AC underwater power cable and cable water blocking performance detection method

Abstract

The invention relates to the technical field of underwater cable manufacturing and detection, in particular to an alternating-current underwater power cable and a cable water blocking performance detection method, and the alternating-current underwater power cable comprises a conductor, an insulating layer wrapping the conductor and a sheath wrapping the insulating layer. The conductor is formed by twisting a plurality of copper wires, and the copper wires are coated with PJ water-swelling water-blocking glue. The waterproof cable has the effect of enhancing the waterproof performance of the cable.

Description

Technical Field

[0001] The present application relates to the technical field of underwater cable manufacturing and testing, and in particular to an AC underwater power cable and a method for testing the water-blocking performance of the cable. Background Art

[0002] With the growing demand for underwater power transmission, cables are increasingly used underwater. However, although existing marine cables have taken certain water-blocking measures into consideration in their structural design, such as using water-blocking materials or adding water-blocking layers, these measures are often difficult to continue to function effectively during long-term underwater use. In addition, the current testing methods for cable water-blocking performance also have certain limitations, and it is impossible to fully and accurately evaluate the water-blocking ability of cables in actual use. Summary of the invention

[0003] In order to enhance the water-blocking performance of a cable and detect the water-blocking performance, the present application provides an AC underwater power cable and a method for detecting the water-blocking performance of the cable.

[0004] In a first aspect, the present application provides an AC underwater power cable, which adopts the following technical solution: An AC underwater power cable comprises a conductor, an insulating layer coated on the outside of the conductor and a sheath coated on the outside of the insulating layer. The conductor is formed by twisting a plurality of copper wires, and the copper wires are coated with PJ water-swellable water-blocking glue.

[0005] By adopting the above technical solution, the PJ water-swellable water-blocking adhesive expands when exposed to water and can prevent water from moving along the axial direction of the conductor between the conductor and the insulating layer.

[0006] Optionally, the insulating layer is formed by extrusion of cross-linked polyethylene.

[0007] By adopting the above technical solution, cross-linked polyethylene is polyethylene that is cross-linked between macromolecules under the action of high-energy rays (such as gamma rays, alpha rays, electron rays, etc.) or cross-linking agents, thereby greatly improving its mechanical properties, environmental stress cracking resistance, insulation performance and high temperature resistance. Its long-term working temperature can reach 90°C, and the instantaneous short-circuit temperature it can withstand can reach 170-250°C. The extrusion method can make the outer diameter of the insulation layer uniform, which is convenient for subsequent processing of grooves.

[0008] Optionally, a plurality of convex rings are provided on the annular surface of the insulating layer, and the convex rings are arranged at equal intervals along the extension direction of the insulating layer. A water-swellable waterstop ring is provided between two adjacent convex rings, and the outer diameter of the water-swellable waterstop ring is the same as the outer diameter of the convex ring.

[0009] By adopting the above technical solution, during normal working, the outer diameter of the water-swellable water-stop ring is the same as the outer diameter of the insulating layer, which can avoid squeezing the sheath wrapped outside the insulating layer. When an accident occurs and water enters, the water-swellable water-stop ring expands when it encounters water, thereby squeezing the sheath and the insulating layer, preventing water from moving axially between the sheath and the insulating layer along the insulating layer.

[0010] Optionally, the sheath is formed by extrusion of thermoplastic polyurethane elastomer.

[0011] By adopting the above technical solution, the thermoplastic polyurethane elastomer has good flexibility and wear resistance, which can protect the cable from damage by the external environment. At the same time, its excellent water resistance also helps to improve the water blocking effect of the cable. Since the sheath is on the outermost side of the entire cable, the extrusion processing method can effectively reduce the gaps that are difficult to avoid during wrapping.

[0012] Optionally, a rubber water-blocking tape is provided between the conductor and the insulating layer and between the insulating layer and the sheath.

[0013] By adopting the above technical solution, the rubber water-blocking tape can prevent water from flowing radially between the insulating layer and the sheath and between the conductor and the insulating layer.

[0014] In a second aspect, the present application provides a method for detecting the water blocking performance of a cable, which adopts the following technical solution: A method for detecting water blocking performance of a cable comprises the following steps: S1, thermal expansion simulation, power is supplied to the AC underwater power cable sample to heat the AC underwater power cable sample; S2, pressure simulation, after the thermal expansion simulation is completed, one end of the AC underwater power cable sample is sealed, and the other end is not processed, and then the AC underwater power cable sample is placed in a pressure vessel containing salt water to maintain pressure; S3, water blocking performance test. After the pressure simulation is completed, the AC underwater power cable sample is taken out of the pressure vessel, and the AC underwater power cable sample is cut into equal lengths starting from the unsealed end and numbered in sequence. The numbered cut samples are placed in a container with silicone oil exceeding 100°C in sequence, and it is observed and recorded whether there is a bursting sound when water boils or whether bubbles appear at the cut of the cut sample. When no bursting sound when water boils or bubbles appear at any of the cut samples, the number of the cut sample multiplied by the length of each cut sample is the water blocking performance of the AC underwater power cable.

[0015] By adopting the above technical solution, the water barrier capability of AC underwater power cables in actual use can be effectively evaluated. This method not only simulates the thermal expansion and pressure changes of cables in actual work, but also can intuitively judge whether water has entered the cable through the high-temperature silicone oil test, thereby accurately evaluating its water barrier performance.

[0016] Optionally, in S1, the power-on time of the thermal expansion simulation is 8 hours, and the cooling time is 16 hours, wherein within the 8 hours of power-on, the temperature of the AC underwater power cable sample should be maintained between 95°C and 100°C for at least two hours.

[0017] By adopting the above technical solution, the high temperature environment that the cable may encounter during actual use is simulated, allowing the cable material to fully expand, thereby more accurately evaluating its water-blocking performance.

[0018] Optionally, in S1, the AC underwater power cable sample should be subjected to at least three thermal expansion simulation pretreatments.

[0019] By adopting the above technical solution, multiple thermal expansion simulations can more comprehensively reflect the performance changes of the cable under different high temperature conditions and improve the accuracy and reliability of water-blocking performance detection.

[0020] Optionally, in S2, the pressure maintaining time is between 10 days and 15 days, the water pressure of the brine in the pressure vessel is 30 MPa, the salinity weight ratio of the brine is (31±2)% (31±2) g / kg, and the water temperature is maintained between 5°C and 35°C.

[0021] By adopting the above technical solution, the cable is subjected to pressure-maintaining test under long-term high pressure and temperature change conditions, which can simulate the complex stress state that the cable may encounter in the actual underwater environment, so as to more realistically evaluate its water-blocking performance. The salinity-to-weight ratio of the salt water is the salinity of my country's offshore, which is close to the actual use environment.

[0022] Optionally, in S3, the length of the cut sample is 10 mm.

[0023] By adopting the above technical solution, the cutting length of 10 mm can ensure that the state changes of each cutting sample can be accurately observed during the detection process, thereby improving the accuracy and efficiency of water-blocking performance detection.

[0024] In summary, the present application includes at least one of the following beneficial technical effects: 1. This application can reduce the length of water flowing along the conductor or between the insulation layer and the sheath after a cable fault occurs. When an AC underwater power cable is connected to a submersible seawater motor or other electrical equipment, it can reduce or avoid the risk of water entering the motor or other electrical equipment along the conductor or between the insulation layer and the sheath, thereby reducing or avoiding the impact range after a fault occurs; 2. Combining thermal expansion simulation, pressure simulation and precise segmentation detection steps, the water blocking ability of the cable in actual use can be comprehensively and accurately evaluated, providing a strong guarantee for the quality control and safe use of the cable. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a schematic diagram of the structure of an AC underwater power cable provided in an embodiment of the present application.

[0026] Explanation of the reference numerals: 1 - conductor; 2 - insulation layer; 201 - water-swellable water-stop ring; 3 - sheath; 4 - rubber water-blocking tape. DETAILED DESCRIPTION

[0027] The following is combined with Figure 1 This application is described in further detail.

[0028] An embodiment of the present application discloses an AC underwater power cable.

[0029] like Figure 1 As shown, the AC underwater power cable comprises a conductor 1, an insulating layer 2 and a sheath 3. The insulating layer 2 is formed by extruding a cross-linked polyethylene material and is coated on the outside of the conductor 1; while the sheath 3 is formed by extruding a thermoplastic polyurethane elastomer material and is wrapped on the outside of the insulating layer 2.

[0030] Cross-linked polyethylene forms a cross-linked structure between macromolecules under the action of high-energy rays (such as gamma rays, alpha rays, electron rays, etc.) or cross-linking agents, which significantly enhances its mechanical properties, environmental stress cracking resistance, insulation performance and high temperature resistance. It can work at a temperature of 90°C for a long time and can withstand an instantaneous short-circuit temperature of 170-250°C. The extrusion method can ensure the consistency of the outer diameter of the insulating layer 2, which is convenient for subsequent processing of grooves.

[0031] Thermoplastic polyurethane elastomer provides external protection for the cable with its excellent flexibility and wear resistance, avoiding damage from the external environment, and its excellent water resistance helps to improve the water blocking effect of the cable. Since the sheath 3 is located at the outermost layer of the cable, the extrusion processing method effectively reduces the inevitable gaps in the wrapping process.

[0032] like Figure 1As shown, specifically, the conductor 1 is twisted from a plurality of copper wires, and the copper wires are coated with PJ water-swellable water-blocking glue. A plurality of convex rings are arranged on the annular surface of the insulating layer 2, and the convex rings are arranged at equal intervals along the extension direction of the insulating layer 2. A water-swellable water-stopping ring 201 is arranged between any two adjacent convex rings, and the outer diameter of the water-swellable water-stopping ring 201 matches the outer diameter of the convex ring.

[0033] Under normal working conditions, the outer diameter of the water-swellable water-stop ring 201 is the same as the outer diameter of the convex ring, which avoids squeezing the outer sheath 3 of the insulating layer 2. Once water ingress occurs unexpectedly, the water-swellable water-stop ring 201 swells when exposed to water, thereby squeezing the sheath 3 and the insulating layer 2, and preventing water from moving between the sheath 3 and the insulating layer 2 along the axial direction of the insulating layer 2. At the same time, the PJ water-swellable water-blocking glue swells when exposed to water, which can prevent water from moving between the conductor 1 and the insulating layer 2 or between multiple copper wires of the conductor 1 along the axial direction of the conductor 1.

[0034] In order to prevent water from flowing radially between the insulating layer 2 and the sheath 3 and between the conductor 1 and the insulating layer 2 , a rubber water-blocking tape 4 may be provided between the conductor 1 and the insulating layer 2 and between the insulating layer 2 and the sheath 3 .

[0035] The implementation principle of an AC underwater power cable in the embodiment of the present application is as follows: when water ingress occurs unexpectedly, the water-swelling water-stop ring 201 swells when exposed to water, thereby squeezing the sheath 3 and the insulating layer 2, and preventing water from moving between the sheath 3 and the insulating layer 2 along the axial direction of the insulating layer 2. At the same time, the PJ water-swelling water-blocking glue swells when exposed to water, and can prevent water from moving between the conductor 1 and the insulating layer 2 or between multiple copper wires of the conductor 1 along the axial direction of the conductor 1. This reduces or avoids the risk of water entering the motor or other electrical appliances along the conductor 1 or between the insulating layer 2 and the sheath 3, thereby reducing or avoiding the impact range after the failure occurs.

[0036] The embodiment of the present application also discloses a method for detecting the water blocking performance of a cable.

[0037] The cable water blocking performance detection method comprises the following steps.

[0038] S1, thermal expansion simulation, power on the AC underwater power cable sample to heat the AC underwater power cable sample. The power-on time of thermal expansion simulation is 8 hours, and the cooling time is 16 hours. During the 8 hours of power-on, the temperature of the AC underwater power cable sample should be kept between 95℃ and 100℃ for at least two hours. The AC underwater power cable sample should undergo at least three pretreatments of thermal expansion simulation.

[0039] Thermal expansion simulation can simulate the high temperature environment that the cable may encounter during actual use, allowing the cable material to fully expand without contacting water, thereby more accurately evaluating its water-blocking performance.

[0040] S2, pressure simulation, after the thermal expansion simulation, one end of the AC underwater power cable sample is sealed, and the other end is not processed, and then the AC underwater power cable sample is placed in a pressure vessel containing salt water for pressure maintenance. The pressure maintenance time is between 10 days and 15 days, the water pressure of the salt water in the pressure vessel is 30MPa, the salinity weight ratio of the salt water is (31±2)% (31±2)g / kg, and the water temperature is maintained between 5℃-35℃.

[0041] Performing a pressure test on the cable under continuous high pressure and temperature fluctuations can simulate the complex stress conditions that the cable may encounter in the actual underwater environment, thereby more accurately evaluating its water barrier performance. The salinity-to-weight ratio of the salt water used matches the salinity of my country's offshore waters to ensure that the test environment is closer to actual application conditions.

[0042] S3, water-blocking performance test. After the pressure simulation is completed, the AC underwater power cable sample is taken out of the pressure vessel, and starting from the unsealed end, the AC underwater power cable sample is cut into equal lengths of 10 mm each, and numbered in sequence. The numbered cut samples are placed in a container with silicone oil exceeding 100°C in sequence, and it is observed and recorded whether there is a bursting sound when water boils or whether bubbles appear at the cut of the cut sample. When no bursting sound when water boils or bubbles appear at any of the cut samples, the number of the cut sample multiplied by the length of each cut sample is the water-blocking performance of the AC underwater power cable.

[0043] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. An AC underwater power cable, characterized in that: include: A conductor (1), an insulating layer (2) coated on the outside of the conductor (1), and a sheath (3) coated on the outside of the insulating layer (2); the conductor (1) is formed by twisting a plurality of copper wires, and the copper wires are coated with PJ water-swellable water-blocking glue.

2. The AC underwater power cable according to claim 1, characterized in that: The insulating layer (2) is formed by extrusion of cross-linked polyethylene.

3. The AC underwater power cable according to claim 2, characterized in that: A plurality of convex rings are provided on the annular surface of the insulating layer (2), and the convex rings are arranged at equal intervals along the extension direction of the insulating layer (2). A water-swellable water-stop ring (201) is provided between two adjacent convex rings, and the outer diameter of the water-swellable water-stop ring (201) is the same as the outer diameter of the convex ring.

4. The AC underwater power cable according to claim 1, characterized in that: The sheath (3) is formed by extrusion of thermoplastic polyurethane elastomer.

5. The AC underwater power cable according to claim 1, characterized in that: A rubber water-blocking tape (4) is provided between the conductor (1) and the insulating layer (2) and between the insulating layer (2) and the sheath (3).

6. A method for detecting water blocking performance of a cable, the method being applied to the AC underwater power cable according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, thermal expansion simulation, power is supplied to the AC underwater power cable sample to heat the AC underwater power cable sample; S2, pressure simulation, after the thermal expansion simulation is completed, one end of the AC underwater power cable sample is sealed, and the other end is not processed, and then the AC underwater power cable sample is placed in a pressure vessel containing salt water to maintain pressure; S3, water blocking performance test. After the pressure simulation is completed, the AC underwater power cable sample is taken out of the pressure vessel, and the AC underwater power cable sample is cut into equal lengths starting from the unsealed end and numbered in sequence. The numbered cut samples are placed in a container with silicone oil exceeding 100°C in sequence, and it is observed and recorded whether there is a bursting sound when water boils or whether bubbles appear at the cut of the cut sample. When no bursting sound when water boils or bubbles appear at any of the cut samples, the number of the cut sample multiplied by the length of each cut sample is the water blocking performance of the AC underwater power cable.

7. The cable water blocking performance detection method according to claim 6, characterized in that: In S1, the power-on time of the thermal expansion simulation is 8 hours, and the cooling time is 16 hours, wherein the temperature of the AC underwater power cable sample should be maintained between 95°C and 100°C for at least two hours within the 8 hours of power-on.

8. The cable water blocking performance detection method according to claim 7, characterized in that: In S1, the AC underwater power cable sample should be subjected to at least three thermal expansion simulation pretreatments.

9. The cable water blocking performance detection method according to claim 6, characterized in that: In S2, the pressure holding time is between 10 days and 15 days, the water pressure of the brine in the pressure vessel is 30 MPa, the salinity weight ratio of the brine is (31±2)% (31±2) g / kg, and the water temperature is maintained between 5°C and 35°C.

10. The cable water blocking performance detection method according to claim 6, characterized in that: In S3, the length of the cut sample is 10 mm.

Images