Subsea electrical connector component

Abstract

A component of a subsea electrical connector, the component is made of an electrically insulating material. The component includes a protective coating applied to at least a portion of the electrically insulating material for preventing water permeation into the electrically insulating material, wherein the protective coating is a ceramic coating A method of manufacturing a component of a subsea electrical connector includes applying a protective coating to at least a portion of the electrically insulating material for preventing water permeation into the electrically insulating material, wherein the protective coating is a ceramic coating.

Claims

1. A method of manufacturing a component of a subsea electrical connector, comprising: providing the component of the subsea electrical connector, wherein the component is an insulating sleeve, the component being made of an electrically insulating material, applying a protective coating to at least a portion of the electrically insulating material for preventing water permeation into the electrically insulating material, wherein the protective coating comprises a ceramic coating; providing an inner conductive layer on at least one section of a radially inner surface of the insulating sleeve by plating the section of the radially inner surface or providing an interference fit between the conductive layer and the radially inner surface; wherein providing an interference fit between the conductive layer and the radially inner surface comprises: heating the insulating sleeve so that its diameter expands; inserting a tube made of a conductive material into the expanded diameter of the insulating sleeve; connecting the insulating sleeve to the tube by cooling down of the heated insulating sleeve, thus providing a fixed connection between the tube and the insulating sleeve, wherein the tube represents the inner conductive layer.

2. The method according to claim 1, wherein applying the protective coating comprises: repeated deposition of ceramic layers onto the electrically insulating material of the component in order to build up the ceramic coating.

3. The method according to claim 2, wherein the repeated deposition of ceramic layers is by thermal spraying or aerosol deposition.

4. A method of manufacturing a component of a subsea electrical connector, comprising: providing the component of the subsea electrical connector, wherein the component is an insulating sleeve, the component being made of an electrically insulating material, applying a protective coating to at least a portion of the electrically insulating material for preventing water permeation into the electrically insulating material, wherein the protective coating comprises a ceramic coating, providing an inner conductive layer on at least one section of a radially inner surface of the insulating sleeve by plating the section of the radially inner surface or providing an interference fit between the conductive layer and the radially inner surface, and providing, plating, or spraying, at least a second inner conductive layer on at least a further section of the radially inner surface of the insulating sleeve.

5. The method according to claim 4, wherein the second inner conductive layer comprises a metal layer or a conductive ceramic layer.

6. The method according to claim 4, wherein applying the protective coating comprises: repeated deposition of ceramic layers onto the electrically insulating material of the component in order to build up the ceramic coating.

7. The method according to claim 6, wherein the repeated deposition of ceramic layers is by thermal spraying or aerosol deposition.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The foregoing and other features and advantages of the invention will become further apparent from the following detailed description read in conjunction with the accompanying drawings. In the drawings, like reference numerals refer to like elements.

(2) FIG. 1 is a schematic drawing showing a sectional view of a subsea electrical connector including a component according to an embodiment of the invention.

(3) FIG. 2 is a schematic drawing showing a partly sectional view of a subsea connector including a component according to an embodiment of the invention.

(4) FIG. 3 is a flow diagram illustrating a method of manufacturing a component according to an embodiment of the invention.

DETAILED DESCRIPTION

(5) In the following, embodiments of the invention will be described in detail with reference to the accompanying drawings. It is to be understood that the following description of the embodiments is given only for the purpose of illustration and is not to be taken in a limiting sense.

(6) It should be noted that the drawings are to be regarded as being schematic representations only, and elements in the drawings are not necessarily to scale with each other. Rather, the representation of the various elements is chosen such that their function and general purpose become apparent to a person skilled in the art.

(7) FIG. 1 shows a sectional view of a subsea electrical connector 100 including a first subsea electrical connector part 101 and a complementary second subsea electrical connector part 102. In the embodiment shown in FIG. 1, the first connector part 101 is a receptacle part which is receiving the second connector part 102, which is a plug part. The first connector part 101 includes a support 12 from which a pin 10 extends in a forward direction. Pin 10 may also be termed receptacle pin since it is located inside the receptacle 17. The plug part 102 has a plug body 59 with a front surface 50 and a shuttle pin 60, which is pushed into the plug body 59 when the first and second connector parts 101, 102 are engaged and brought into the mated position. Mating occurs in the direction of the arrow illustrated in FIG. 1. During mating, the pin 10 enters the plug body 59 and pushes back the shuttle pin 60, which exposes a socket contact (not shown) which makes electrical contact with a contact portion 15 located in proximity to the tip of pin 10. The electrical conductor 11 provides electrical contact to the contact portion 15 inside the pin 10. The electrical conductor 11 is in particular a conductive core of the pin 10.

(8) Subsea electrical connector 100 is a wet-mateable subsea connector, in which the first and second connector parts 101, 102 can be engaged and disengaged at a subsea location. In an exemplary application, the subsea electrical connector 100 is deployed at a subsea location and is mated, whereafter it remains in the mated state for a prolonged period of time, e.g. several years, thus experiencing long term subsea exposure. Subsea connector 100 may be a high voltage subsea electrical connector for voltages in excess of 1.000 Volt, for example for voltages in the range between about 5.000 and about 80.000 Volt. In some embodiments, the subsea electrical connector 100 may comprise further pins 10, e.g. for providing further electrical connections or for providing a three-phase electrical connection.

(9) The first subsea electrical connector part 101 includes a component 20 which is made of an electrically insulating material, the electrically insulating material being a plastic material. It should be clear that other types of electrically insulating materials may be used in other embodiments. The component 20 provides the electrical insulation for the electrical conductor 11 of the pin 10. The component 20 may for example be an insulating sleeve provided around the electrical conductor 11 of pin 10. As can be seen from FIG. 1, the insulating sleeve extends forwardly from the support 12 along most of the pin's longitudinal extension.

(10) The component 20 comprises a protective coating 21. Protective coating 21 covers a portion of the outer surface of component 20, it covers in particular a portion of component 20 which is exposed to seawater when the first subsea electrical connector part 101 is deployed subsea. The protective coating 21 extends from a portion at which the outer surface of the protective coating 21 is sealed against the support 12 in a direction forwardly of the support. Accordingly, at the base of the pin 10, the plastic material of component 20 cannot come into contact with surrounding seawater.

(11) When the second subsea electrical connector part 102 is mated with the first connector part 101, the outer surface of a forward portion of pin 10 is sealed against the body 59. The protective coating 21 extends forwardly from the support 12 to a position which, when the first and second connector parts 101, 102 are mated, is located inside the plug body 59 behind such seal. Accordingly, when the subsea electrical connector 100 is in the mated position, the plastic material of component 20 is at the front portion of pin 10 also not exposed to surrounding sea water. The part of pin 10 which is exposed to sea water in the mated position of first and second connector parts 101, 102 is entirely covered by the protective coating 21. This way, the plastic material of component 20 can be protected from the surrounding sea water, Water permeation into the plastic material, for example through electrophoresis, can be prevented effectively by means of the protective coating 21.

(12) Protective coating 21 comprises or advantageously consists of a ceramic coating. By means of such ceramic coating, a high degree of resistance against corrosion can be achieved. Furthermore, the ceramic coating may be a conductive ceramic coating. The coating may be applied in such way that the bulk ceramic material of the coating is electrically conductive. The ceramic coating may furthermore be earthed, it may for example be connected to a ground or earth conductor. As an example, the support 12 or the housing of the receptacle part 101 of the subsea electrical connector 100 may be grounded or earthed, and the ceramic coating 21 may be connected thereto. The ceramic coating thus creates an earth screen which is in intimate contact with the plastic material of component 20. Accordingly, the electrical field generated by the current flowing through the electrical conductor 11 can be confined to within the electrical insulation provided by component 20, which plastic material can have a high break down strength. Furthermore, the component 20 has a controlled and uniform geometry, thereby avoiding high electrical stresses. In particular, high electrical stresses at the seals between pin 10 and support 12, or pin 10 and plug body 59 may be prevented by means of the conductive ceramic coating.

(13) The protective coating 21 which can consist of the ceramic coating can be applied by thermal spraying or by aerosol deposition. Examples include nitrogen plasma spraying, hydrogen plasma spraying, or high-velocity oxygen fuel (HVOF) spraying methods. Other spraying methods, which may for example using argon as a carrier gas may also be used. Ceramic powder for example TiO.sub.2 or Al.sub.2O.sub.3 having a small grain size may be used for thermal spraying. In order to obtain a conductive ceramic coating, the spraying parameters may be adjusted. As an example, the H.sub.2 concentration may be increased during plasma spraying or by using compressed air cooling during spraying. Cooling may for example prevent crack formation during spraying, thus increasing the conductivity of the ceramic coating.

(14) In particular, the coating may be applied to the component 20 as described in the publication Development of electrically conductive plasma sprayed coatings on glass ceramic substrates, Gadow, R.; Killinger, A.; Floristn, M.; Fontarnau, R.; Surface & Coatings Technology 205, Issue 4 (2010), 1021-1028, the contents of which is herein incorporated by reference in its entirety. By making use of the described methods and parameters, the conductivity and porosity of the ceramic coating may be adjusted as desired.

(15) When using aerosol deposition (AD) to apply the protective coating 21, a fine ceramic powder may be mixed with a carrier gas in an aerosol chamber and flown through a micro orifice nozzle for deposition on the component 20. A powder with a grain size between about 0.05 micrometer and about 1 micrometer may for example be employed. The aerosol deposition may for example be performed as described in Substrate heating effects on hardness of an a-Al2O3 thick film formed by aerosol deposition method, M. Lebedev et al., Journal of Crystal Growth 275 (2005) e1301-e1306, the contents of which is herein incorporated by reference in its entirety.

(16) The ceramic coating may be applied by a subsequent application of thin ceramic layers. The ceramic coating may thus be built up by ceramic layers applied on top of each other. Protection against permeation of surrounding seawater can thus be improved.

(17) The thickness of the ceramic coating and thus of the protective coating 21 may be between about 50 and about 200 micrometers, depending on the application and the desired coating properties. For thin coatings, coating thickness may for example be increased to increase protection against seawater permeation. A coating thickness of about 30 micrometer showed to be sufficient to achieve good protection against seawater permeation.

(18) After application of the ceramic coating, the coating may be post-machined or grounded, for example to a pre-defined thickness and to obtain the desired surface finish.

(19) In embodiments, the protective coating 21 consists only of the single ceramic layer. In other embodiments, it may comprise further layers, such as a bonding layer between the plastic material of component 20 and the ceramic layer, or a top layer, for example for further improving the resistance against seawater permeation.

(20) By means of the protective coating 21 in form of the ceramic coating, several advantages can be achieved. A hard wearing coating is obtained that resists impact, abrasion and the like. The coating is immune to corrosion, in particular immune to aqueous corrosion at the respective deployment temperatures. Furthermore, it is resistant to degradation from most types of chemical attack. Also, it can be used in a wide thermal range, the inventors have tested the coating from 60 degree Celsius to +230 degree Celsius. Also, the application of the ceramic coating by plasma spraying achieves a strong adhesion between the plastic material of component 20 and the ceramic coating. Further, a higher degree of control over uniformity and thickness is obtained. The ceramic coating further provides an effective thermal barrier to the substrate. Due to the reduction in processing chemicals, the coating is cost effective and has a smaller environmental impact compared to a plating solution. Also, by adjusting the process parameters, it is possible to produce conductive or non-conductive versions of the coating, so that the coating is very versatile.

(21) Optionally, the component 20 in form of the insulating sleeve may comprise an inner conductive layer (not shown) that is provided on at least one section of a radially inner surface of the insulating sleeve. The insulating sleeve has in some embodiments a through hole into which the electrical conductor 11 is inserted during assembly. The inner surface in this through hole can partly or completely be covered with the inner conductive layer. The conductive layer can be applied by plating of a metal layer. A layer of conductive plastic material, such as conductive PEEK may also be used. In the latter case, the component may be manufactured by providing a tube made of the conductive plastic material, heating the insulating sleeve, sliding the thus expanded insulating sleeve over the tube and letting the assembly cool to generate a interference fit. The inner portion of the tube may then be machined to correspond to the outer diameter of the electrical conductor 11.

(22) A filler may be provided between the insulating sleeve and the electrical conductor 11 in order to ensure good thermal conductivity. Furthermore, a good electrical connection can be established between the inner conductive layer and the electrical conductor 11 by means of an electrically conductive filler material, or some other component, such as the above described mediator.

(23) In other embodiments, the insulating sleeve may be formed by overmolding the electrically insulating plastic material over the electrical conductor 11.

(24) It should be clear that the component 20 may not only be implemented as an insulating sleeve for the electrical conductor 11, but may also be implemented in other portions of the subsea electrical connector 100. As an example, plastic material that is used at other portions of the first or second connector parts 101, 102 for electrical insulation or that is exposed to seawater might be provided with the ceramic coating and thus implement the component 20. Due to the good adhesion and the good mechanical properties of the ceramic coating, protection from surrounding sea water may also be provided to components of plastic material that are not used for electrical insulation or do not suffer from electrical stresses. A non-conductive ceramic coating may be used in these cases.

(25) FIG. 2 illustrates in more detail a particular embodiment of the subsea electrical connector 100 of FIG. 1. The explanations given above thus also apply to the embodiment of FIG. 2. As can be seen, the pin 10 is at its base portion wider than at the portion projecting forwardly from the support 12. The component 20, which is again the insulating sleeve of the pin 10, is provided with the protective coating 21, advantageously consisting of the ceramic coating, in a rear part of the pin 10. As can be seen, sealing is provided by O-rings 13 between the support 12 and the pin 10, in particular with the outer surface of the ceramic coating. FIG. 2 shows the first connector part 101 and the second connector part 102 in the mated position. The pin 10 has entered the plug body 59. The plug body 59 comprises the seal 51 which initially seals against the shuttle pin 60 and in the mated state illustrated in FIG. 2 seals against the pin 10. As can be seen, the protective coating 21 extends beyond the seal 51 into the plug body 59. Accordingly, the portion of component 20 that is not covered by the protective coating 21 is not exposed to seawater in the mated state which is illustrated in FIG. 2.

(26) In the rear part of the plug body 59, an incompressible fluid such as insulating oil 55 is provided.

(27) As can be seen in FIG. 2, there is a space or gap between the surface of support 12 from which the pin 10 projects, and the front surface 50 of the plug body 59. In the mated state of FIG. 2, seawater 30 is present in this space or gap. By means of the protective coating 21, it is ensured that only the protective coating 21 is exposed to the seawater 30, but not the plastic material of component 20.

(28) When electric current is present in the electrical conductor 11 (not illustrated in FIG. 2), electrophoresis may cause water molecules to permeate into the plastic material of component 20. If the ceramic coating is a conductive ceramic coating and is earthed, it shields the electrical field generated by the current so that the effect of electrophoresis is no longer present. Further, it provides a physical barrier to the seawater.

(29) FIG. 3 illustrates a method of manufacturing a component of a subsea electrical connector according to an embodiment of the invention. In step S1, a component of the subsea electrical connector is provided. The component is made of plastic material, in particular of PEEK. The component may for example be part of the electrical insulation of the connector, for example an insulating sleeve. In the optional step S2, areas of the component that are not to be coated are masked. Note that masking is only one option, and in other embodiments, the protective coating may simply be applied selectively to certain areas instead of masking, for example if the spraying process has a high enough spatial resolution.

(30) In step S3, the component is provided with a protective coating by applying by thermal spraying, in particular by plasma spraying, a layer of ceramic material directly onto the plastic material of the component. In step S4, further layers of ceramic material are applied by thermal spraying, thus building up a ceramic coating of desired thickness.

(31) In step S5, the ceramic coating is post-machined. This can be done to achieve a desired surface finish, or to achieve a desired coating thickness. After manufacturing the component, it may be assembled into the subsea electrical connector (optional step S6).

(32) It should be clear that modifications may be made to the method of manufacturing the component 20. As an example, further layers may be provided, such as an intermediate adhesive layer, or a top coating or the like or the ceramic coating may be applied by spraying only a single layer of ceramic material.

(33) While specific embodiments are disclosed herein, various changes and modifications can be made without departing from the scope of the invention. The present embodiments are to be considered in all respects as illustrated and non-restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.