1. Technical Field
This application relates to electrical devices and, more particularly, to electrical connectors.
2. Related Art
An electrical connector may be used to connect multiple electrical devices. One type of electrical connector is an electrical bushing that may connect a power distribution component with a power line. A first end of the bushing may include a connection terminal that connects with the power distribution component, such as a transformer. A second end of the bushing may include an opening that receives a contact pin associated with the power line. The bushing includes a current path to electrically connect the power distribution component with the power line when the contact pin is inserted into the bushing.
When the contact pin is being inserted in the bushing, either a standard connection or a fault condition connection may occur. In a standard connection, the contact pin is inserted into the bushing until a connection is made between the contact pin and a socket in the bushing. Once the standard connection is complete, current flows through the bushing between the power distribution component and the power line. For some applications, the current flow during the standard connection may be about 200 amps.
In a fault condition connection, there may be a problem somewhere in the system that causes a much higher current flow. For example, there may be a short circuit somewhere in the system. For some applications, the current flow during the fault condition connection may be about 10,000 amps. As the contact pin approaches the socket in the bushing, an electric arc may form between the socket and the contact pin. The electric arc may cause equipment damage and may be dangerous to people in the vicinity of the arc. The electric arc would be extinguished if a physical connection between the socket and the contact pin could be completed, but the electric arc causes expanding gas in the bushing that makes it very difficult to push the contact pin into the socket.
Some known electrical bushings are designed with safety features to extinguish these electric arcs. For example, the bushing may allow the socket used for the standard connection to move forward in a fault condition to make contact with the contact pin. In this arrangement, the primary current path used for the standard connection is also used for the fault current connection. To allow movement of the socket to meet the contact pin, additional contact interfaces may be required between the socket and the connection terminal. These additional contact interfaces may limit the long-term reliability of the electrical bushing when mated in the standard connection. Therefore, a need exists for an improved electrical connector for standard and fault condition connections.
An electrical connector may connect multiple electrical devices. In one implementation, an electrical connector includes a socket that is configured to provide a current path between a connection terminal and a contact pin inserted into the socket during a standard connection. A slider component of the electrical connector is configured to move relative to the socket to make contact with the contact pin and provide a current path between the connection terminal and the contact pin during a fault condition connection.
In another implementation, an electrical connector includes a fixed means for receiving a contact pin and electrically connecting the contact pin and a connection terminal in a standard connection. A moveable means of the electrical connector electrically connects the contact pin and the connection terminal in a fault condition connection. The electrical connector also includes means for guiding the movable means relative to the fixed means from a first position to a second position to connect with the contact pin in the fault condition connection.
In yet another implementation, an electrical bushing is provided for connecting a power distribution component with a power line. The electrical bushing includes a connection terminal that is configured to electrically connect with the power distribution component. A socket of the electrical bushing is configured to provide a first current path between the connection terminal and a contact pin associated with the power line when the contact pin is inserted into the socket during a standard connection. The electrical bushing also includes a slider component that is configured to move relative to the socket to make contact with the contact pin and provide a second current path between the connection terminal and the contact pin during a fault condition connection. The first current path may be different than the second current path.
Other systems, methods, features and advantages will be, or will become, apparent to one with skill in the art upon examination of the following figures and detailed description. It is intended that all such additional systems, methods, features and advantages be included within this description, be within the scope of the invention, and be protected by the following claims.
An electrical connector may be used to connect multiple electrical devices. The electrical connector may include a socket that receives a contact pin associated with one of the electrical devices. When the contact pin is being inserted in the electrical connector, either a standard connection or a fault condition connection may occur. In a standard connection, the socket receives the contact pin and provides a long-term current path between the contact pin and an external device connected with the electrical connector. In a fault condition connection, there may be a problem somewhere in the system that may cause a much higher current flow and subsequent electric arc. The electrical connector includes a slider component that is able to move relative to the socket. In a fault condition connection, the slider component may move relative to the socket to make contact with the contact pin and extinguish possible electric arcs caused during the fault condition connection.
The electrical connector 102 may include a connection terminal 104, a core component 106, a socket 108, and a slider component 110. The socket 108 provides a primary current path between the connection terminal 104 and a contact pin inserted into the socket 108 during a standard connection. The slider component 110 may move relative to the socket 108 to make contact with the contact pin and provide a primary current path between the connection terminal 104 and the contact pin during a fault condition connection. The primary current path through the slider component 110 in the fault condition connection is different than the primary current path through the socket 108 in the standard connection. Also, the primary contact interface (e.g., the socket 108) between the electrical connector 102 and the contact pin in the standard connection is different than the primary contact interface (e.g., the slider component 110) between the electrical connector 102 and the contact pin in the fault condition connection. A fault condition connection may result when the contact pin is inserted into the electrical connector 102 and there is a problem in the system. The problem may cause a much higher current flow than experienced in the standard connection. The electrical connector 102 may serve as a fault current bushing that attempts to minimize harm caused during a fault condition connection.
The electrical connector 102 may be used to connect power distribution equipment, such as transformers, switch gear, power lines, or other electrical devices. The electrical connector 102 in one implementation may be a 15 kilovolt 200 amp switch with a gas actuated slider which provides a 10 kiloamp 10 cycle fault closure capability. In one implementation, the electrical connector 102 may be part of an underground residential 200 amp medium voltage distribution circuit. The voltage level experienced at the electrical connector 102 may be greater than 10 kilovolts. For example, the electrical connector 102 may experience voltage levels from about 15 kilovolts to about 35 kilovolts in some implementations. In other implementations, the electrical connector 102 may experience other voltage levels or may be part of another type of power distribution system.
The electrical connector 102 may connect a transformer (e.g., a padmount transformer) with a power line. The transformer may be a single phase transformer that includes one electrical connector like the electrical connector 102 as a first terminal and another electrical connector like the electrical connector 102 as a second terminal. In another implementation, the electrical connector 102 may be used with a three phase transformer that includes six electrical connectors like the electrical connector 102 as terminals.
The connection terminal 104 may connect with an external electrical device, such as a transformer, switch, or other power distribution component. The connection terminal 104 may serve as an interface between the external electrical device and the rest of the electrical connector 102. The connection terminal 104 may be formed of a conductive material. Current may flow between the external electrical device and the electrical connector 102 through the connection terminal 104. The connection terminal 104 may define an opening that accepts an electrical contact associated with the external electrical device. The opening may be threaded to receive a corresponding threaded electrical contact associated with the external electrical device.
The core component 106 may be electrically connected with the connection terminal 104. Current may flow between the connection terminal 104 and the core component 106. In one implementation, the core component 106 and the connection terminal 104 are separate components. In another implementation, the core component 106 and the connection terminal 104 are parts of one unitary component. For example, the connection terminal 104 may be the portion of the core component 106 that connects with an external electrical device, such as a power distribution component.
The core component 106 may also be electrically connected with the socket 108. Current may flow between the core component 106 and the socket 108. In one implementation, the core component 106 and the socket 108 are separate components. In another implementation, the core component 106 and the socket 108 are parts of one unitary component. For example, the socket 108 may be the portion of the core component 106 that connects with a contact pin, such as a contact pin associated with a power line.
The socket 108 may serve as an interface between the contact pin and the rest of the electrical connector 102. The socket 108 may be formed of a conductive material. Current may flow between the electrical connector 102 and the contact pin through the socket 108. The socket 108 may define an opening that accepts a contact pin associated with a power line.
When the contact pin is inserted into the electrical connector 102 and a standard connection results, the socket 108 mechanically and electrically connects with a conductive portion of the contact pin. When the contact pin is inserted into the electrical connector 102 and a fault condition connection results, the socket 108 may not mechanically connect with the conductive portion of the contact pin in some instances. The fault condition may prevent a lineman from inserting the contact pin all the way into the socket 108. For example, the expanding gas associated with an electric arc created in a fault condition may make it difficult to insert the contact pin into the socket 108.
The electric arc may be extinguished when a physical connection is made with the conductive portion of the contact pin. The socket 108 may be unable to move towards the contact pin to make the physical connection with the contact pin. For example, the socket 108 may be held in a fixed position relative to the core component 106 and the connection terminal 104. Therefore, the slider component 110 may be used to make a connection with the conductive portion of the contact pin to extinguish the electric arc. For example, the slider component 110 may move in a longitudinal direction relative to the socket 108 in response to occurrence of a fault condition to make physical contact with the contact pin. The increase in gas pressure caused by the electric arc may be used to propel the slider component 110 forward until the slider component 110 makes contact with the conductive portion of the contact pin. Therefore, the electrical connector 102 may serve as a fault current bushing that is configured to handle both standard connections and fault condition connections. The fault current bushing includes the socket 108 to make contact with the contact pin in a standard connection and the slider component 110 to make contact with the contact pin in the fault condition connection.
After the slider component 110 makes contact with the contact pin, the slider component 110 provides a current path between the contact pin and the connection terminal 104. Because the current flows through the slider component 110 in the fault condition connection, the current path provided in the fault condition connection is different than the current path provided during a standard connection. In the standard connection, the current generally flows through the socket 108 and does not substantially flow through the slider component 110.
In some implementations, the socket 108 remains in a substantially fixed position relative to the connection terminal 104 in a standard connection and a fault condition connection. Holding the socket 108 in a fixed position relative to the core component 106 and the connection terminal 104 may limit the number of contact interfaces required to maintain an electrical path between the socket 108 and the connection terminal 104. For example, in implementations where the socket 108 is free to move relative to the core component 106 and the connection terminal 104, one or more additional contact interfaces may need to be inserted into the current path to allow the movement of the socket 108.
The number of contact interfaces in the primary long-term current path may be minimized by holding the socket 108 in a fixed position and allowing the slider component 110 to move to make contact with the contact pin in fault condition connections. For example, the current path between an external device connected with the connection terminal 104 and the contact pin inserted into the socket 108 during the standard connection may consist of only two contact interfaces: (1) the contact interface between the external device and the connection terminal 104; and (2) the contact interface between the socket 108 and the contact pin. In some implementations, the current path between the connection terminal 104 and the socket 108 does not include any contact interfaces. For example, the socket 108 may be integrally connected with the connection terminal 104 as one unitary component. Other implementations may include additional contact interfaces allowing the socket 108 to move.
In fault condition connections, the current path between an external device connected with the connection terminal 104 and the contact pin may consist of three contact interfaces: (1) the contact interface between the external device and the connection terminal 104; (2) the contact interface between the core component 106 and the slider component 110; and (3) the contact interface between the slider component 110 and the contact pin.
The slider component 110 may include one or more electrical contacts 112 that make contact with the contact pin inserted into the electrical connector 102. In a fault condition connection, the electrical contacts 112 are used to make physical contact with a conductive portion of the contact pin to extinguish an electric arc created during a fault condition connection. When the slider component 110 is propelled forward, the electrical contacts 112 make the first connection with the conductive portion of the contact pin. After physical connection is made, the fault current will flow through the slider component 110 rather than through some other medium, such as air.
In a standard connection, the contacts 112 of the slider component 110 may serve another purpose. The contacts 112 may be positioned so that they extend past the socket 108 in a longitudinal direction, as shown in
The electrical connector 102 may include a guide component that guides the slider component 110 when the slider component 110 moves in a longitudinal direction during a fault condition connection. The guide component may guide the slider component 110 from a first position to a second position to connect with the contact pin in a fault condition connection. For example, the guide component may guide the slider component 110 from a position where the slider component 110 is fixed with the core component 106 to a position where the slider component 110 has connected with the conductive portion of the contact pin inserted into the electrical connector 102.
The guide component may be a protuberance/slot system. In one implementation, the slider component 110 includes a protuberance 202 and the core component 106 defines a slot 204, as shown in
The slot 204 may be an indentation, guide rail, or other channel. In one implementation, the slot 204 may be formed in the outer surface of the core component 106. In another implementation, the slot 204 may pass through to a hollow center of the core component 106. Alternatively, the slot 204 may be formed from one or more raised borders on the outer surface of the core component 106. The slot 204 and the core component 106 may be separate components that are joined together or may be parts of one unitary component. The protuberance 202 travels along the slot 204 when the slider component 110 moves relative to the core component 106 and the socket 108. The slot 204 includes an end portion that stops the movement of the slider component 110 when the protuberance 202 reaches the end portion of the slot 204.
The electrical connector 102 may also include a connection component 206. The connection component 206 restrains the slider component 110 from moving relative to the core component 106 and the socket 108 before occurrence of a fault condition. The connection component 206 may release the slider component 110 in response to a force created during a fault condition. After the connection component 206 releases the slider component 110, the slider component 110 is free to move relative to the core component 106 and the socket 108.
In one implementation, the connection component 206 may be a crimped connection between the core component 106 and the slider component 110. For example, a portion of the slider component 110 may be crimped to make contact with the core component 106. The core component 106 may define a recess 208 or other component to engage the slider component 110. In one implementation, the connection component 206 may be a protuberance/recess connection between the slider component 110 and the core component 106. The protuberance may stick out from the slider component 110, and the core component 106 may include a corresponding recess (e.g., the recess 208). Alternatively, the protuberance may extend from the core component 106 while the slider component 110 has the corresponding recess.
The connection component 206 may be designed so that the slider component 110 is held in place under standard connection conditions, but is released when a fault condition occurs. For example, the size and shape of the protuberance and recess may be designed to disengage upon experiencing a certain minimum force. The size and shape may be selected so that a minimum amount of force created by gas expansion in an electric arc fault current situation would disengage the slider component 110 from the core component 106. For example, the size and shape of the protuberance and recess may be selected so that they disengage in response to about 100 pounds of force. Other implementations may be designed to disengage in response to other amounts of force. The gas expansion force may then propel the slider component 110 in a longitudinal direction along the length of the electrical connector 102 to make contact with a contact pin.
The socket 302 may receive a contact pin and provide an electrical connection between the contact pin and a connection terminal, such as the connection terminal 104 of
The contact springs 304 may be shaped as cantilever spring fingers. One end of a cantilever spring finger may be connected to the body portion of the socket 302. The other end of the cantilever spring finger may be free to apply a force against the contact pin to maintain an electrical connection with the contact pin. In other implementations, the contact springs 304 may be designed in another configuration.
The contact springs may be formed from a conductive material (e.g., copper, a copper alloy such as tellurium copper, or another highly conductive material). Although these contact spring materials may be desirable for their conductive properties, they may also be susceptible to stress relaxation. Over time, the contact force provided by the contact springs 304 against the contact pin may diminish.
The helper springs 402 may be shaped as cantilever spring fingers. One end of the cantilever spring fingers may be connected to a support structure. The support structure may be a slider component 404, similar to the slider component 110 of
In one implementation, the helper springs 402 are formed from the same material as the contact springs 304. In another implementation, the helper springs 402 are formed from a different material than the contact springs 304. The helper springs 402 may be formed from a material that is more resistant to stress relaxation than the material used to form the contact springs 304. For example, if the contact springs 304 are formed from copper or a copper alloy, then the helper springs 402 may be formed from a material that does not include copper or a copper alloy. Other implementations may use copper or a copper alloy to form the helper springs 402. The helper springs may be formed from brass, phosphor copper, beryllium copper, steel, or another material.
In one implementation, one of the helper springs 402 abuts and applies a force to one of the contact springs 304. For example, there may be a one-to-one ratio between the helper springs 402 and the contact springs 304. In this implementation, each helper spring 402 may apply a force to a single contact spring 304. In another implementation, one helper spring 402 may apply a force to multiple contact springs 304. For example, each of the helper springs 402 may apply a force to the outer surface of two or more different contact springs 304, as shown in
In addition to the helper springs 402,
In a standard connection, the contact fingers 406 may serve another purpose. The contact fingers 406 may be positioned so that they extend past the socket 302 in a longitudinal direction. In a standard connection, the contact fingers 406 may serve as a preliminary point of electrical contact with the contact pin before the contact pin is fully inserted into the socket 302. As the contact pin is inserted into the electrical connector, the contact pin will reach the contact fingers 406 before reaching the contacts of the socket 302. During insertion of the contact pin, an electric arc may be formed even in a standard connection with normal current levels. Because the contact fingers 406 may serve as a preliminary point of contact with the contact pin before the contact pin reaches the socket 302, the contact fingers 406 may attract at least a portion of the electric arc from the contact pin. Therefore, the contact fingers 406 may be positioned to shield the socket 302 and the contact springs 304 from electric arc damage during connection of the contact pin with the socket 302 in a standard connection. In some implementations, the contact fingers 406 may not be a primary part of the long-term current path for the standard connection between the contact pin and the socket 302. Therefore, localizing the electric arc damage to the contact fingers 406 of the slider component 110 instead of the allowing the arc to damage the contact springs 304 of the socket 302 may result in a more reliable long-term connection through the electrical connector.
The radial interposer spring 708 may be compressed between the contact pin and the core component 704 when the contact pin is inserted into the socket 706. When the contact pin is inserted into the socket 706, the contact pin may exert a force on the radial interposer spring 708 that is orthogonal to the surface of the contact pin. Because the radial interposer spring 708 is compressed between the contact pin and the core component 704, the inner surface of the core component 704 will apply a response force to the radial interposer spring 708. The response force may be substantially equal in magnitude and substantially opposite in direction as compared to the force applied from the contact pin.
The radial interposer spring 708 may provide a large number of redundant connection points between the core component 704 and the contact pin. The radial interposer spring 708 may include twenty or more spring components that make contact with the contact pin when the pin is inserted into the socket 706. For example, the radial interposer spring 708 may include multiple slats 710 that are configured to make contact with the contact pin when the contact pin is inserted into the socket 706. The slats 710 may be strips of conductive material disposed between two support components. The support components may be used to connect the radial interposer spring 708 with the inner surface of the core component 704 while the slats 710 are used to make an electrical connection with the contact pin. The radial interposer spring 708 may define openings between each of the slats 710.
In one implementation, the radial interposer spring 708 may be a contact band formed into a substantially circular shape, such as the “Crown Band” sold by the Elcon Power Connector Products Division of Tyco Electronics Corporation or the “Louvertac Band” sold by Tyco Electronics Corporation. In another implementation, the radial interposer spring 708 may be a canted coil spring, such as the canted coil springs sold by the Bal Seal Engineering Company. In other implementations, other radial interposer contact springs or circumscribing radial springs may be used as the radial interposer spring 708.
Some implementations of the radial interposer spring 708, such as the crown band implementation, may include an hourglass-shaped contact band that is fit into the socket 706. For example, the radial interposer spring 708 may include a first end portion, a middle portion, and a second end portion. The two end portions may serve to connect the radial interposer spring 708 with the inner surface of the core component 704. The middle portion may be raised away from the inner surface of the core component to make contact with the contact pin when the pin is inserted into the socket 706. For example, the middle portion of the radial interposer spring 708 may have a smaller circumference than the two end portions of the radial interposer spring 708. Therefore, when the contact pin is inserted into the socket 706, the middle portion of the radial interposer spring 708 makes contact with the contact pin as the pin travels through the radial interposer spring 708. The contact pin will apply a force to the middle portion of the radial interposer spring 708. The force may be substantially orthogonal to the surface of the contact pin. In response, the core component 704 may apply a substantially equal and opposite force to the end portions of the radial interposer spring 708 that are in contact with the inner surface of the core component 704.
Some implementations of the radial interposer spring 708, such as the Louvertac implementation, may include louver slats that are bent about their longitudinal axes. The slats may be bent so that one edge of the slat is configured make contact with the contact pin when the contact pin is inserted into the socket. The other edge of the slat is configured to make contact with the inner surface of the core component 704. Therefore, the slats complete an electrical connection between the contact pin and the core component. The contact pin will apply a force to the louvered slats. The force may be substantially orthogonal to the surface of the contact pin.
The radial interposer spring 708 may be a contact band that is formed into a substantially cylindrical shape to fit within a substantially cylindrical opening in the socket 706 of the core component 704. For example, a strip of Louvertac contact material may be curled into a generally cylindrical shape so that one side of the strip abuts the inner surface of the core component 704 and the other side is ready to make electrical contact with a contact pin inserted into the socket 706. The substantially cylindrical shape may include shapes that are generally cylindrical, but have portions that deviate from a generally cylindrical shape. For example, an hour-glass shaped crown band may have a substantially cylindrical shape. A substantially cylindrical contact band may have a generally circular cross-sectional shape. The substantially circular/cylindrical contact band may be fit into the substantially circular/cylindrical opening in the socket 706. In one implementation, the circular/cylindrical contact band is formed into a substantially complete circle inside the socket 706. In other implementations, the circular/cylindrical contact band may only form a partial circle inside the socket 706. For example, the contact band may be formed into shape with a “C” cross-sectional shape.
The slats 710 of the radial interposer spring 708 may be spring elements. As a contact pin passes through the radial interposer spring 708, the slats 710 may compress or flex in response to physical contact from the contact pin. The slats 710 may then apply a reaction force against the contact pin to maintain an electrical connection between the core component 704 and the contact pin. In implementations of the radial interposer spring 708 that include an hourglass-shaped contact band (e.g., the crown band implementation), the middle portion of the contact band is compressed when the contact pin is inserted into the socket 706. Current may flow from the core component 704 to the end portions of the crown band that make contact with the core component 704, then to the middle portion of the crown band, and finally to the contact pin. In implementations of the radial interposer spring 708 that include one or more slats bent around their longitudinal axes (e.g., the Louvertac implementation), the slats may flex when the contact pin is inserted into the socket 706. Current may flow from the core component 704 to one edge of the slats, then to the other edge of the slats, and finally to the contact pin. Because of the large number of slats 710 in the radial interposer spring 708 that make contact with the contact pin, the radial interposer spring 708 may provide a great deal of redundancy to protect against electrical disconnection.
The electrical connector 102 of
While various embodiments of the invention have been described, it will be apparent to those of ordinary skill in the art that many more embodiments and implementations are possible within the scope of the invention. Accordingly, the invention is not to be restricted except in light of the attached claims and their equivalents.
This application is related to U.S. patent application Ser. No. ______ (Attorney Docket No. 12494/56), filed Feb. 24, 2009 and titled “Electrical Bushing with Helper Spring to Apply Force to Contact Spring,” and U.S. patent application Ser. No. ______ (Attorney Docket No. 12494/57), filed Feb. 24, 2009 and titled “Electrical Bushing with Radial Interposer Spring,” the entirety of each of which is hereby incorporated by reference.