A power cable insulation on-line repair terminal adapter and its application method

Abstract

The application discloses an on-line repair terminal adapter for power cable insulation and an application method thereof. In the adapter, an insulation shell has a cavity, and the insulation shell has a power-on channel, a liquid injection channel and a connecting channel which are communicated with the cavity respectively. A power switch conductor is installed in the cavity. An insulation wire passes through the power-on channel and is in sealed connection with the inner wall of the power-on channel, and the insulation wire is in electrical connection with the power switch conductor. A pneumatic valve is installed at the liquid injection channel. A connecting conductor is in electrical connection with the cable core of the power cable to be repaired, passes through the connecting channel, and is in electrical connection with the power switch conductor. An insulation sleeve is sleeved on the outside of the power cable to be repaired and is in sealed connection with the outer wall of the power cable to be repaired, and the insulation sleeve is communicated with the connecting channel and is in sealed connection with the outer peripheral wall of the connecting channel. The adapter of the application realizes on-line repair of the insulation of the aged power cable.

Description

Technical Field

[0001] The present application relates to the field of cable repair, and in particular to a power cable insulation online repair terminal adapter and an application method thereof. Background Art

[0002] Currently, my country's low- and medium-voltage cross-linked polyethylene (XLPE) insulated power cables with a service life of more than 20 years have exceeded 300,000 kilometers. These cables are experiencing severe insulation aging, leading to a high incidence of failures. However, replacing all these aging cables would require an investment exceeding tens of billions of RMB. Therefore, cable insulation repair technology is an important solution. This technology can improve the insulation level of existing cables and extend their service life by repairing water trees at a limited cost, thus offering significant economic value and practical significance.

[0003] Cable insulation repair technologies include traditional pressure injection cable repair and live repair. Traditional pressure injection cable repair relies on applying air pressure to diffuse a silicone repair fluid through the insulation layer. In areas containing water tree defects, the siloxane undergoes a hydrolysis-condensation reaction under the action of a catalyst, consuming water while generating an organic polymer with dielectric properties similar to those of cross-linked polyethylene. This polymer then fills the water tree pores, improving the electric field distribution in the water tree area, repairing the cable insulation and extending its service life. However, traditional injection repair techniques can result in insufficient effective concentration of the repair fluid in the water tree area, and the migration rates of different components in the repair fluid vary, making the overall repair reaction process inefficient. However, the direct cause of cable insulation performance is the random presence of defects in the insulation. Traditional repair techniques can result in insufficient concentration of the repair fluid at the defect location requiring efficient repair due to uneven diffusion. This limits the large-scale application of water tree repair technology. The live repair technology applies an external electric field during pressure injection, creating an electric field distortion zone in the water tree region. Polar molecules in the repair fluid, driven by dielectrophoretic forces and external air pressure, migrate toward the water tree region. Furthermore, the applied electric field opens the water tree channels, promoting the accumulation of the repair fluid in the water tree region, increasing its effective concentration and enhancing the repair effect. However, existing cable terminal adapters cannot simultaneously perform the cable powering and pressure injection and diffusion of the repair fluid. Summary of the Invention

[0004] The present application provides a power cable insulation online repair terminal adapter and an application method thereof, which can simultaneously perform the cable powering and the pressure injection-diffusion process of the repair fluid.

[0005] An embodiment of the present application provides an online repair terminal adapter for the insulation of a power cable, comprising an insulating housing, a power switch conductor, an insulating wire, a pneumatic valve, a connecting conductor, and an insulating sleeve. The insulating housing has a cavity, and the insulating housing has a power supply channel, a liquid injection channel, and a connecting channel, each of which is connected to the cavity. The power switch conductor is installed in the cavity. The insulating wire passes through the power supply channel and is sealed to the inner wall of the power supply channel, and the insulating wire is electrically connected to the power switch conductor. The pneumatic valve is installed at the liquid injection channel. The connecting conductor is electrically connected to the cable core of the power cable to be repaired, and the connecting conductor passes through the connecting channel and is electrically connected to the power switch conductor. The insulating sleeve is sleeved on the outside of the power cable to be repaired and is sealed to the outer wall of the power cable to be repaired, and the insulating sleeve is connected to the connecting channel and is sealed to the outer peripheral wall of the connecting channel.

[0006] In some embodiments, the power cable insulation in-line repair terminal adapter further includes a power switch conductor insulation base and a connecting rod. The power switch conductor insulation base has a mounting channel, a first end of which is for inserting the power switch conductor, and a second end of which is for inserting the insulated conductor and sealingly connected to the outer wall of the insulated conductor. The connecting rod includes two connecting rods, one supported on either side of the power switch conductor insulation base, and securely connects the power switch conductor insulation base to the insulating housing.

[0007] In some embodiments, the power switch conductor has an insertion channel for inserting the insulated wire. The power switch conductor also has two spring clips. The gap between the two spring clips is for inserting the connecting conductor. The two spring clips clamp and fix the connecting conductor.

[0008] In some embodiments, a first insulating sealant is filled between the insulated wire and the inner wall of the electrification channel, and a second insulating sealant is filled between the outer wall of the connecting channel and the insulating sleeve.

[0009] In some embodiments, a third insulating sealant is respectively filled between the insulated wire and the inner wall of the installation channel.

[0010] In some embodiments, an insulating waterproof layer is wrapped around the outer semiconductive layer of the power cable to be repaired. The insulating waterproof layer is sleeved inside the insulating sleeve along with the power cable to be repaired and fits the inner wall of the insulating sleeve.

[0011] In some embodiments, the power cable insulation online repair terminal adapter also includes two throat hoops, both of which are clamped on the outside of the insulating sleeve, and one throat hoop is clamped at the sealed connection between the insulating sleeve and the connecting channel, and the other throat hoop is clamped at the sealed connection between the insulating sleeve and the power cable to be repaired.

[0012] An embodiment of the present application also provides a power cable online repair device, comprising the aforementioned power cable insulation online repair terminal adapter, a fluid reservoir, an air compressor, a high-voltage power supply, a power cable to be repaired, a rear-end adapter, a rear-end adapter outlet valve, and a residual fluid tank. The fluid reservoir is connected to the pneumatic valve. The air compressor is connected to the fluid reservoir. The high-voltage power supply is connected to the insulated conductor. The first end of the power cable to be repaired is connected to a connecting conductor and an insulating sleeve, respectively. The rear-end adapter is connected to the second end of the power cable to be repaired. The rear-end adapter outlet valve is connected to the rear-end adapter. The residual fluid tank is connected to the adapter outlet valve.

[0013] The embodiment of the present application also provides an application method of the above-mentioned power cable insulation online repair terminal adapter, comprising the following steps: connecting an air compressor, a liquid storage tank, and a pneumatic valve in sequence, connecting a high-voltage power supply to an insulated wire, connecting the first end of the power cable to be repaired to the connecting conductor and the insulating sleeve respectively, and connecting the second end of the power cable to be repaired, the rear-end adapter, the rear-end adapter outlet valve, and the residual liquid tank in sequence. The power cable repair liquid in the liquid storage tank is injected into the insulating shell through the injection channel at a preset pressure. After the power cable repair liquid overflows from the outlet of the rear-end adapter, the rear-end adapter outlet valve and the pneumatic valve are closed. At the same time, the high-voltage power supply is turned on and industrial frequency alternating current is applied to the cable core of the power cable to be repaired. The pressure and voltage are maintained for a preset time so that the power cable repair liquid fully penetrates the defective position of the insulation layer of the power cable to be repaired to undergo a hydrolysis and condensation reaction, and then the high-voltage power supply is turned off. The pneumatic valve and the adapter outlet valve are opened, and the remaining power cable repair liquid and the waste liquid generated by the hydrolysis and condensation reaction are discharged from the pneumatic valve and the adapter outlet valve, and the power cable repair is completed.

[0014] In some embodiments, before the air compressor, the liquid storage tank, and the pneumatic valve are sequentially connected, the insulation level of the power cable to be repaired is evaluated and the conditions of the related equipment required for the repair are checked.

[0015] According to an embodiment of the present application, a terminal adapter for online repair of power cable insulation is provided, comprising an insulating housing, a power switch conductor, an insulated wire, a pneumatic valve, a connecting conductor, and an insulating sleeve. The insulating housing has a cavity, and has a power supply channel, a liquid injection channel, and a connecting channel, each of which is connected to the cavity. The power switch conductor is installed in the cavity. The insulated wire passes through the power supply channel and is sealed to the inner wall of the power supply channel, and is electrically connected to the power switch conductor. The pneumatic valve is installed in the liquid injection channel. The connecting conductor is electrically connected to the cable core of the power cable to be repaired, and the connecting conductor passes through the connecting channel and is electrically connected to the power switch conductor. The insulating sleeve is mounted on the outside of the power cable to be repaired and is sealed to the outer wall of the power cable to be repaired. The insulating sleeve is connected to the connecting channel and is sealed to the outer peripheral wall of the connecting channel. The power cable insulation online repair terminal adapter of this application, by providing both an energizing channel and a liquid injection channel, enables simultaneous cable energization and pressure injection and diffusion of the repair liquid. The two processes are separated and independently operated, making them easy to use while avoiding potential electrical hazards. This allows for online repair of aging power cable insulation without affecting the normal operation of the power cable. Furthermore, the power cable insulation online repair terminal adapter of this application is easy to install and remove, meeting the operational requirements of short-term on-site power outage repairs and possessing greater practical engineering application value. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 This is a structural diagram of a power cable insulation online repair terminal adapter in an embodiment of the present application;

[0018] Figure 2 This is a schematic diagram of the connection structure of the connecting conductor, the insulated wire and the power switch conductor in the embodiment of the present application;

[0019] Figure 3 This is a schematic structural diagram of a power cable online repair device according to an embodiment of the present application;

[0020] Figure 4 is a schematic diagram of a conventional injection repair device;

[0021] Figure 5 The loss factor test results of the cables in the two repair experiments. DETAILED DESCRIPTION

[0022] In order to make the purpose, technical solutions and advantages of this application more clearly understood, the present application is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the embodiments described herein are only used to explain this application and are not intended to limit this application.

[0023] The existing cable terminal adapter technology is not yet mature, and it is not possible to achieve the simultaneous injection of repair liquid pressure and cable operation. The existing adapter technology is difficult to apply to the rapid repair of large-section and long-distance power cables, and the repair effect is poor. Figure 1-2 An embodiment of the present application provides a power cable insulation online repair terminal adapter 1, including an insulating shell 101, a power switch conductor 102, an insulated wire 103, a pneumatic valve 104, a connecting conductor 105, an insulating sleeve 106, a power switch conductor insulating base 107, a connecting rod 108 and a throat clamp 109.

[0024] The insulating shell 101 has a cavity. The insulating shell 101 has a preset length. The insulating shell 101 has a power supply channel 1011 and a liquid injection channel 1012 on the first side in the longitudinal direction, which are respectively connected to the cavity. The power supply channel 1011 and the liquid injection channel 1012 are symmetrically arranged on the above-mentioned first side. The voltage is applied to the cable core 201 of the power cable 2 through the power supply channel 1011, and the power cable repair liquid is injected into the insulating shell 101 through the liquid injection channel 1012 to achieve live repair of the insulation of the power cable 2. The insulating shell 101 has a connecting channel 1013 on the second side in the longitudinal direction. The connecting channel 1013 is arranged at the center position of the above-mentioned second side. The insulating shell 101 is made of modified nylon PA66 material.

[0025] The power switch conductor 102 is specifically a power switch spring piece, which is installed in the cavity.

[0026] Insulated wire 103 is specifically an enameled wire. It is inserted into power supply channel 1011. A sealed connection is established between insulated wire 103 and the inner wall of power supply channel 1011. To achieve this, a first insulating sealant 110 is filled between insulated wire 103 and the inner wall of power supply channel 1011 to achieve this sealed connection. This first insulating sealant 110 is specifically a PMMA-specific plastic adhesive. The filling length of first insulating sealant 110 is 5 cm. Furthermore, insulated wire 103 is electrically connected to power switch conductor 102. To achieve this, power switch conductor 102 has an insertion channel 1021 into which insulated wire 103 is inserted to achieve this electrical connection.

[0027] The pneumatic valve 104 is specifically a BUC pneumatic quick-connect valve. The pneumatic valve 104 is installed at the injection channel 1012 and is used to control the on-off of the injection channel 1012.

[0028] The connecting conductor 105 is specifically a copper lug. One end of the connecting conductor 105 is electrically connected to the cable core 201 of the power cable 2 to be repaired. Furthermore, the connecting conductor 105 is inserted through the connecting channel 1013. The other end of the connecting conductor 105 is electrically connected to the power switch conductor 102. To this end, the power switch conductor 102 also has two spring clips 1022. The gap between the two spring clips 1022 allows the connecting conductor 105 to be inserted. The two spring clips 1022 clamp the connecting conductor 105 in place, achieving the aforementioned electrical connection and ensuring good electrical contact.

[0029] The insulating sleeve 106 is specifically a bellows. The insulating sleeve 106 is sleeved on the outside of the power cable 2 to be repaired. The insulating sleeve 106 is sealed to the outer wall of the power cable 2 to be repaired. To this end, an insulating waterproof layer 113 is wrapped around the outside of the outer semi-conductive layer 202 of the power cable 2 to be repaired. The insulating waterproof layer 113 is sleeved on the inside of the insulating sleeve 106 along with the power cable 2 to be repaired and adheres to the inner wall of the insulating sleeve 106 to achieve the above-mentioned sealed connection. The above-mentioned insulating waterproof layer 113 is specifically an insulating waterproof self-adhesive tape layer. The thickness of the insulating waterproof layer 113 is 2 mm and the length is 8 cm. The insulating sleeve 106 is connected to the connecting channel 1013 and is sealed to the outer peripheral wall of the connecting channel 1013. To this end, a second insulating sealant 111 is respectively filled between the outer wall of the connecting channel 1013 and the insulating sleeve 106 to achieve the above-mentioned sealed connection. The above-mentioned second insulating sealant 111 is specifically a special PMMA plastic glue. The filling length of the second insulating sealant 111 is 2.5 cm.

[0030] The power switch conductor insulating base 107 has a mounting channel. The first end of the mounting channel is for inserting the power switch conductor 102. The second end of the mounting channel is for inserting the insulated wire 103. The mounting channel is sealed to the outer wall of the insulated wire 103. To achieve this, a third insulating sealant 112 is filled between the insulated wire 103 and the inner wall of the mounting channel to achieve this sealed connection. This third insulating sealant 112 is specifically a PMMA-grade plastic adhesive. The filling length of the third insulating sealant 112 is 3 cm. Furthermore, the power switch conductor insulating base 107 is made of modified nylon PA66.

[0031] There are two connecting rods 108. They are supported on either side of the power switch conductor insulating base 107. They securely connect the power switch conductor insulating base 107 to the insulating housing. Both connecting rods 108 are made of modified nylon PA66. They are connected to the insulating housing 101 and the power switch conductor insulating base 107 using a hot melt connection.

[0032] There are two throat clamps 109. Both throat clamps 109 are clamped on the outside of the insulating sleeve 106. One throat clamp 109 is clamped on the sealed connection between the insulating sleeve 106 and the connecting channel 1013. The other throat clamp 109 is clamped on the sealed connection between the insulating sleeve 106 and the power cable 2 to be repaired.

[0033] Using the power cable insulation online repair terminal adapter 1 provided in this application to repair an aged power cable 2 has the following outstanding advantages:

[0034] 1. While applying voltage to the aged power cable 2, the power cable repair liquid is pressure-injected for repair. Under the action of the external electric field, the power cable repair liquid is directed to migrate toward the water tree area due to the dielectrophoretic force, thereby increasing the content of the power cable repair liquid in the water tree area and promoting the forward hydrolysis and condensation reaction. The water tree repair effect is better, and the insulation performance of the aged cable 2 is effectively improved.

[0035] 2. The insulating sealant and waterproof layer 113 ensure excellent airtightness in the adapter. The connection between the power switch conductor 102 and the connecting conductor 105 ensures the safety and effectiveness of the live cable insulation repair process. This design, with its easy installation and removal, can be used for both laboratory and field applications to repair the insulation of aged cables.

[0036] 3. The power cable insulation online repair terminal adapter 1 provided in the present application realizes the simultaneous application of the electric field and pressure injection processes through the power-on channel 1011 and the injection channel 1012. The two parts of the device are separated independently and are easy to use. At the same time, potential electrical hazards are avoided. It can realize online repair of the insulation of the aged power cable 2 without affecting the normal operation of the power cable 2, filling the technical gap in the live repair of the terminal insulation of the general power cable 2.

[0037] In addition, the use of the power cable insulation online repair terminal adapter 1 provided in this application to repair the aged power cable 2 has the characteristics of simple operation, convenient installation and disassembly, safety and stability, better repair effect, and low cost.

[0038] See Figure 3 An embodiment of the present application also provides an online repair device for a power cable 2, comprising the above-mentioned power cable insulation online repair terminal adapter 1, a liquid storage tank, an air compressor, a high-voltage power supply, a power cable 2 to be repaired, a rear-end adapter, a rear-end adapter outlet valve and a residual liquid tank.

[0039] The liquid storage tank is connected to the pneumatic valve 104. The air compressor is connected to the liquid storage tank. A high-voltage power supply is connected to the insulated conductor 103. The first end of the power cable 2 to be repaired is connected to the connecting conductor 105 and the insulating sleeve 106, respectively. A rear-end adapter is connected to the second end of the power cable 2 to be repaired. The rear-end adapter outlet valve is connected to the rear-end adapter. The residual liquid tank is connected to the adapter outlet valve.

[0040] In addition, the air compressor, liquid storage tank, power cable insulation online repair terminal adapter 1, rear end adapter, rear end adapter outlet valve, and residual liquid tank are all connected through PU pneumatic hoses, and valves are set on each PU pneumatic hose.

[0041] The embodiment of the present application further provides an application method of the above-mentioned power cable insulation online repair terminal adapter 1, comprising the following steps:

[0042] Step 1: Assess the insulation level of the power cable 2 to be repaired and check the condition of related equipment required for repair.

[0043] The above steps ensure the safety of the entire repair process.

[0044] Step 2: Connect the air compressor, liquid storage tank, and pneumatic valve 104 in sequence, connect the high-voltage power supply to the insulated wire 103, connect the first end of the power cable 2 to be repaired to the connecting conductor 105 and the insulating sleeve 106 respectively, and connect the second end of the power cable 2 to be repaired, the rear-end adapter, the rear-end adapter outlet valve, and the residual liquid tank in sequence.

[0045] After completing the above steps, perform an airtightness check.

[0046] Step 3: Inject the power cable repair liquid in the liquid storage tank into the insulating shell 101 through the injection channel 1012 at a preset pressure. After the power cable repair liquid overflows from the outlet of the rear-end adapter, close the outlet valve of the rear-end adapter and the pneumatic valve 104; at the same time, turn on the high-voltage power supply and apply industrial frequency alternating current to the cable core 201 of the power cable 2 to be repaired in accordance with the regulations; maintain the pressure and voltage for a preset time to allow the power cable repair liquid to fully penetrate into the defective position of the insulation layer 203 of the power cable 2 to be repaired to undergo hydrolysis and condensation reaction, and then turn off the high-voltage power supply.

[0047] In the above steps, to ensure rapid and effective diffusion of the repair fluid within the insulation of power cable 2, an external pressure of 0.2-0.3 MPa is typically applied, with the repair fluid injected and diffused under the pressure of the gas. Optionally, the preset pressure is 0.2 MPa. The power frequency AC voltage is less than 10 kV. The preset time is at least 24 hours.

[0048] Furthermore, during the above steps, the air compressor generates 0.2 MPa of air pressure, driving the power cable repair liquid in the reservoir through injection channel 1012 into the cavity of insulating housing 101, where it comes into contact with cable core 201. Under the action of air pressure, the power cable repair liquid is injected into cable core 201 and discharged through the outlet valve of the rear adapter. Insulating sealant is filled between insulated conductor 103 and energizing channel 1011, ensuring the airtightness of this port. Therefore, the live repair process of power cable 2 is achieved through energizing channel 1011 and injection channel 1012.

[0049] Step 4: Open the pneumatic valve 104 and the adapter outlet valve to discharge the remaining power cable repair liquid and the waste liquid generated by the hydrolysis and condensation reaction from the pneumatic valve 104 and the adapter outlet valve. The repair of the power cable 2 is completed.

[0050] In general, the power cable insulation online repair terminal adapter 1 of the present application is easy to install and disassemble, and ensures airtightness. It solves the problem that the adapter cannot meet the airtightness requirements of the device, and the installation and disassembly process is difficult, which cannot meet the needs of on-site short-term power outage repair. At the same time, it combines pressure injection and voltage application, achieving rapid diffusion of the repair fluid while being able to move in a directional manner to the location of the insulation defect, thereby greatly improving the repair efficiency of the cable 2 insulation. The power cable insulation online repair terminal adapter 1 of the present application and its application are of great significance and economic and social value for the large-scale promotion of the application of cable 2 online repair technology.

[0051] This application conducted an accelerated water tree aging test, a traditional injection repair test, and a live repair test on a power cable 2 sample. Polarization-depolarization current (PDC) tests were performed on the aged power cable 2 samples using different repair methods before and after repair to analyze the dielectric properties of the insulation. The comparative experimental test results show that the power cable insulation online repair terminal adapter 1 provided by this application can achieve live repair of the power cable 2, and the repair rate is higher than that of the traditional injection repair, and the repair effect is better than that of the traditional injection repair. The details are as follows:

[0052] Experimental example

[0053] 1. Acquisition of aged power cable 2 samples:

[0054] Select YJLV22-8.7 / 10 cross-linked polyethylene (XLPE) insulated power cable 2, the cable core 201 is an aluminum conductor with a cross-sectional area of ​​95mm 2Two 40cm long power cable samples were cut. To prevent creeping discharge, 10cm of the outer semiconductive layer 202 was removed from each end toward the center, leaving a 20cm-long area of ​​outer semiconductive layer 202 in the center for subsequent water tree aging testing. Furthermore, 1.5cm of XLPE insulation was removed from each end of the power cable sample, exposing the cable core 201 to serve as the application point for the high-voltage power supply.

[0055] An AC current of 7.5 kV and 400 Hz was applied to two power cable samples for an accelerated water tree aging test. The aging time was 40 days, and two aged power cable samples were obtained, which were designated as group A aged power cable samples and group B aged power cable samples.

[0056] 2. Preparation of power cable repair fluid

[0057] The power cable repair fluid used in the repair experiment is silicone power cable repair fluid (with 7% by mass of isopropyl titanate added). The power cable repair fluid can be obtained by stirring at room temperature for about 20 minutes using a magnetic stirrer.

[0058] 3. Repair experiment of aging power cable 2

[0059] For the aging power cable sample 2 in group A, a live repair experiment was conducted according to the following steps:

[0060] Step 1: Before repair, evaluate the insulation level of the aged power cable 2 sample and check the condition of the related equipment required for repair to ensure the safety of the entire repair process.

[0061] Step 2: Follow Figure 3 , connect the air compressor 3, the liquid storage tank 4, and the pneumatic valve 104 in sequence, connect the high-voltage power supply 5 to the insulated wire 103, connect the first end of the aged power cable 2 sample to the connecting conductor 105 and the insulating sleeve 106 respectively, connect the second end of the aged power cable 2 sample, the rear-end adapter 6, the rear-end adapter outlet valve 7, and the residual liquid tank 8 in sequence, and then perform an air tightness check.

[0062] Step 3: After the air tightness check is completed, the power cable repair liquid in the liquid storage tank 4 is injected into the insulating shell 101 through the injection channel 1012 at a pressure of 0.2 MPa. After the power cable repair liquid overflows from the outlet of the rear-end adapter 6, the rear-end adapter outlet valve 7 and the pneumatic valve 104 are closed. At the same time, the high-voltage power supply 5 is turned on, and industrial frequency alternating current (less than 10 kV) is applied to the cable core 201 of the aged power cable 2 sample in accordance with the regulations; the pressure and voltage are maintained for at least 24 hours to allow the power cable repair liquid to fully penetrate into the defective position of the insulation layer 203 of the aged power cable 2 sample for hydrolysis and condensation reaction, and then the high-voltage power supply 5 is turned off.

[0063] Step 4: After power is turned off, open the pneumatic valve 104 and the adapter outlet valve to discharge the remaining power cable repair liquid and the waste liquid generated by the hydrolysis condensation reaction from the pneumatic valve 104 and the adapter outlet valve. The repair of the power cable 2 is completed.

[0064] A traditional injection repair experiment was conducted on sample 2 of the aged power cable in group B, following the steps below:

[0065] Step 1: Follow Figure 4 , connect the air compressor 3', liquid storage tank 4', residual liquid tank 8', aged power cable 2 sample, front-end adapter 9, rear-end adapter 6', rear-end adapter outlet valve 7', first valve 10, and second valve 11, and perform an air tightness check.

[0066] Step 2: After the air tightness check is completed, the power cable repair liquid is injected into the cable core 201 of the aged power cable 2 sample through the front adapter 9 at a pressure of 0.2 MPa. After the power cable repair liquid flows out from the outlet of the rear adapter 6', the outlet valve 7', the first valve 10, and the second valve 11 of the rear adapter are closed and the pressure is maintained for 24 hours.

[0067] Step 3: After 24 hours, open the first valve 10 and the second valve 11 to drain the remaining power cable repair fluid and waste liquid, and the repair is completed.

[0068] 4. PDC test of power cable 2 before and after repair

[0069] Two samples of aged power cables undergoing conventional injection repair were subjected to continuous PDC testing before and after the repairs, using a polarization voltage of 1 kV and a polarization time of 90 seconds. A series of continuous PDC tests were conducted every four hours after the repairs. The test results showed that the loss factors before and after the repairs, as measured by PDC, were 2.7589%, 1.772%, 1.372%, 0.543%, 0.391%, 0.369%, and 0.376%, respectively.

[0070] Using the same method and conditions as above, continuous PDC tests were performed on two samples of aged power cables undergoing live repair experiments. The test results showed that the loss factor before repair and the loss factor measured by PDC after repair were 2.9936%, 0.599%, 0.305%, 0.223%, 0.227%, 0.182%, and 0.194%, respectively.

[0071] 5. Analysis

[0072] By comparing the PDC test results of the two groups of aged power cable 2 samples through experimental test data, it is proved that both the traditional injection repair and live repair have improved the insulation performance of cable 2 and achieved the repair effect. At the same time, it can be proved that the rate of decrease of the loss factor of the aged power cable 2 sample in the live repair experiment is significantly greater than that in the traditional injection repair experiment, and the final loss factor value of cable 2 is smaller, which proves that live repair can cause the power cable repair liquid to migrate in a directional manner, specifically increase the effective concentration of the power cable repair liquid in the water tree area, promote the forward progress of the hydrolysis condensation reaction, and improve the water tree repair effect. The loss factor test results of cable 2 in the two groups of experiments are as follows: Figure 5 shown.

[0073] The same or similar numbers in the drawings of this embodiment correspond to the same or similar parts; in the description of this application, it should be understood that if the terms "upper", "lower", "left", "right" and so on indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the drawings. This is only for the convenience of describing this application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, the terms describing the position relationship in the drawings are only used for illustrative purposes and cannot be understood as a limitation on this patent. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0074] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present application should be included in the scope of protection of the present application.

Claims

1. A power cable insulation online repair terminal adapter, characterized in that: include: An insulating shell having a cavity, wherein the insulating shell has a power supply channel, a liquid injection channel, and a connection channel respectively connected to the cavity; a power switch conductor mounted in the cavity; an insulated wire passing through the powered channel and being sealed to an inner wall of the powered channel, and the insulated wire is electrically connected to the power switch conductor; A pneumatic valve is installed at the injection channel; a connecting conductor, electrically connected to the cable core of the power cable to be repaired, and the connecting conductor passes through the connecting channel, and the connecting conductor is electrically connected to the power switch conductor; an insulating sleeve, which is sleeved on the outside of the power cable to be repaired and is sealed to the outer wall of the power cable to be repaired, and the insulating sleeve is in communication with the connecting channel and is sealed to the outer peripheral wall of the connecting channel; The power switch conductor has an insertion channel for inserting the insulated wire. The power switch conductor also has two springs. The gap between the two springs is for inserting the connecting conductor. The two springs clamp and fix the connecting conductor.

2. The power cable insulation online repair terminal adapter according to claim 1, characterized in that: Also includes: A power switch conductor insulating base having a mounting channel, wherein a first end of the mounting channel is for inserting the power switch conductor, a second end of the mounting channel is for inserting the insulated wire, and is sealed to an outer wall of the insulated wire; The connecting rods include two connecting rods, which are respectively supported on both sides of the power switch conductor insulation base and fixedly connect the power switch conductor insulation base and the insulation shell.

3. The power cable insulation online repair terminal adapter according to claim 1, characterized in that: A first insulating sealant is filled between the insulated wire and the inner wall of the electrification channel, and a second insulating sealant is filled between the outer wall of the connecting channel and the insulating sleeve.

4. The power cable insulation online repair terminal adapter according to claim 2, characterized in that: A third insulating sealant is filled between the insulated wire and the inner wall of the installation channel.

5. The power cable insulation online repair terminal adapter according to claim 2, characterized in that: An insulating waterproof layer is wrapped around the outer semiconductive layer of the power cable to be repaired. The insulating waterproof layer is sleeved inside the insulating sleeve along with the power cable to be repaired and fits the inner wall of the insulating sleeve.

6. The power cable insulation online repair terminal adapter according to claim 1, characterized in that: Also includes: The throat clamps include two, both of which are clamped on the outside of the insulating sleeve, and one of the throat clamps is clamped at the sealed connection between the insulating sleeve and the connecting channel, and the other throat clamp is clamped at the sealed connection between the insulating sleeve and the power cable to be repaired.

7. A power cable online repair device, characterized in that: include: The power cable insulation online repair terminal adapter according to any one of claims 1 to 6; a liquid storage tank connected to a pneumatic valve; an air compressor connected to the liquid storage tank; A high voltage power supply connected to the insulated wire; The power cable to be repaired has a first end connected to a connecting conductor and an insulating sleeve respectively; a rear end adapter connected to the second end of the power cable to be repaired; a rear end adapter outlet valve connected to the rear end adapter; The residual liquid tank is connected to the adapter outlet valve.

8. An application method of the power cable insulation online repair terminal adapter according to any one of claims 1 to 6, characterized in that: The following steps are involved: Connect the air compressor, the liquid storage tank, and the pneumatic valve in sequence, connect the high-voltage power supply to the insulated wire, connect the first end of the power cable to be repaired to the connecting conductor and the insulating sleeve respectively, and connect the second end of the power cable to be repaired, the rear end adapter, the rear end adapter outlet valve, and the residual liquid tank in sequence; The power cable repair liquid in the liquid storage tank is injected into the insulating housing through the liquid injection channel at a preset pressure. After the power cable repair liquid overflows from the outlet of the rear-end adapter, the outlet valve of the rear-end adapter and the pneumatic valve are closed. At the same time, the high-voltage power supply is turned on to apply industrial frequency alternating current to the cable core of the power cable to be repaired. The pressure and voltage are maintained for a preset time to allow the power cable repair liquid to fully penetrate the defective position of the insulation layer of the power cable to be repaired to undergo a hydrolysis and condensation reaction, and then the high-voltage power supply is turned off. The pneumatic valve and the adapter outlet valve are opened to discharge the remaining power cable repair liquid and the waste liquid generated by the hydrolysis and condensation reaction from the pneumatic valve and the adapter outlet valve, and the power cable repair is completed.

9. The application method according to claim 8, characterized in that: Before connecting the air compressor, the liquid storage tank, and the pneumatic valve in sequence, the insulation level of the power cable to be repaired is evaluated, and the conditions of the related equipment required for the repair are checked.

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