The present invention relates generally to cable connectors and terminators, more particularly, to connectors and terminators for flow-through cables.
Typical underground electrical cables include a number of copper or aluminum strands surrounded by a semiconducting or insulating strand shield, a layer of insulation, and an insulation shield. This design of underground cables is known for having a useful life of 25-40 years. In some instances, the life span of an underground cable is shortened when water enters the cable and forms micro-voids in the insulation. These micro-voids spread throughout insulation in a tree like shape, these collections of micro-voids are also called water trees.
Water trees are formed in the insulation when medium to high voltage alternating current is applied to a polymeric dielectric (insulator) in the presence of water and ions. As water trees grow, they compromise the dielectric properties of the polymer until the insulation fails. Many large water trees initiate at the site of an imperfection or a contaminant, but contamination is not a necessary condition for water trees to propagate.
Water tree growth can be eliminated or retarded by removing or minimizing the water or ions, or by reducing the voltage stress. Another approach requires the injection of dielectric enhancement fluid into interstices located between the strands of cables. Certain cables may include at least one dedicated conduit to aid the injection of a dielectric enhancement fluid into the interstices between the strands of cables. The fluid reacts with water inside the cable and oligomerizes to form a fluid with dielectric enhancement properties. The oligomerized fluid functions as a water tree retardant and provides other beneficial properties. Flow-through cables having a dedicated conduit to enhance the flow of the dielectric fluid through the length of the cable advance this injection technique.
Splicing and terminating flow-through cables is a difficult task. The use of these special cables is not widespread and conventional terminators do not offer effective solutions for connecting or terminating flow-through cables. One problem with using traditional cable connectors and terminators is the loss of the fluidic transfer capability when a connector clamps down on a conductive core. According to the present invention, fluidic transfer capability means having the capability to transfer both gas and liquid. In addition, traditional methods do not protect the conduits in the cable from contaminants during installation.
One example of a cable fluid injection sleeve that accommodates fluidic transfer in traditionally used cables is disclosed in the U.S. application Ser. No. 09/085,385, titled: Cable Fluid Injection Sleeve, the disclosure of which is hereby incorporated by reference. The subject matter disclosed in this reference offers several solutions for injecting fluidic material into a cable. However, this apparatus cannot be effectively used with a flow-through cable having one or more fluidic conduits. Like other terminators and connectors, this apparatus does not focus on the preservation of the fluid conduit opening at the end of the cable.
Therefore, as described above, a need exists for an efficient method to inject fluid into a flow-through cable. Moreover, devices and methods are needed to connect and terminate flow-through cables to preserve their fluidic transfer capability and to preserve the capability of injecting a fluidic material in a flow-through cable without having to disconnect the cable.
The present invention relates to methods and apparatuses for connecting flow-through cables. Flow-through cables have a conduit or a plurality of conduits longitudinally placed inside the cable to allow fluid passage. More specifically, the present invention provides several embodiments of joints and terminators for connecting and anchoring flow-through cables. The joints and terminators of the present invention provide electrical or optical communication in a conductor as well as a flow path that allows fluid to flow through the cable without leaking.
In one embodiment, a method for connecting two flow-through cables includes inserting a tubing material into the conduit of one flow-through cable, placing a crimp connector over the cable""s conductive core and crimping the crimp connector. The tubing material is then placed into the conduit of the second flow-through cable, the cables are aligned, and then the crimp connector is fastened to the conductive core of the second flow-through cable.
The termination assembly includes a rigid tubing material, a hollowed plug assembly that includes a single or a plurality of rigid tubes, a tubing connector connected to the single or plurality of rigid tubes, and a conductive terminator that has a cavity adapted to anchor a cable""s conductive core and allow a flexible tubing material to attach to the single or plurality of rigid tubes while being routed through the conductive terminator.
In another embodiment, the method for joining two flow-through cables includes the splicing method, as describe above, utilizing a two-part connector. In this method, the tubing material is inserted into the conduit of the first flow-through cable and then withdrawn from the first cable as it is fed into the joining flow-through cable. The two-part connector is fastened to the conductive cores either one piece at a time, or together after the two conductive cores are joined.
The present invention provides efficient solutions for injecting a dielectric enhancing substance into flow-through cables. Specifically, the devices and methods of the present invention allow an operator to achieve fluid and gas injections into flow-through cables without the need to remove the cable from an attached terminator or connector. The designs provide safe injection access to the cable conduit even while the cable is energized with an electrical charge. Further, the terminators and connectors of the present invention also allow for perpetual rejuvenation of the flow-through cables. A flow-through cable can be repeatedly or continuously injected over the lifetime of the cable.
The present invention provides several mechanisms that allow an operator to inject flow-through cables using a high injection pressure without a high risk of fluid or gas leakage. The design of the connectors and terminators allow the injection pressure to operate up to the maximum pressure of the flow-through cable conduit.
The present invention provides economical and efficient methods of cable connection and termination. The methods and devices in the present invention protect the conduit from contaminants during the installation. Further, the methods and devices of the present invention prevent the conduit from rupturing or collapsing.