Patent Application
20110092088
The present invention relates to electrical cable connectors, such as loadbreak connectors and deadbreak connectors.
Deadbreak cable connectors used in conjunction with 15, 25, and 35 Kilovolt (kV) switchgear generally include a power cable elbow connector having one end adapted for receiving a power cable and another end adapted for receiving a deadbreak bushing. The end adapted for receiving the bushing insert generally includes an elbow cuff for providing an interference fit with a molded flange on the bushing. This interference fit between the elbow cuff and the bushing insert provides a moisture and dust seal therebetween. Deadbreak elbows typically comprise a conductor surrounded by a semi-conducting layer and an insulating layer, all encased in a semiconductive outer shield.
To service or replace a deadbreak connector, power must be completely disconnected from the connector. In other words, the connector must be “dead” prior to introducing a “break” in the circuit by removing the connector or otherwise opening the ground associated with the device. If power is not disconnected, significant risk of shock or spark may occur. In some instances, for power to be disconnected from a deadbreak connector, an entire transformer must be powered off or otherwise disrupted, causing a disruption in any power equipment connected to the transformer.
Unlike deadbreak connectors, loadbreak connectors may be connected and disconnected without requiring a complete absence of underlying load. In other words, the connector may be under a “load” when introducing the “break.” Switchover from deadbreak connectors to loadbreak connectors, while otherwise advantageous, is a costly endeavor, typically requiring replacement of a significant portion of associated switchgear.
The following detailed description refers to the accompanying drawings. The same reference numbers in different drawings may identify the same or similar elements.
As shown in
Legacy deadbreak bushing 115 may include an axially extending, substantially conical body portion 122 having a first end 124 and a second end 126 provided distal from first end 124. Body portion 122 may be configured to include an axially extending central conductor 128 running therein for connecting a cable terminating element, such as an elbow connector, a tee-connector, an insulated cap, etc., from first end 124 and internal transformer switchgear to second end 126.
As illustrated in
In some implementations, exterior surfaces of switchgear elements, such as transformers, connectors, bushings, etc. may provide ground paths or connections for associated devices during operation. To ensure that no break is provided in this ground path during operation that could result in arcing or flashover occurrences, outer or exposed surfaces of deadbreak bushing 115 and any connected devices, such as elbow connectors, tee-connectors, splices, caps, etc., may also be formed of conductive or semiconductive materials, thereby providing unbroken ground paths. In one implementation, the outer exposed surface of deadbreak bushing 115 may be formed of conductive ethylene-propylene-diene monomer (EPDM) rubber or acrylonitrile butadiene rubber (NBR). Furthermore, consistent with these principles, mounting ring 130 and bailing tabs 132 may be formed of a conductive or semiconductive material, such as a metal, or an elastomer impregnated with conductive particles.
First end 124 of deadbreak bushing 115 may include a substantially cylindrical portion 136 configured to matingly engage a corresponding portion a deadbreak device, such as an elbow connector (not shown). Consistent with implementations described herein, first end 124 may also be configured to matingly receive a deadbreak end 138 of deadbreak-to-loadbreak bushing 110, as will be described in additional detail below.
Central conductor 128 may, in an area proximal to cylindrical portion 136 of first end 124, include a substantially tubular conductive region 139 (shown in dashed lines) for receiving therein an extending portion of a connected device, such as a conductor or stud extending from a cable termination end, such as an elbow, tee-connector, etc.
As illustrated in
Consistent with implementations described herein, the structure and devices attached to the transformer may be updated to loadbreak without requiring removal of the transformer or removing the deadbreak bushings installed therein. To enable this, deadbreak-to-loadbreak adapter bushing 110 may be configured to include a generally cylindrical body member 144 having a loadbreak end 146 and deadbreak end 138. In one exemplary implementation, body member 144 may be formed of conductive EPDM rubber. As shown, loadbreak end 146 may be configured to include a loadbreak bushing interface 147, such as an arc confining and extinguishing elements, connection elements for facilitating a connection to an elbow connector, etc. Loadbreak bushing interface 147 may be configured to receive thereon loadbreak devices, such as tee connectors, elbows, etc.
Deadbreak end 138 of deadbreak-to-loadbreak adapter bushing 110 may be configured to include a deadbreak bushing interface 150. For example, deadbreak bushing interface 150 may include a cavity 142 (shown in dashed lines) for receiving substantially cylindrical portion 136 of deadbreak bushing 115 upon connection of deadbreak-to-loadbreak adapter bushing 110 to deadbreak bushing 115. A conductor/stud 140 (shown in dashed lines) may project within cavity 142 toward deadbreak bushing 115. Upon assembly, conductor/stud 140 may be received within substantially tubular conductive region 139 of deadbreak bushing 115, thereby electrically connecting deadbreak-to-loadbreak adapter bushing 110 to deadbreak bushing 115.
Deadbreak-to-loadbreak adapter bushing 110 may include a shoulder region 148 formed between loadbreak end 146 and deadbreak end 138 that forms a substantially cylindrical flange about an intermediate portion of cylindrical body member 144. As illustrated in
Depending on the type of loadbreak equipment being used, different components and configurations may be included within deadbreak-to-loadbreak adapter bushing 110. For example, a 25 kV deadbreak-to-loadbreak adapter bushing 110 may be configured slightly differently than a 15 kV or 35 kV deadbreak-to-loadbreak adapter bushing 110. However, it should be understood that the differences in these configurations do not depart from the spirit and scope of the aspects described herein.
Deadbreak interfaces typically do not include provisions for holding them together, so it is necessary to secure deadbreak-to-loadbreak adapter bushing 110 to deadbreak bushing 115 prior to energizing the connection. To facilitate such securing, an adapter collar 154 may be provided for clampingly securing deadbreak-to-loadbreak adapter bushing 110 to deadbreak bushing 115 via a number of bailing rods 155. As illustrated in
Based on this configuration, when adapter collar 154 is placed over loadbreak end 146 of deadbreak-to-loadbreak adapter bushing 110, forward surface 158 of adapter collar 154 may abut rearward surface 152 of shoulder portion 148. An annular width Wc of adapter collar 154 may be sized such that an inner portion 162 of adapter collar 154 abuts shoulder portion 148 and a periphery 164 of adapter collar extends beyond the outside diameter of shoulder portion 148. That is, width Wc is larger than width Ws. In one exemplary implementation, annular width Wc (depicted in
As illustrated in
As depicted in
Although the present description refers to bailing rods 155 having opposing hooked and threaded ends, it should be understood that any suitable bailing element may be used, such as bailing straps or wires, clamps, a hub configuration, etc.
The above-described devices and configurations provide a low cost and effective mechanisms for converting a transformer or other switchgear from deadbreak to loadbreak. More specifically, deadbreak-to-loadbreak adapter bushing 110 may be easily and quickly installed on a legacy deadbreak bushing that is already affixed to the transformer.
The foregoing description of exemplary implementations provides illustration and description, but is not intended to be exhaustive or to limit the embodiments described herein to the precise form disclosed. Modifications and variations are possible in light of the above teachings or may be acquired from practice of the embodiments. For example, implementations may also be used for a number of loadbreak devices or families of devices.
Although the invention has been described in detail above, it is expressly understood that it will be apparent to persons skilled in the relevant art that the invention may be modified without departing from the spirit of the invention. Various changes of form, design, or arrangement may be made to the invention without departing from the spirit and scope of the invention. Therefore, the above-mentioned description is to be considered exemplary, rather than limiting, and the true scope of the invention is that defined in the following claims.
No element, act, or instruction used in the description of the present application should be construed as critical or essential to the invention unless explicitly described as such. Also, as used herein, the article “a” is intended to include one or more items. Further, the phrase “based on” is intended to mean “based, at least in part, on” unless explicitly stated otherwise.
This application claims priority under 35. U.S.C. §119, based on U.S. Provisional Patent Application No. 61/253,134 filed Oct. 20, 2009, the disclosure of which is hereby incorporated by reference herein.
| Number | Date | Country | |
|---|---|---|---|
| 61253134 | Oct 2009 | US |
