Apparatus for terminating and interconnecting rigid electrical cable and method

#This invention relates to electrical terminations and connectors used in power and information transmission systems. More specifically, the invention provides electrical terminations and connectors for substantially rigid cable and which hermetically seal the conductors therein from adverse environments.

#In applications where electrical equipment operates in adverse environments, it is important to protect the cable and the connectors which supply electrical energy and which communicate control signals with the equipment. It is not uncommon for the cable to be a multi-leg rigid cable having an armor jacket with each individual conductor therein insulated and protected by a further sheath. The jacket and the sheath can include a steel or other metal structure. The cable legs connect to the equipment or to other cables through connectors or by field splicing.

#Typical adverse environments occur, for example, in the reactor vessel of a nuclear reactor, in a deep underwater environment, and in an oil well. In these and like situations, it may be necessary that an electrical connector or an electrical penetrator through a pressure barrier transmits electrical power and/or control signals across the barrier and maintains an environmental separation between the different conditions on opposite sides of the barrier. The electrical cables, connectors and penetrators typically are subjected to temperatures and pressures that can vary over wide ranges. They can also be subjected to corrosive liquids and gases.

#For a fuller understanding of the nature and objects of the invention, reference is made to the following detailed description and the accompanying drawings, in which:

#FIG. 1 is a diagrammatic view of an oil well installation of a submersible pump and embodying one practice of the invention;

#FIGS. 1A and 1B are, respectively, enlarged cross-sectional details of the motor lead extension cable and of the submersible pump cable of FIG. 1;

#FIG. 1 shows an illustrative oil well in which a packer penetrator 100 employs cable terminations according to the invention. At the top of the well, above the earth's surface, is a fitting 110, commonly designated a "tree", for piping crude oil from the well. The tree 110 is mounted on a bonnet 112 seated on a wellhead 114. A well casing 116 extends downward from the wellhead 114 to the bottom of the well. The wellhead 114 can be at the surface of the earth or at the floor of the ocean, i.e. at the sea bed. Production tubing 118 within the casing 116 feeds pumped crude oil upward in the well and through the bonnet 112 to the tree 110. The wellhead 114 and the bonnet 112 form a pressure barrier between the environmental conditions above the earth's surface or sea bed, depending on the installation and at the interior of the well casing 116 at the top of the well. A packer 120 seated in the well casing 116 near the bottom of the well, and fitted with the packer penetrator 100, provides a pressure and environmental barrier between the well casing above it and below it. The production tubing 118 extends from the wellhead 114 through the packer 120 to an electric submersible pump 122. The illustrated installation includes, below and connected with the submersible pump 122, a conventional arrangement including a pump intake, a protector and submersible electric pump motor 124.

#As also shown in FIG. 1, a wellhead penetrator 126 at the top of the well couples electric power and control signals through the wellhead 114. An electric submersible pump (ESP) cable 128 extends within the casing 116 between the wellhead penetrator 126 and the packer penetrator 100, for transmitting electrical power. A motor lead extension cable 130 connects to the ESP cable 128 at the packer penetrator 100 and extends further downward within the casing 116 through a pothead flange body 127 to a connection lead 125 to the ESP motor 124. The series arrangement of electrical connections within the wellhead penetrator 126, through the ESP cable 128, within the packer penetrator 100, and through the motor lead extension cable 130 thus supply electrical operating power from above the well to the ESP motor 124 for operating the pump 122.

#The detail view in FIG. 1A shows that the illustrated motor lead extension cable 130 has a substantially rigid outer metal jacket 134, typically of stainless steel or galvanized armor steel, that encloses three cable legs 136. The illustrated motor lead extension cable 130 thus has a flat configuration with the individual legs 136 side by side; another has a circular cross section. Each illustrated cable leg 136 has a central electrical conductor 140 surrounded by an insulation layer 142 and a protective sheath 144. In a typical embodiment as illustrated, the central conductor 140 is a solid copper conductor, typically of number 2, 4 or 6 American wire gauge (AWG) size. The insulation 142 typically includes a layer of ethylene propylene diene methylene and can include a wrap of a high dielectric tape or polyimide film, one such material is marketed by the duPont Company under the trade designation Kapton. The outer sheath 144 of the cable leg 136 is preferably a seamless tube of a strong metal such as stainless steel or a nickel alloy. A motor lead extension cable 130 for practice of the invention and as illustrated in the detail of FIG. 1A is commercially available, including from Reda, A Camco Company, of Bartlesville, Okla., USA. The motor lead extension cable 130 preferably is manufactured and/or processed to diminish plastic deformation when subjected to thermal cycling.