The present invention relates generally to electrical cables and, in particular, to a connector and method for installing and supporting cables in generally vertical passageways.
Cables specifically designed for vertical applications typically feature tensile members that are used to lift the cable through a generally vertical passageway. An example of such a cable is presented in
Historically, cables such as the one illustrated in
When the cable, reaches the top of the generally vertical passageway, one tensile member is removed from the lifting hook and moved to the anchor point The process is repeated with each tensile member until all the cables are oil the hook/clevis and secured to the anchor location. This technique is applied under a number of different installation conditions including, but not limited to, the following:
1. With cables that have been clamped to the side of a shaft and arc therefore more or less already supported such that the top anchor serves simply as an additional safety factor.
2. After the cable has had temporary wooden clamps applied to support the weight of the cable during transfer.
3. Where the hooked tensile members are the only source of support for the weight of the cable.
There are two other methods of supporting a vertically installed cable. They are specific to the cable construction:
1. Steel wire armor applied to the outside of the cable has its own method of support and anchoring.
2. Cable supported using one or more messengers (tensile members) clamped to the outside of the cable along its length.
The method of transitioning the tensile members from the support rigging to the anchoring point suffers from the disadvantage that during the transition of tensile members, there are only two of the three (for example) tensile members supporting the cable. The third tensile member is unhooked and at this point does not support any of the load until it is re-established on the support structure.
In addition, transferring one tensile member at a time makes it very difficult to properly tension the tensile members so that when the installation is complete, the three tensile members share the load equally. The inequality in the tensions will either remain as such so that one member supports more load then the others, or in part the inequality will be compensated for by physical adjustments in the cable, such as the core unwrapping slightly around one of the tensile members and shifting of the tensile members so as to potentially damage the cable core.
Furthermore, there is a considerable amount of time spent doing the installation While the cable is “under tension.” The transfer takes up time and costly resources under critical conditions—when the cable is suspended—instead of doing “prep” work on the ground, when there is little risk and minimal resources in play.
Also, while the anchor design is the responsibility of the installation authority, cables supplied with “loops” are not designed by the installation authority and therefore open the possibility for installations that do not maintain the appropriate safety factor.
Finally, in the event that the cable needs to be removed, the prior art installation process needs to be repeated in reverse. This multiplies the disadvantages of the prior art process.
An embodiment of the connector of the invention, is indicated in general at 30 in
The battens are each provided with, a pin opening 42. The pin openings are aligned and sized to receive a king pin 44. One end of the king pin includes an enlarged head portion. The opposite end of the king pin may be enlarged to secure the king pin within the openings 42, or fasteners known in the art including, but not limited to, a pin, cap or nut may be used to secure the king pin through the battens. Alternatively, the king pin or other members may be integrally formed between the battens.
In order to use the connector 30, and in accordance with an embodiment of the method of the present invention, individual tensile members, indicated at 50 in
The connector can be custom designed. to address the weight of each cable installed and the end users requirement for an applied safety factor. Typically the cables are in the seventeen to eighteen thousand pound range and arc subject to a safety factor in the order of 5. As an example only, the connecter may be designed to support 100,000 lbs. Different standard sizes of the connector may be made for ranges of cable Weights and tensile member sizes.
In accordance with an embodiment of a method of the invention, the connection of the cable 52 to the connector 30 is done on the ground and is never disconnected. Once the tensile members 50 are in place between the battens of the connector (as illustrated in
The connector and the cable, as illustrated in
As illustrated in
As illustrated in FIGS. 5 and 6A-6C, when the top end of cable 52 reaches the top of the pull, the body 32 of the connector is moved into place against the central section 70 (
The above embodiment of the connector of the invention and associated method offers the following advantages:
1. Eliminates the need for transferring the tensile members and the associated risk of doing this under load.
2. Reduces the installation time when there are high-cost resources involved (crane, additional personnel etc).
3. Reduces risk exposure time.
4. Allows the tensile members to be installed in such a way that each member more or less takes an equal share of the load.
5. Ensures the safety factor is maintained by supplying the proper anchor bolts for the top end connector.
6. Allows for easy removal.
While the preferred embodiments of the invention have been shown and described, it will be apparent to those skilled in the art that changes and modifications may be made therein without departing from the spirit of the invention, the scope of which is defined by the appended claims.
This application claims priority to U.S. Provisional Patent Application No. 61/704996, tiled Sep. 24, 2012, the contents of which are hereby incorporated by reference:.
Number | Date | Country | |
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61704996 | Sep 2012 | US |