buses, which are connected to the line or load side bus within the switchgear. When a common source is required for both of the transformers, a bus or cable connection is also made between each component. These bus or cable connections in 15,000 volt applications may require a certain air gap or insulating means to properly manage the required electrical clearances. Because of the complexity of these bus and cable connections, the primary compartment or area designated for making these connections can have a depth of at least 14 to 15 inches.

SUMMARY

To address these and other shortcomings, a connector assembly is provided for connecting a bus to one or more auxiliary devices in a switchgear assembly, in accordance with an embodiment. The connector assembly can include first and second bushing assemblies. Each of the first and second bushing assemblies can include: a bushing having opposing first and second open ends with a cavity extending therethrough, the cavity being separated by a wall into first and second cavities which open to first and second open ends respectively, the wall having an opening extending between the first and second cavities, the bushing formed of an insulating material; a connector formed of a conductive material and arranged in the cavity, the connector having a portion extending through the opening of the interior wall, the connector having a first end with a first terminal in the first cavity of the bushing and an opposing second end in the second cavity; and a flexible joint cover connectable over a portion of the bushing to enclose the second cavity with the second end of the connector, the flexible joint cover having a first slot through which to receive a conductor from a line or load bus for connection to the second end. The connector assembly can further include a tubing, connected between the flexible joint covers of the first and second bushing assemblies, for housing a conductive cable which is connected between the second ends of the connectors of the first and second bushing assemblies.

In some embodiments, the second end of the connector can include at least two second terminals separated from each other. The conductive cable can be connected between one of the two second terminals of the first bushing assembly and one of the two second terminals of the second bushing assembly.

The various embodiments, the first terminal of the connector for each of the first and second bushing assemblies can be configured to connect to a terminal of a device in a compartment of a switchgear cabinet of a switchgear assembly. The first device can be a control power transformer or a voltage transformer. The first and second bushing assemblies along with the tubing can utilize 5.5 or fewer inches in depth of a primary compartment of the switchgear cabinet to electrically connect a line or load bus to the first device. The first and second bushing assemblies together with the tubing can be configured to operate in a voltage class of 15 kV, 95 kV Basic Insulation Level (BIL).

In some embodiments, the flexible joint cover can be a polyvinyl chloride (PVC) boot which is detachably connectable over the portion of the bushing to enclose the second cavity with the second end. The tubing can be a phenolic tube. Each connector of the first and second bushing assemblies can have a Z-shape.

In accordance with a further embodiment, a switchgear assembly can include: a switchgear cabinet including an auxiliary compartment, a cable compartment and a bus bar compartment; a multi-phase power bus system including line and load buses for distributing multi-phase power; a first device in the auxiliary compartment of the switchgear cabinet; and a plurality of the connector assemblies each for a respective power phase, each of the connector assemblies having the first terminal of the connector of one of the first or second bushing assembly connected to the first device for a respective power phase and the second end of the connector of the first or second bushing assembly connected to a respective power phase of the line or load bus of the multi-phase power bus system.

In some embodiments, the switchgear assembly can further include a second device in the auxiliary compartment of the switchgear cabinet, and the first and second devices can be mounted vertically next to one another in the auxiliary compartment. Each of the connector assemblies can have the first terminal of the other one of the first or second bushing assembly connected to the second device for a respective power phase. Furthermore, the first device can be a control power transformer and the second device is a voltage transformer. The first and second bushing assemblies along with the tubing can utilize 5.5 or fewer inches in depth of the switchgear cabinet to electrically connect a line or load bus to the first device. Each of the connector assemblies can be configured to operate in a voltage class of 15 kV, 95 kV Basic Insulation Level (BIL).

Identical reference numerals have been used, where possible, to designate identical elements that are common to the figures. However, elements disclosed in one embodiment may be beneficially utilized on other embodiments without specific recitation.

DETAILED DESCRIPTION

A compact auxiliary connector can include two bushings each with an electrical connector(s), and a tubing (or “tube”) connected between the two bushings to insulate an electrical cable, which is connected between electrical connectors of the two bushings. The electrical connector of each of the two bushings can be connected to an electrical device, a bus (e.g., for line or load) or a combination thereof, according to the desired connection configuration. Each bushing may also include a flexible joint cover, such as a boot, to cover the connection of the bushing connectors to a bus, such as a primary bus. The compact auxiliary connector can manage live connections between auxiliary or other device(s) and line/load buses in a switchgear cabinet (or enclosure) of a switchgear assembly. The bushings, tubing and flexible joint cover can be formed of insulating materials having desired dielectric strength according to the voltage applications.

The compact auxiliary connector of the present disclosure can allow a significant reduction in parts and compartment size for supporting, for example, medium voltage primary connections to auxiliary transformers. This reduction is valuable in allowing a reduced equipment depth while maintaining a safe and reliable live part connection in small enclosures. For example, the use of such compact auxiliary connectors as described herein can be more economical than using increased enclosure size with bus bars and insulators. Furthermore, the design of the connector assembly can also sufficiently manage strike and tracking distances and dielectric strength at desired rated voltage, such as for medium or other voltage applications (e.g., 15 kV, 95 kV Basic Insulation Level (BIL) applications). The compact auxiliary connector can also allow live parts to be safely mounted within a compartment of 5.5 inches (or 139.7 mm) of grounded metal. The compact auxiliary connector can provide adequate air clearances between live parts and grounded metal to avoid dangerous potential partial discharge issues.

An example compact auxiliary connector will be described below with reference to the figures, in accordance with the present disclosure.

FIG.1shows a partial view of an example switchgear assembly10, which includes a switchgear cabinet100for housing switching and auxiliary devices, electrical connectors/cabling and bus bars. In this example, the switchgear assembly10is for a multi-phase power distribution system, such as a three-phase power distribution system. The switchgear cabinet100can include a plurality of compartments for housing switching and/or auxiliary devices, electrical cables and conductors, bus bars for line and load, and other components. The compartments can, for example, include: a switching and/or auxiliary compartment(s)110for housing switching and/or auxiliary electrical device(s) such as circuit breakers, transformers and other protective devices; a bus bar compartment(s)112(not shown) for housing line and load bus bars connected to a power source and various loads, respectively; and a cable compartment(s)114for housing conductors or electrical cables (generally referred to as cables) which connect various devices, bus bars and other components in the switchgear cabinet10. In this example, the auxiliary compartment(s) can house auxiliary devices, such as a control power (CP) transformer120and a voltage transformer122, which are vertically stacked, e.g., one above the other, in the auxiliary compartment(s)110of the switchgear cabinet100. A compartment116, which is referred to as a primary compartment, is where connection is made between electrical equipment (e.g., medium voltage equipment) and a primary bus130.

As further shown inFIG.1, a compact auxiliary connector150is provided for each power phase to electrically connect the transformers120and122and a bus, such as the primary bus130, to each other. As shown inFIGS.1and2, the primary bus130(e.g., of a line bus), for each phase can be connected to a respective compact auxiliary connector150. An epoxy can be applied to a portion of a conductor132of the primary bus130, which would otherwise be exposed, when connected to the compact auxiliary connector150in the primary compartment116. The conductor132can be a flat conductor with one end connected or connectable to a cable of the primary bus130, and the other end connectable to the compact auxiliary connector150(or a conductor therein). The epoxy can be formed of a dielectric material or other insulating material. The primary compartment116can have a depth D, as shown inFIG.2.

FIG.3illustrates a perspective view of the plurality of compact auxiliary connector(s)150ofFIG.1with a portion of bushing assemblies of one of the connectors cut out to provide an internal view of the connectors and components therein, in accordance with an embodiment. As shown inFIG.3, each compact auxiliary connector150can include two bushing assemblies300A,300B (each assembly also referred generally as “300”). Each bushing assembly300A,300B includes a bushing310with an electrical connector320therein, and a flexible joint cover330for covering a portion of the bushing310and connections therein. The compact auxiliary connector150also includes tubing (or tube)340which is connected between the two bushing assemblies300A and300B and houses an electrical cable350which is connected between the electrical connectors320of the two bushing assemblies310A,310B. Although the tubing340is shown as being cylindrical in shape, the tubing340can have any suitable shape, size and/or length according to the application. The tubing340can be formed of an insulating material. In this example, the tubing340can be a phenolic tubing.

As further shown inFIG.4, the bushing310includes a cavity410therein. The bushing310also includes a wall412(e.g., wall, partition, etc.), which separates the cavity140into a first cavity410A and a second cavity410B each of which open to first and second open ends respectively. The wall412includes an opening414, which extends between the first and second cavities410A and410B and receives a portion of the connector320therethrough. The bushing310also includes an opening416for receiving an open-end portion of the tubing340. The bushing410can be formed of an insulating material. The bushing310can have a generally cylindrical shape. In this example, the first cavity410A has a cross-sectional area, which is smaller than the second cavity410B (e.g., the diameter of the first cavity410A is smaller than the diameter of the second cavity410B). The bushing310and portion thereof can be a rigid component, which can have any desired size, shape or dimension depending on the application. For example, the size and shape of the open-ended portion of the bushing310with the first cavity410A can be configured to engage a connector assembly of devices connectable thereto, such as the auxiliary and other devices, described herein. When connected, the device connection to the connector320is covered. The bushing310can be formed as a single (or unitary piece) or multiple pieces connected together.

The connector320is formed of a conductive material, and has a first end420and a second end430. The connector320has a portion thereof, which extends through the opening414of the wall412and is supported by the wall412. The first end420of the connector320is arranged in the first cavity410A, and the second end430of the connector320is arranged in the second cavity410B. The first end420includes a first terminal422for connecting to a conductor. In this example, the first terminal422can be configured to connect to an electrical device, such as an auxiliary or other device of a switchgear assembly (e.g., transformer). The second end420can include a plurality of terminals, such as for example two separate second terminals432A,432B. In this example, the second terminal432A can be configured to connect to a bus conductor, such as for example, the conductor132of the primary bus130. The other second terminal432B can be configured to connect to a conductor, such as the cable350which is connected between the second terminals432B of the connectors320of the two bushing assemblies310A,310B (e.g., inFIG.3). The first and second terminals can employ various electrical fasteners or fastening configurations to connect the connector320to a conductor of a device, bus or other electrical component. In this example, the connector320is a flat conductor with a Z-shape; however, the connector320can have any suitable size and shape depending on the application.

The flexible joint cover330is configured to connect over a portion of the bushing310to enclose the second cavity410B with the second end430of the connector320and cover any connection to the second end420. The joint flexible cover330includes a first extending portion440with a slot442through which to receive a conductor, such as for example from a line or load bus for connection to the second end430in the cavity410B of the bushing310. In this example, the conductor is the conductor132of the primary bus130. The first extending portion440can have a rectangular shape. The flexible joint cover330also includes a second extending portion444with a channel446for receiving an end portion of the tubing340, which has portion thereof engaged through the opening416of the bushing310. The walls of the extending portion444may extend fully or partially around the portion of the tubing340. In this example, the extending portion444extends partially around the portion of the tubing340to allow removal of the flexible joint cover330even when the tubing340is engaged in the opening416of the bushing310. The flexible joint cover330can take the form of a boot which can be detachably connectable over an open portion of the bushing310to cover a connection(s) to the second end430of the connector320, and can be made of Polyvinyl Chloride (PVC) or other flexible insulating material.

An operational installation example is described below with reference to the components of the switchgear assembly10ofFIGS.1-4. In this example, the control power transformer120is vertically stacked on top of the voltage transformer122in the cabinet100. For each phase, the first end420of the connectors320of the bushing assemblies300(e.g.,300A and300B) of one compact auxiliary connector150is connected to a connection assembly (or conductor) of the transformers120and122, respectively. The conductor132of the primary bus130is extended through the slot442of the flexible joint cover330, and connected to the second terminal432A of the connector320of one of the bushing assemblies (e.g.,300A) in the cavity410B. The flexible joint cover330can then be pulled over a portion of the bushing310to enclose the cavity410B and cover the connection to the second end430of the connector320.

This process can be repeated with other compact auxiliary connectors150to make the connections for the other phases. The reverse process can be performed to disconnect the transformers120and122from the primary bus130. The above is simply one example of the different connection configurations, which can be made between device(s) and bus(es) in a switchgear assembly or other electrical enclosure. The compact auxiliary connector(s)150can be employed to connect different types and numbers of devices to different types and numbers of buses in a power distribution system.

In various embodiments, the compact auxiliary connector, described herein, can manage, among other things, the following: live part connection to an auxiliary device (e.g., transformer fuse of a transformer); live part connection to a primary bus; and cable connection housed in a phenolic tubing to make primary connection to two auxiliary devices (e.g., two transformers such as control power transformer and voltage transformer). Epoxy can be used on the primary bus coupled with a flexible joint cover (e.g., a boot) which can be made in a suitable size and dimension to cover an opening of the bushing and formed from a high dielectric strength flexible PVC material. The compact auxiliary connector can maintain required clearances and required tracking distance to perform in a 15 kV, 95 kvBIL application (or voltage class). Furthermore, the compact auxiliary connector can allow for a relatively small Medium Voltage (MV) primary compartment with a depth D at or around 5.5 inches (139.7 mm) or less compared to a compartment depth on some other MV switchgear assemblies which may need 14.5 inches (368.3) using cables or buses. This represents a 60% decrease in compartment size resulting in a smaller foot print for the switchgear cabinet or compartments therein.

In the preceding, reference is made to various embodiments. However, the scope of the present disclosure is not limited to the specific described embodiments. Instead, any combination of the described features and elements, whether related to different embodiments or not, is contemplated to implement and practice contemplated embodiments. Furthermore, although embodiments may achieve advantages over other possible solutions or over the prior art, whether or not a particular advantage is achieved by a given embodiment is not limiting of the scope of the present disclosure. Thus, the preceding aspects, features, embodiments and advantages are merely illustrative and are not considered elements or limitations of the appended claims except where explicitly recited in a claim(s).

It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other implementation examples are apparent upon reading and understanding the above description. Although the disclosure describes specific examples, it is recognized that the systems and methods of the disclosure are not limited to the examples described herein, but may be practiced with modifications within the scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative sense rather than a restrictive sense. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.