Construction method for live connection and leading of 35kV power line of high-voltage cable

Abstract

The invention discloses a construction method for connecting a high-voltage cable with a 35kV power line in an electrified manner, which is used for solving the problems that the power supply commissioning of a construction site is delayed due to the phenomena that the traditional overhead line T-connection power taking, the overhead line phase spacing safety distance and the high-voltage wire to ground safety distance cannot be ensured, the power failure coordination procedure is complicated, the later operation and maintenance cost is increased, the power utilization risk is increased and the like. The temporary power utilization system belongs to the technical field of temporary power utilization. In temporary electric power engineering construction, the 35kV high-voltage cable is adopted for connection and electricity taking, safety and quality are guaranteed, the temporary electricity connection speed is increased, and the construction cost is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of temporary power supply, and in particular relates to a construction method for live connection of a high-voltage cable to a 35kV power line. Background Art

[0002] At present, temporary power supply projects at construction sites generally use overhead lines to connect high voltage to power-consuming points such as bridges, tunnels, steel bar processing plants, and mixing stations at the construction site. Temporary power supply is quickly connected and put into operation in the early stage, safe and reliable in the mid-term, and convenient in the later stage of operation and maintenance, which is crucial to the normal development of various work at the construction site.

[0003] Existing technology generally uses overhead line T-connections for power supply. The T-connection terminal pole is typically connected to the receiving substation area with a conductor. This results in on-site construction being limited by the deviation of the main line T-connection terminal pole from the power supply direction of the substation area, the inability to ensure safe phase-to-phase distances, and the large height difference between the T-connection terminal pole and the power supply point of the substation area, resulting in insufficient safe distance between the conductor and the ground. This delays power supply commissioning. Furthermore, the use of overhead line T-connections limits the operation of mechanical equipment and facility construction at the subsequent construction site to the minimum safe distance from the overhead high-voltage lines. Vegetation under the overhead lines needs to be regularly cleared during subsequent operation and maintenance, which poses a high risk of short circuit tripping and electric shock caused by vegetation contacting the lines.

[0004] We define the T-contact terminal pole as the incoming power side and the substation area as the receiving power side. Summary of the Invention

[0005] The purpose of the present invention is to provide a construction method for live connection of high-voltage cables to 35kV power lines, which is used to solve the defects of traditional overhead line T-connection power supply, the inability to guarantee the safe distance between the phases of the overhead lines and the safe distance between the high-voltage conductors and the ground, the complicated power outage coordination procedures, the increased subsequent operation and maintenance costs, and the increased risks of electricity use, which lead to delays in power supply and operation at the construction site and increased risks of electricity use.

[0006] The present invention is achieved by adopting the following technical solutions: A construction method for live connection of a high-voltage cable to a 35kV power line comprises the following steps: Step 1: Install the substation area on the receiving side and erect the lines and T-junction terminal poles on the incoming side; The T-contact terminal poles all include a first lightning arrester, a first isolating switch, and a first drop-out fuse; The substation area includes high-voltage metering devices, vacuum load switches, transformers, primary distribution boxes, secondary lightning arresters, secondary isolation switches, and secondary drop-out fuses; Step 2: Laying high voltage cables; Step 3: Production of 35kV cold shrinkable high voltage cable head; Step 4: High voltage cable insulation and withstand voltage test; Step 5: The first isolating switch and the first drop-out fuse on the incoming call side are disconnected; When the power is cut off on the incoming call side, disconnect the first isolating switch and then the first drop-out fuse at the T-contact terminal rod to ensure that the current is completely cut off and the personal safety of the operators is guaranteed; Step 6: Test the electricity; Step 7: The second isolating switch and the second drop-out fuse on the receiving side are disconnected; When the power is cut off on the receiving side, the substation area disconnects the outgoing line switch of the first-level distribution box, the incoming line switch of the first-level distribution box, the vacuum load switch, the second drop-out fuse, and the second isolating knife switch in sequence; Step 8: Connect and fix the high-voltage cable; One end of the high-voltage cable is connected to the high-voltage metering device in the substation area and fixed to ensure that the end of the high-voltage cable is not pulled due to its own weight. The other end is connected to the lower end of the first drop-out fuse on the T-contact terminal pole to draw power; Step 9: Close the isolating switch and drop-out fuse on the incoming and receiving sides in sequence; When power is transmitted, the high-voltage metering device, second isolating switch, second drop-out fuse, vacuum load switch, transformer, and primary distribution box on the incoming power side are connected to the receiving power side in sequence. This ensures that the current can be smoothly connected to the system during the power transmission process, avoiding any impact on the equipment on the receiving side. Step 10: Check the operating status of the transformer; When supplying power to a transformer, the operating status of the transformer should be closely monitored, including sound, temperature, and electrical parameters. If any abnormality is found, timely measures should be taken to ensure the normal operation of the transformer. Step 11: Run at no load for 24 hours; Run the transformer at no load for 24 hours to check the performance of the transformer and detect whether there is any abnormal sound or heating; Step 12: Acceptance; Organize safety and technical briefings, handle the power transfer procedures for the substation, and hand it over to the power-consuming unit's full-time electrician for management.

[0007] Further preferably, in step 2, the high-voltage cable model is checked for accuracy, the high-voltage cable length is checked, and the high-voltage cable laying margin is considered; the high-voltage cable is prevented from being damaged by external forces during the laying process: when laying the high-voltage cable, the high-voltage cable is prevented from being damaged by external forces such as impact and pulling to ensure the integrity and safety of the high-voltage cable.

[0008] Further preferably, step three includes the following steps: S31: Strip the insulation layer. Use wire strippers to strip the insulation layer near both ends of the high-voltage cable. Do not damage the conductor when stripping. S32: Wrap a 1-2mm thick semi-conductive tape on the step between the copper shielding tape and the outer semi-conductive layer; S33 test high voltage cable. After completing the high voltage cable connection, the electrical performance test of the entire high voltage cable should be carried out; S34 Recording and Acceptance: When connecting high-voltage cables, the construction process and test results must be recorded in detail; During S35 acceptance, check whether the record content is consistent with the actual construction situation to ensure construction quality and traceability.

[0009] Further preferably, the recorded content in S34 includes: the tools and materials used, the stripping length, the crimping tube specifications, and the test data.

[0010] Further preferably, in step 4, the withstand voltage and insulation tests are qualified and the discharge treatment is performed, the phase is checked, the phase sequence is clear, and the installation is correct.

[0011] Further preferably, step six includes the following steps: When using an electroscope, it is important to ensure that its rated voltage is compatible with the voltage level of the electrical equipment being tested. When testing the S62 for electricity, the operator must wear insulating gloves and insulating boots.

[0012] Further preferably, the power-off operation sequence of the drop-out fuse in steps five and seven is to pull the middle phase first and then the two side phases, the power-off operation sequence of the first drop-out fuse in step five is to pull the middle phase first and then the two side phases, and the power-on operation sequence of the first drop-out fuse in step five is to close the two side phases first and then the middle phase.

[0013] Further preferably, in step eight, the high-voltage cables on both sides of the incoming and receiving power lines are fixed with clamps, and the clamps have measures to prevent the high-voltage cables from being damaged in insulation. The high-voltage cables should be fixed intact and the high-voltage cable heads should not be pulled by external forces.

[0014] Further preferably, the T-contact terminal rod assembly in step 1 is specifically as follows: a. Assemble seven crossarms on the T-junction terminal pole. Begin installing from the top of the pole at intervals of 2m, 0.8m, 1.5m, 1.5m, 0.8m, and 1m, respectively. The lowest crossarm is 2.4m from the ground. The crossarms on the T-junction terminal pole, from top to bottom, are defined as the first, second, third, fourth, fifth, sixth, and seventh crossarms. b. The top of the first cross arm is connected to the first insulating magnetic column, which is used to install the hanging wire. There are three sets of them; c. A first isolation switch is connected between the second crossarm and the third crossarm, the first isolation switch is connected to an operating connecting rod, the operating connecting rod is connected to the isolation switch operating handle; d. The fourth cross arm is connected to a second insulating magnetic column, which is used to install the lead wire. There are three sets of second insulating magnetic columns; e. A first drop-out fuse is connected between the fifth crossarm and the sixth crossarm; f. The seventh cross arm is connected to a high-voltage cable. Specifically, a clamp is fixed to the high-voltage cable in the middle of the seventh cross arm and measures are taken to prevent insulation damage. The high-voltage cable passes through a high-voltage cable protection pipe and extends underground.

[0015] The present invention has the following beneficial effects: 1. The present invention eliminates the power outage procedures required for the installation of the terminal pole connection. It only requires disconnecting the isolation switch and the drop-out fuse. After the electrical safety test, live operation can be carried out, which significantly shortens the construction period, enables the substation to quickly prepare for power supply conditions, and shortens the connection work with the main line to 1 hour, realizing early and safe power supply to multiple work points within the section. 2. The present invention solves the problem of the 35kV trunk line T-junction terminal pole deviating from the power supply direction of the transformer station area, ensuring a safe distance between phases and eliminating potential safety hazards; 3. This invention proposes an effective solution to the problem of insufficient safe distance between the conductor and the ground caused by the large height difference between the T-junction terminal pole and the power supply point in the transformer station area, thus ensuring construction and operation safety; 4. This invention overcomes the challenge of construction site machinery and equipment operation and facility construction being restricted by the minimum safe distance of overhead high-voltage lines. While ensuring reliable power supply, it maximizes the clearance of the construction area and protects the safety of personnel and property. 5. This invention breaks through the limitations of mountainous terrain, reduces land acquisition and coordination difficulties, reduces costs through optimized line design, and accelerates construction progress; 6. This invention abandons the traditional overhead wire installation and hardware installation, reduces the time of high-altitude operation, saves labor costs, and reduces the risk of high-altitude operation; 7. The present invention eliminates the need for regular cleaning of vegetation under overhead wires, thus protecting the ecological environment to the greatest extent possible and preventing the risk of short circuit tripping and electric shock caused by vegetation contacting the wires. 8. The present invention has advanced technology, controllable quality, convenient troubleshooting, and greatly reduces subsequent maintenance costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0017] In order to more clearly illustrate the embodiments of the present invention 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, for ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 It is a schematic diagram showing the structure of the T-contact terminal rod.

[0019] In the figure: Ⅰ-incoming side, 1-first insulating magnetic column, 2-first isolating knife switch, 3-operating connecting rod, 4-second insulating magnetic column, 5-first drop-out fuse, 6-high-voltage cable, 7-operating handle, 8-high-voltage cable protection tube. DETAILED DESCRIPTION

[0020] In order to more clearly understand the above-mentioned objects, features and advantages of the present invention, the solutions of the present invention will be further described below. It should be noted that, in the absence of conflict, the embodiments of the present invention and the features therein can be combined with each other.

[0021] In the description, it should be noted that the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance.

[0022] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein; it is obvious that the embodiments in the specification are only part of the embodiments of the present invention, rather than all the embodiments.

[0023] The specific embodiments of the present invention are described in detail below with reference to the accompanying drawings.

[0024] A construction method for live connection of a high-voltage cable to a 35kV power line comprises the following steps: Step 1: Install the substation area on the receiving side and erect the lines and T-junction terminal poles on the incoming side; The T-contact terminal poles each include a first lightning arrester, a first isolating switch 2, and a first drop-out fuse 5; The substation area includes high-voltage metering devices, vacuum load switches, transformers, primary distribution boxes, second lightning arresters, second isolation switches and second drop-out fuses.

[0025] The T-contact terminal rod assembly is as follows: a. Assemble seven crossarms on the T-junction terminal pole. Begin installing from the top of the pole at intervals of 2m, 0.8m, 1.5m, 1.5m, 0.8m, and 1m, respectively. The lowest crossarm is 2.4m from the ground. The crossarms on the T-junction terminal pole, from top to bottom, are defined as the first, second, third, fourth, fifth, sixth, and seventh crossarms. b. The top of the first crossarm is connected to the first insulating magnetic column 1; c. A first isolation switch 2 is connected between the second crossarm and the third crossarm. The first isolation switch 2 is connected to an operating connecting rod 3, and the operating connecting rod 3 is connected to the isolation switch operating handle 7; d. The fourth cross arm is connected to a second insulating magnetic column 4; e. A first drop-out fuse 5 is connected between the fifth crossarm and the sixth crossarm; The seventh cross arm is connected to a high-voltage cable 6 , which passes through a high-voltage cable protection tube 8 and extends underground.

[0026] Step 2: Laying of high voltage cable 6; Check the model of the high-voltage cable 6 and the length of the high-voltage cable 6 and consider the laying margin of the high-voltage cable 6; avoid the high-voltage cable 6 from being damaged by external forces during the laying process: When laying the high-voltage cable 6, avoid the high-voltage cable 6 from being damaged by external forces such as impact and pulling to ensure the integrity and safety of the high-voltage cable 6.

[0027] Step 3: Production of 35kV cold shrinkable high voltage cable head; S31: Strip the insulation layer. Use wire strippers to strip the insulation layer from both ends of the high-voltage cable 6. Do not damage the conductor when stripping. S32: Wrap a 1-2mm thick semi-conductive tape on the step between the copper shielding tape and the outer semi-conductive layer; S33 tests the high-voltage cable 6. After the high-voltage cable 6 is connected, the electrical performance test of the entire high-voltage cable 6 should be performed. The test results should meet the requirements of relevant standards to ensure the reliability of the high-voltage cable 6. S34 Recording and Acceptance: When connecting the high-voltage cable 6, the construction process and test results shall be recorded in detail; the record content shall include but not be limited to: the tools and materials used, stripping length, crimping tube specifications, and test data.

[0028] During S35 acceptance, check whether the record content is consistent with the actual construction situation to ensure construction quality and traceability.

[0029] Important considerations during implementation: The production of cold-shrink high-voltage cable connectors must be carried out in clear, dry weather. The construction site should be clean, free of flying dust and paper scraps. Failure to address environmental factors during production can lead to the formation of air gaps in the insulation of the high-voltage cable connector due to the ingress of dust and impurities. This can cause partial discharge under strong electric fields, leading to insulation breakdown and resulting in failure of the high-voltage cable connector.

[0030] If manufactured in a humid environment, the high-voltage cable 6 is easily affected by moisture, which may reduce the overall insulation level. In addition, moisture may easily enter the cable to form air gaps, which may cause partial discharge.

[0031] Strip and clean the semi-conductive shielding layer. The semi-conductive shielding layer in the high-voltage cable 6 mainly plays the role of uniforming the electric field and eliminating air gaps, reducing or eliminating the amount of partial discharge. However, it must be stripped and cleaned when making the high-voltage cable head. Its main purpose is to ensure the creepage distance of the high voltage to the ground.

[0032] When manufacturing cold-shrink high-voltage cable heads, ensure that the outer semi-conductive layer breaks neatly and smoothly transitions to the insulation layer. The insulation layer must be free of scratches, knife marks, and conductive particles. Measures such as wrapping semi-conductive tape should be taken to improve the electric field concentration at the shield end of the high-voltage cable 6. If these measures are not taken, the electric field will concentrate at the shield break of the operating high-voltage cable 6, becoming a weak link and easily causing insulation breakdown failure of the high-voltage cable 6.

[0033] After the production is completed, leak-proofing, moisture-proofing and sealing measures should be taken. After the cold-shrink high-voltage cable head is completed, the semiconductor self-adhesive tape should be wrapped around the ends of the cold-shrink tubes and cold-shrink finger sleeves of each phase after shrinkage. Wrapping the self-adhesive tape is a key link in the moisture-proof sealing of the cold-shrink joint. It should be wrapped from one end of the joint to the other end using the semi-overlap method, and then wrapped in the opposite direction to the starting end. After each layer is wrapped, both hands should be used to hold it tightly in turn to make it adhere better. The tension should be appropriate when wrapping to ensure that the wrapping is tight and without gaps. If these leak-proofing, moisture-proofing and sealing measures are not taken, the high-voltage cable head will easily be infiltrated with moisture, impurities, etc. during operation, causing insulation breakdown failure of the high-voltage cable head.

[0034] Step 4: Insulation and withstand voltage test of high voltage cable 6; In step 4, the withstand voltage and insulation tests are qualified and the discharge treatment is carried out. The phase is checked and the phase sequence is clear and the installation is correct.

[0035] It should be noted that after the on-site 35kV high-voltage cable 6 is laid, the withstand voltage test and insulation resistance test must meet the standards before proceeding to the next step.

[0036] Step 5: On the incoming call side, the first isolating switch 2 and the first drop-out fuse 5 are disconnected. Power outage and power supply must be performed by professionals with high-voltage electrician qualification certificates. The work area must be demarcated and unauthorized personnel are not allowed to approach. The operation supervision system must be strictly implemented, with one person operating and one person supervising. The operator is in front and the supervisor is behind. They must wear insulating boots and insulating gloves with a 35kV insulation grade and use 35kV insulating rods to perform power outage and power supply operations.

[0037] When the power is cut off on the incoming call side, disconnect the first isolating switch 2 and then the first drop-out fuse 5 at the terminal rod at the T-contact to ensure that the current is completely cut off and the personal safety of the operators is guaranteed; Step 6: Test the electricity; The operation supervision system must also be implemented conscientiously.

[0038] When using an electroscope, it is important to ensure that its rated voltage is compatible with the voltage level of the electrical equipment being tested. When testing the S62 for electricity, the operator must wear insulating gloves and insulating boots.

[0039] Step 7: The second isolating switch and the second drop-out fuse on the receiving side are disconnected; When the power is cut off on the receiving side, the substation area will disconnect the outgoing line switch of the first-level distribution box, the incoming line switch of the first-level distribution box, the vacuum load switch, the second drop-out fuse, the second isolation switch and other equipment in sequence; Step 8: Connect and fix the high-voltage cable 6; The high-voltage cables 6 on both sides of the incoming and receiving power should be fixed with clamps. The clamps should have measures to prevent the high-voltage cables 6 from being damaged in insulation. The high-voltage cables 6 should be fixed intact and the high-voltage cable heads should not be pulled by external forces.

[0040] In this embodiment, the high-voltage cable is connected to the high-voltage metering device at the substation area (the receiving side) and the terminal pole (the incoming side). Phases A, B, and C of the high-voltage cable are connected to the lower ends of the first drop-out fuses at the T-junction terminal pole, respectively, to ensure the main line connection remains uninterrupted.

[0041] During implementation, the high-voltage cable is first connected to the substation area on the receiving side and then the power is drawn from the T-contact terminal pole.

[0042] One end of the high-voltage cable is connected to the high-voltage metering device in the substation area and fixed, and it is ensured that the head end of the high-voltage cable is not pulled due to its own weight; the other end is connected to the T-contact terminal pole, which is the incoming power side, and the ABC phases of the high-voltage cable are respectively powered by the lower ends of the ABC phases of the first drop-out fuse at the T-contact terminal pole. At this time, the first isolating knife switch and the first drop-out fuse at the T-contact terminal pole are in the disconnected state. The minimum safe distance between the human body and the 35kV live body is required to be greater than 0.6 meters, and the upper end of the live part is 3.8 meters away from the high-voltage operator (taking into account the 0.8-meter operating margin for the operator's high-voltage cable head connection work), so that the connection can be achieved while ensuring safety and without interrupting the power supply to the main line.

[0043] Step 9: On the incoming power side I and the receiving power side, close the second isolating switch and the second drop-out fuse in sequence; When power is supplied, the high-voltage metering device, second isolating switch, second drop-out fuse, vacuum load switch, transformer, and primary distribution box on the incoming power side I to the receiving power side are supplied with power in sequence. This ensures that the current can be smoothly connected to the system during the power supply process, avoiding any impact on the equipment on the receiving side. Step 10: Check the operating status of the transformer; When supplying power to a transformer, the operating status of the transformer should be closely monitored, including sound, temperature, electrical parameters, etc. If any abnormality is found, timely measures should be taken to ensure the normal operation of the transformer; Step 11: Run at no load for 24 hours; Run the transformer at no load for 24 hours to check the performance of the transformer and detect any abnormalities such as abnormal sounds or heat generation; Step 12: Acceptance; Organize safety and technical briefings, handle the power transfer procedures for the substation, and hand it over to the power-consuming unit's full-time electrician for management.

[0044] It should be noted that operators must not use any impact when opening or closing a dropout fuse. Impact can damage the dropout fuse, such as breaking or cracking the insulator, deflecting the duckbill, or pulling or breaking the operating ring. When opening or closing a dropout fuse, operators must avoid excessive force or impact to avoid damage, and must ensure that the opening and closing operations are in place.

[0045] It should be noted that the power-off operation sequence of the drop-out fuse is to pull the middle phase first and then the two side phases, and the power-on operation sequence of the drop-out fuse is to close the two side phases first and then the middle phase.

[0046] The reason for tripping the center phase first during a power outage is that the combined current when the center phase is disconnected is less than that of the side phases (part of the circuit load is transferred to two phases), resulting in a smaller arc and no risk to the side phases. When the second phase (side phase) dropout fuse is operated, the current is higher, and the center phase has already opened. The two other dropout fuses are farther apart, preventing arc extension and a short circuit between phases. During strong winds, power outages should be performed in the following order: center phase first, leeward phase second, and windward phase last. When power is restored, the windward phase first, then the leeward phase, and finally the center phase to prevent wind-induced arcing and short circuits.

[0047] When this embodiment is applied, a 6-35kV-YJLV22-3*70mm2 high-voltage cable 6 is used to connect and draw power. The safe working distance on the substation area is 2.5m. The second isolating knife switch and the second drop-out fuse are disconnected, and live work can be carried out, eliminating the power outage procedure and shortening the construction period. The substation area is ready for power supply, and the connection work with the main line is shortened to 1 hour.

[0048] The material list is as follows:

[0049] The construction machinery and tools mainly include: hydraulic crimping pliers, insulation stripping tools, hacksaw, 35kV insulating boots, 35kV insulating gloves, 35kV electroscope, 35kV high-voltage pull rod, ground resistance tester, megohmmeter, and vernier caliper.

[0050] The adoption of the present invention facilitates construction, improves labor productivity, ensures the efficiency, safety, reliability and economy of power supply at the construction site, provides power to multiple work points in the section in advance, enables the main project construction to proceed smoothly, and improves the company's social reputation.

[0051] The present invention is applicable to construction sites of 10kV and 35kV voltage-level buildings, roads, railways, etc., and early temporary power engineering construction, and serves as a reference for other formal power engineering projects.

[0052] The present invention has the following advantages: the direction of the 35kV trunk line T-contact terminal pole deviates from the power supply direction of the substation area, and the phase-to-phase safety distance cannot be guaranteed; the high-voltage cable 6 is laid for power supply, avoiding the problem of straightening the trunk line and being affected by the terrain, landform, and installation specifications of the mountainous area. There is a significant height difference between the 35kV trunk line T-contact terminal pole and the power supply point of the substation area, which makes it difficult to ensure the safe distance between the conductor and the ground. For this reason, we adopt the high-voltage cable 6 power supply method, which not only eliminates the tedious work of regularly cleaning the vegetation under the overhead wires, and protects the local ecological environment to the greatest extent, but also effectively avoids the short-circuit tripping faults and the risk of electric shock to personnel that may be caused by vegetation touching the lines in the later stage.

[0053] The above description is merely a specific embodiment of the present invention, which enables those skilled in the art to understand or implement the present invention. Although detailed descriptions have been made with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents; and such modifications or replacements do not deviate from the essence of the corresponding technical solutions within the scope of the technical solutions of the embodiments, and they should all be included in the scope of protection of the claims.

Claims

1. A construction method for connecting a high-voltage cable to a 35kV power line, characterized by: The following steps are involved: Step 1: Install the substation area on the receiving side and erect the lines and T-junction terminal poles on the incoming side; The T-contact terminal poles each include a first lightning arrester, a first isolating switch (2), and a first drop-out fuse (5); The substation area includes high-voltage metering devices, vacuum load switches, transformers, primary distribution boxes, secondary lightning arresters, secondary isolation switches, and secondary drop-out fuses; Step 2: Laying high voltage cables; Step 3: Production of 35kV cold shrinkable high voltage cable head; Step 4: High voltage cable insulation and withstand voltage test; Step 5: On the incoming call side (I), the first isolating switch (2) and the first drop-out fuse (5) are disconnected; When the incoming power side (I) is powered off, the first isolating switch (2) is disconnected at the T-contact terminal rod first, followed by the first drop-out fuse (5), to ensure that the current is completely cut off and the personal safety of the operator is guaranteed; Step 6: Test the electricity; Step 7: The second isolating switch and the second drop-out fuse on the receiving side are disconnected; When the power is cut off on the receiving side, the substation area disconnects the outgoing line switch of the first-level distribution box, the incoming line switch of the first-level distribution box, the vacuum load switch, the second drop-out fuse, and the second isolating knife switch in sequence; Step 8: Connect and fix the high voltage cable (6); One end of the high-voltage cable (6) is connected to the high-voltage metering device in the transformer substation area and fixed to ensure that the end of the high-voltage cable is not pulled due to its own weight, and the other end is connected to the lower end of the first drop-out fuse (5) on the T-contact terminal pole to obtain power; Step 9: Close the isolating switch (2) and the drop-out fuse (5) on the incoming power side (I) and the receiving power side in sequence; When power is transmitted, the high-voltage metering device, second isolating switch, second drop-out fuse, vacuum load switch, transformer, and primary distribution box on the incoming power side (Ⅰ) are connected to the receiving power side in sequence. This ensures that the current can be smoothly connected to the system during the power transmission process, avoiding any impact on the equipment on the receiving side. Step 10: Check the operating status of the transformer; When supplying power to a transformer, the operating status of the transformer should be closely monitored, including sound, temperature, and electrical parameters. If any abnormality is found, timely measures should be taken to ensure the normal operation of the transformer. Step 11: Run at no load for 24 hours; Run the transformer at no load for 24 hours to check the performance of the transformer and detect whether there is any abnormal sound or heating; Step 12: Acceptance; Organize safety and technical briefings, handle the power transfer procedures for the substation, and hand it over to the power-consuming unit's full-time electrician for management.

2. A construction method for live connection of a high-voltage cable to a 35kV power line according to claim 1, characterized in that: In step 2, the model of the high-voltage cable (6) is checked to be correct, the length of the high-voltage cable (6) is checked, and the laying margin of the high-voltage cable (6) is considered; during the laying process, the high-voltage cable (6) is prevented from being damaged by external forces: when laying the high-voltage cable (6), the high-voltage cable (6) is prevented from being damaged by external impact or pulling, so as to ensure the integrity and safety of the high-voltage cable (6).

3. A construction method for live connection of a high-voltage cable to a 35kV power line according to claim 1, characterized in that: Step 3 includes the following steps: S31 Strip the insulation layer. Use wire strippers to strip the insulation layer near both ends of the high-voltage cable (6). Do not damage the conductor when stripping. S32: Wrap a 1-2mm thick semi-conductive tape on the step between the copper shielding tape and the outer semi-conductive layer; S33 tests the high-voltage cable (6). After the high-voltage cable (6) is connected, the electrical performance test of the entire high-voltage cable (6) shall be performed; S34 Recording and acceptance: When connecting the high voltage cable (6), record the construction process and test results in detail; During S35 acceptance, check whether the record content is consistent with the actual construction situation to ensure construction quality and traceability.

4. A construction method for live connection of a high-voltage cable to a 35kV power line according to claim 3, characterized in that: The contents recorded in S34 include: tools and materials used, stripping length, crimping tube specifications, and test data.

5. The method for connecting a high-voltage cable to a 35kV power line according to claim 1, characterized in that: In step 4, the withstand voltage and insulation tests are qualified and the discharge treatment is carried out. The phase is checked and the phase sequence is clear and the installation is correct.

6. A construction method for live connection of a high-voltage cable to a 35kV power line according to claim 1, characterized in that: Step six includes the following steps: When using an electroscope, its rated voltage must be compatible with the voltage level of the electrical equipment being tested. When testing the S62 for electricity, the operator must wear insulating gloves and insulating boots.

7. A construction method for live connection of a high-voltage cable to a 35kV power line according to claim 1, characterized in that: In step 5, the power-off operation sequence of the first drop-out fuse (5) is to pull the middle phase first and then pull the two side phases. In step 5, the power-on operation sequence of the first drop-out fuse (5) is to close the two side phases first and then close the middle phase.

8. The method for live connection of a high-voltage cable to a 35kV power line according to claim 1, characterized in that: In step eight, the high-voltage cables (6) on both sides of the incoming and receiving power should be fixed with clamps. The clamps should have measures to prevent the high-voltage cables (6) from being damaged in insulation. The high-voltage cables (6) should be fixed well and the heads of the high-voltage cables (6) should not be pulled by external forces.

9. A construction method for live connection of a high-voltage cable to a 35kV power line according to any one of claims 1 to 8, characterized in that: The assembly of the T-contact terminal rod in step 1 is as follows: a. Assemble seven crossarms on the T-junction terminal pole. Begin installing from the top of the pole at intervals of 2m, 0.8m, 1.5m, 1.5m, 0.8m, and 1m, respectively. The lowest crossarm is 2.4m from the ground. The crossarms on the T-junction terminal pole, from top to bottom, are defined as the first, second, third, fourth, fifth, sixth, and seventh crossarms. b. The top of the first cross arm is connected to a first insulating magnetic column (1); c. A first isolating knife switch (2) is connected between the second cross arm and the third cross arm, the first isolating knife switch (2) is connected to an operating connecting rod (3), and the operating connecting rod (3) is connected to an isolating knife switch operating handle (7); d. A second insulating magnetic column (4) is connected to the fourth cross arm; e. A first drop-out fuse (5) is connected between the fifth crossarm and the sixth crossarm; f. The seventh cross arm is connected to a high-voltage cable (6), which passes through a high-voltage cable protection tube (8) and extends underground.

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