EP3224910B1

EP3224910B1 - Underwater electrical connector

Info

Publication number: EP3224910B1
Application number: EP15825815.2A
Authority: EP
Inventors: Giorgio CACOPARDO; Mario Salvatore MUSUMECI; Riccardo PAPALEO
Original assignee: Dstec Srl
Current assignee: Dstec Srl
Priority date: 2014-11-25
Filing date: 2015-11-25
Publication date: 2018-12-19
Anticipated expiration: 2035-11-25
Also published as: WO2016084015A1; EP3224910A1; DK3224910T3

Description

The present invention relates in general to an electrical connector for use in underwater environment. More specifically, the present invention relates to an underwater electrical connector which is able to work with medium and high voltages (i.e. with voltages from 1 kV to more than 30 kV) and which also operable by means of a remotely-operated underwater vehicle, usually referred to with the acronym ROV (Remotely Operated Vehicle) or the acronym ROUV (Remotely Operated Underwater Vehicle).
Underwater electrical connectors operable by ROV were put on the market at the end of the 80's thanks to the idea of a US researcher, Mr. J. Cairnst of NURC (Nato Underwater Research Center) and became very soon a standard in the field of underwater electrical connections.
The underwater electrical connectors can be classified in two categories:

1) connectors having lower operating voltages (up to 10 kV), and
2) connectors having higher operating voltages (from 10 kV up to 30 kV).

The connectors belonging to this second category have the advantage that they operate with higher voltages, and therefore allow to reduce the cross-section areas of the underwater cables, thereby reducing the overall costs of the infrastructures, but the disadvantage that they have very large size and weight (with a length in the order of 10 m and a weight in the order of tons), thereby making their installation very difficult, and hence also expensive.
The known medium-voltage underwater electrical connectors use the so-called "oil filled" technology, in that they use special silicon-based oils to protect the chamber of the connector (hereinafter referred to as connection chamber), where the two male and female elements of the connector are electrically connected to each other, against the non-dielectric fluid normally present in the connection environment (typically sea water). The "oil filled" technology suffers however from the disadvantage that it requires the connection chamber to be filled up with oil after a given number of connection and disconnection operations, since each connection and disconnection operation entails a certain oil leakage. Therefore, these known medium-voltage underwater electrical connectors require periodic maintenance, which is also particularly difficult and expensive, since the connector to be filled up with oil must be temporarily removed and replaced with another connector in order to undergo the necessary maintenance operations.
An underwater electrical connector according to the preamble of independent claim 1 is known from US 2005/070141 .
It is an object of the present invention to provide a medium- and high-voltage underwater electrical connector which is able to operate even in case the connection chamber is filled with a non-dielectric fluid, for example sea water, normally present in the environment where the connector is installed and which does not therefore require to insulate the connection chamber by filling the same with oil. It is a further object of the present invention to provide an underwater electrical connector which has smaller size and weight than the prior art, for the same nominal operating voltage, thereby making installation of the connector easier and less expensive.
These and other objects are fully achieved according to the present invention by virtue of an underwater electrical connector having the features specified in the enclosed independent claim 1.
Advantageous embodiment of the invention are the subject-matter of the dependent claims, the content of which is to be regarded as forming an integral and integrating part of the following description.
In short, the invention is based on the idea of providing an underwater electrical connector according to claim 1, in which the female part has a seat which extends along an axial direction and is configured to receive the male part in a connection position, wherein the female part further comprises a first tubular body of electrically conductive material extending around said seat, coaxially thereto, for such a length that in the connection position the male part is wholly located inside the volume enclosed by the first tubular body, and wherein the female part further comprises a housing of electrically non-conductive material in which the first tubular body is embedded and said seat is defined. A distribution of the electrical field in the zone where the male and female parts are connected to each other is thus obtained which avoids generation of electrical discharges, even in presence of non-dielectric fluids inside the connector between the male and female parts, and therefore makes it possible for the connector to operate also with medium and high voltages.
Further characteristics and advantages of the present invention will result from the following detailed description, given purely by way of non-limiting example with reference to the appended drawings, where:

Figure 1 is an axial section view of an underwater electrical connector according to an embodiment of the present invention, in the connected condition;
Figure 2 is an axial section view of the male part of the connector of Figure 1;
Figure 3 is a side elevation view of the male part of the connector of Figure 1;
Figure 4 is an axial section view of the female part of the connector of Figure 1;
Figure 5 shows on an enlarged scale the detail A of Figure 2;
Figure 6 shows on an enlarged scale the detail B of Figure 2; and
Figure 7 shows on an enlarged scale the detail C of Figure 4.

With reference first to Figure 1, a medium- and high-voltage underwater electrical connector (i.e. an underwater electrical connector able to operate with nominal voltages from 1 kV to more than 30 kV), hereinafter simply referred to as connector, according to an embodiment of the present invention is generally indicated 10.
The connector 10 comprises a male part 12 and a female part 14. The male part 12 comprises a first electrical contact element 16 configured to be mechanically and electrically connected to a first conductor length (not shown, but of per-se-known type). Likewise, the female part 14 comprises a second electrical contact element 18 configured to be mechanically and electrically connected to a second conductor length (not shown, but of per-se-known type). The male part 12 is configured to be inserted into the female part 14 in a connection position (shown in Figure 1), where the first electrical contact element 16 is in contact with the second electrical contact element 18 and therefore the connector 10 ensures electrical connection between the first conductor length and the second conductor length.
With reference now also to Figures 2 and 3, the first electrical contact element 16 is made for example as a disc-shaped element and is mounted at an end (right-hand end, with respect to the point of view of a person looking at Figure 2) of a rod 20, to the opposite end of which (left-hand end, with respect to the point of view of a person looking at Figure 2) the first conductor length is directly or indirectly connectable. The first electrical contact element 16 and the rod 20 are obviously made of electrically conductive material, such as for example copper. In the illustrated embodiment, the first electrical contact element 16 and the rod 20 are advantageously made in one piece. The longitudinal axis of the rod 20 is indicated x. The direction of this axis will be hereinafter referred to as longitudinal or axial direction.
The male part 12 further comprises a housing 22, through which the rod 20 extends. The housing 22 comprises a first housing element 24 (or movable housing element), which is axially slidable relative to the rod 20, and therefore also relative to the first electrical contact element 16, and a second housing element 26 (or stationary housing element), which is secured to the rod 20. The first housing element 24 and the second housing element 26 are made of non-conductive material (for example polymeric material). The first housing element 24 comprises a head wall 28 and a sleeve 30. The head wall 28 extends transversely, i.e. perpendicular to the longitudinal axis x. The head wall 28 has a central through hole 31, having a diameter such that it accommodates the first electrical contact element 16, and a plurality of small through holes 32 distributed over a circumference of larger diameter than that of the central hole 31. The sleeve 30 comprises a plurality of frustoconical sectors 34 separated from each other by a reduced-thickness sleeve portion. The outer lateral surface of the sleeve 30 has therefore a given conicity. A plurality of radial through holes 36 are provided in the reduced-thickness sleeve portions comprised between each frustoconical sector 34 and the adjacent one. The first housing element 24 is axially movable between an extended position (Figures 2 and 3), corresponding to the disconnected condition of the connector 10, and a retracted position (Figure 1), corresponding to the connected condition of the connector 10. In the extended position of the first housing element 24 the first electrical contact element 16 is received in the central hole 31 of the head wall 28, while in the retracted position of the first housing element 24 the first electrical contact element 16 projects axially from the head wall 28.
The male part 12 further comprises a cylindrical membrane 38 interposed between the first housing element 24 and the rod 20. The cylindrical membrane 38 has an outer diameter substantially equal to the outer diameter of the first electrical contact element 16. In the illustrated embodiment the membrane 38 forms at a first end thereof, axially facing towards the first electrical contact element 16, a first annular portion 38a projecting radially inwards, and at a second, axially opposite end, i.e. at the end facing towards the second housing element 26, a second annular portion 38b projecting radially outwards. The membrane 38 is secured at a first end thereof to the first electrical contact element 16 by means of a first fixing ring 40 which is connected (for example by screws 42) to the first electrical contact element 16 and clamps the first annular portion 38a of the membrane 38 against the first electrical contact element 16. Likewise, the membrane 38 is secured at a second end thereof to the second housing element 26 by means of a second fixing ring 44 which is connected (for example by screws 46) to the second housing element 26 and clamps the second annular portion 38b of the membrane 38 against the second housing element 26. As is shown in the enlarged-scale view of Figure 5, the membrane 38 also forms a sealing lip 48 near the first annular portion 38a,.
The membrane 38 encloses, along with the first electrical contact element 16, the rod 20 and the first housing element 24, a compensation chamber 50 which is filled with oil. Preferably, a filler element 52 is also inserted between the rod 20 and the membrane 38 in order to reduce the amount of oil necessary to fill the compensation chamber 50. A spring 56 is received in an annular space 54 provided between the second housing element 26 and the membrane 38, which spring is made for example as a cylindrical helical spring and is configured to apply on the second housing element 26 an elastic force tending to keep this element in the aforesaid extended position.
When the male part 12 of the connector 10 is immersed in water, the annular space 54 is filled with water, as it is in communication with the surrounding environment via the radial through holes 36. The membrane 38 is therefore subject to a pressure from the outside tending to squash radially the same membrane, which pressure increases with depth.
In order to compensate for changes in the volume of the compensation chamber 50 due to pressure changes resulting from changes in the operating depth of the connector, a compensation device generally indicated 58 is associated to the compensation chamber 50. The compensation device 58 comprises first of all a compensation plunger 60, which in the illustrated embodiment is made as an annular plunger and closes a side (the side axially opposite to the one facing towards the first electrical contact element 16) of the compensation chamber 40. The compensation plunger 60 is subject to the pressure of the water where the male part 12 is immersed, the pressure of the water on the compensation plunger 60 tending to urge this plunger towards the first electrical contact element 16 and therefore to compress the oil contained in the compensation chamber 50. The compensation device 58 further comprises one or more actuation linkages 62 (two actuation linkages in the illustrated embodiment) arranged to urge the compensation plunger 60 towards the first electrical contact element 16, and therefore to produce an increase in the pressure of the oil in the compensation chamber 50, as a result of the movement of the first housing element 24 from the extended position to the retracted position. An example of actuation linkage 62 is shown on an enlarged scale in Figure 6 and comprises an oscillating lever 64 hinged at an intermediate point thereof to the second housing element 26. The first housing element 24 acts on the radially outer end (upper end, with respect to the point of view of a person looking at Figure 6) of the oscillating lever 64, while the radially inner end (lower end, with respect to the point of view of a person looking at Figure 6) of the oscillating lever 64 acts on a push rod 66 connected to the compensation plunger 60.
With reference now in particular to Figure 4, the second electrical contact element 18 of the female part 14 comprises an intermediate portion 68 having an axial through hole 70 which in the connected condition of the connector 10 (Figure 1) accommodates the first electrical contact element 16. The outer diameter of the first electrical contact element 16 is equal to or slightly larger than the inner diameter of the axial hole 70 of the second electrical contact element 18, whereby in the connected condition the outer lateral surface of the first electrical contact element 16 is in contact with the inner lateral surface of the axial hole 70 of the second electrical contact element 18 and electrical connection between the two electrical contact elements 16 and 18 is thus ensured. The second electrical contact element 18 further comprises a first tubular portion 72 which extends axially from the intermediate portion 68 towards a first end of the female part 14 (which end is axially facing, in the connected condition, towards the first conductor length) and in the connected condition accommodates the male part 12. The first tubular portion 72 has an axial extension (length) such that in the connected condition the male part 12 is wholly located inside this tubular portion. The second electrical contact element 18 further comprises a second tubular portion 74 which extends axially from the intermediate portion 68 towards a second end of the female part 14 axially opposite to the first one (i.e. facing, in the connected condition, towards the second conductor length). Although in the illustrated embodiment the first tubular portion 72 and the second tubular portion 74 are made in one piece with the intermediate portion 68 of the second electrical contact element 18, the first and/or the second tubular portions might be made as separate pieces with respect to the intermediate portion 68, provided they are electrically connected to the latter.
The second electrical contact element 18 of the female part 14 is embedded in a housing 76 of electrically non-conductive material (for example of polymeric material). The housing 76 forms, in the volume enclosed by the first tubular portion 72 of the second electrical contact element 18, a seat 78 adapted to receive the housing 22 of the male part 12. The seat 78 has a conical portion 78a with which the first housing element 24 of the male part 12 engages in the connected condition. The housing 76 also forms a cylindrical chamber 80 (hereinafter referred to as connection chamber) which extends in the longitudinal direction x and has a diameter equal to the inner diameter of the axial hole 70. The connection chamber 80 opens on one side into the seat 78, while it is closed on the opposite side. A plunger 82 is received in the connection chamber 80 so as to be axially slidable. A spring 84, made for example as a cylindrical helical spring, is received in the connection chamber 80 and applies on the plunger 82 an elastic force tending to urge this plunger towards an initial rest position (disconnected condition of the connector), where the face of the plunger facing towards the male part 12 is flush with a bottom wall 86 of the seat 78. The plunger 82 is provided with at least one first check valve 88 arranged to allow the fluid (sea water) to flow only in the direction from the seat 78 to the connection chamber 80 and with at least one second check valve 90 arranged to allow the fluid to flow only in the direction from the connection chamber 80 to the seat 78.
The above-described connector 10 operates as follows.
The male part 12 is inserted into the seat 78 of the female part 14 and urged axially towards the latter. While the head wall 28 of the first housing element 24 of the male part 12 stops when comes into abutment against the bottom wall 86 of the seat 78, the first electrical contact element 16 of the male part 12 penetrates into the connection chamber 80 until it is positioned inside the axial hole 70 of the second electrical contact element 18 of the female part 14. Also the membrane 38 penetrates (partially) into the connection chamber 80 along with the first electrical contact element 16 of the male part 12. The movement of the first housing element 24 of the male part 12 into the retracted position, due to the relative movement of the first electrical contact element 16, and of the second housing element 26 with it, with respect to the first housing element 24, brings about, via the actuation linkage(s) 62 of the compensation device 58, an increase in the pressure in the compensation chamber 50 of the male part 12 which tends to expand radially the membrane 38 and therefore ensures perfect seal of the membrane 38 with the inner cylindrical wall of the connection chamber 80. The connection chamber 80 is thus perfectly sealed off from the surrounding environment.
By virtue of the first tubular portion 72 of the second electrical contact element 18 of the female part 14 having an axially symmetric configuration with respect to the longitudinal axis x and having an axial extension such that it wholly encloses the male part 12 in the connected condition, the electrical field inside the volume enclosed by the first tubular portion 72, and hence also inside the connection region, has an axially symmetric distribution, in that it is constant all over this volume, for the same distance from the longitudinal axis x. Such a distribution of the electrical field in the region of connection between the male part 12 and the female part 14 of the connector 10 avoids generation of electrical discharges and therefore makes it possible for the connector to work even with very high nominal operating voltages, for example equal to or higher than 30 kV.
Naturally, the principle of the invention remaining unchanged, the embodiments and the constructional details may vary widely from those described and illustrated purely by way of non-limiting example, without thereby departing from the scope of the invention as defined in the appended claims.

Claims

Underwater electrical connector (10) for electrical connection between a first conductor length and a second conductor length in an underwater environment,
wherein the connector (10) comprises a male part (12) and a female part (14), the male part (12) comprising a first electrical contact element (16) arranged to be mechanically and electrically connected to the first conductor length and the female part (14) comprising a second electrical contact element (18) arranged to be mechanically and electrically connected to the second conductor length,
wherein the female part (14) has a seat (78) which extends along an axial direction (x) and is arranged to receive the male part (12) in a connection position such that the first electrical contact element (16) is in contact with the second electrical contact element (18), and wherein the female part (14) further comprises a housing (76) of electrically non-conductive material in which said seat (78) is defined,
characterized
in that the female part (14) further comprises a first tubular body (72) of electrically conductive material which is formed in one piece with the second electrical contact element (18), or at least is electrically connected to the latter, has an axially symmetric configuration with respect to the axial direction (x) and extends around said seat (78), coaxially thereto, for such a length that in the connection position the male part (12) is wholly located inside the volume enclosed by said first tubular body (72), and
in that the housing (76) of the female part (14) incorporates the first tubular body (72), whereby as a result of this configuration, the connector (10) is able to operate with medium and high voltages, even with the presence of non-dielectric fluids inside the connector (10) between the male part (12) and the female part (14).
Connector according to claim 1, wherein the male part (12) further comprises a housing (22) of electrically non-conductive material, which comprises in turn a first housing element (24) axially slidable relative to the first electrical contact element (16) and a second housing element (26) fixed relative to the first electrical contact element (16), the first housing element (24) being movable between an extended position, corresponding to the disconnected condition of the connector (10), in which the first electrical contact element (16) is enclosed by the first housing element (24), and a retracted position, corresponding to the connected condition of the connector (10), in which the first electrical contact element (16) projects axially from the first housing element (24), and wherein the male part (12) further comprises elastic means (56) for applying on the first housing element (24) an elastic force tending to keep said housing element in the extended position.
Connector according to claim 1 or claim 2, wherein the first electrical contact element (16) is made as a disc-shaped element and is mounted at an end of a rod (20) of electrically conductive material, at the opposite end of which the first conductor length is directly or indirectly connectable.
Connector according to claims 2 and 3, wherein the first housing element (24) comprises a head wall (28) and a sleeve (30), the head wall (28) extending perpendicular to the axial direction (x) and having a central through hole (31) of a diameter such that it accommodates the first electrical contact element (16), and the sleeve (30) having a frustoconical outer lateral surface.
Connector according to claim 3 or claim 4, wherein the male part (12) further comprises a cylindrical membrane (38) which is interposed between the first housing element (24) and the rod (20) and is secured at a first end thereof to the first electrical contact element (16).
Connector according to claim 5, wherein the first housing element (24) has openings (36) through which the cylindrical membrane (38) is in communication with the external environment and wherein the male part (12) further comprises pressure compensating means (58) for adjusting the pressure of a fluid contained in a compensation chamber (50) defined at least partially inside the cylindrical membrane (38) so as to compensate for pressure changes in the external environment.
Connector according to claim 5 or claim 6, wherein the female part (14) further has a cylindrical connection chamber (80) with a diameter substantially equal to the diameter of the first electrical contact element (16), which chamber extends in the axial direction (x) and opens at an end thereof into the seat (78), and wherein an intermediate part (70) of the connection chamber (80) is formed by the second electrical contact element (18) while the remaining part is formed by the housing (76) of the female part (14), whereby in the connected condition of the connector (10) the first electrical contact element (16) is received inside the connection chamber (80), in contact with said intermediate part (70) of the same, and the cylindrical membrane (38) is partially received inside the connection chamber (80).
Connector according to claims 6 and 7, wherein said pressure compensating means (58) are also arranged to produce an increase in the pressure of the fluid in the compensation chamber (50), tending to expand radially the cylindrical membrane (38), as a result of the movement of the first housing element (24) from the extended position to the retracted position.