XLPE Insulated 4× 70mm² 4× 95mm² 4× 185mm² Aluminium Multicore Underground Power Cable

All three types of cables adopt 4-core high-purity Aluminium Conductors with a purity of ≥99.7%. The 4×70mm² Cable has a single-core conductor cross-sectional area of 70mm², formed by compact stranding of multiple Aluminium Wires with a diameter of 0.25mm-0.3mm. The stranding pitch is 25mm-30mm, the conductor diameter is approximately 8.5mm, the DC resistance of a Single Core at 20℃ is ≤0.512Ω/km, and the total weight of the 4-core conductor is about 220kg per kilometer. The 4×95mm² cable has a single-core cross-sectional area of 95mm², with aluminium wires of the same diameter as the 70mm² specification. The stranding pitch is 30mm-35mm, the conductor diameter is approximately 10mm, the single-core DC resistance is ≤0.387Ω/km, and the total weight of the 4-core conductor is about 300kg per kilometer. The 4×185mm² cable has a single-core cross-sectional area of 185mm², with aluminium wires of 0.3mm-0.35mm in diameter. The stranding pitch is 35mm-40mm, the conductor diameter is approximately 14mm, the single-core DC resistance is ≤0.199Ω/km, and the total weight of the 4-core conductor is about 580kg per kilometer. All three types of conductors can withstand a tensile force of ≥6kN, meeting the mechanical strength requirements for underground laying.

The insulation layer is made of XLPE material, and its thickness increases with the increase of the cross-sectional area. The insulation layer thickness of the 4×70mm² cable is 1.2mm-1.4mm, with the thinnest part not less than 1.0mm; that of the 4×95mm² is 1.4mm-1.6mm, with the thinnest part ≥1.2mm; and that of the 4×185mm² is 1.6mm-1.8mm, with the thinnest part ≥1.4mm. The insulation resistance of all three cables is ≥1000MΩ·km, the dielectric loss tangent at 50Hz is ≤0.003, and the breakdown strength is ≥20kV/mm. The XLPE insulation layer has a long-term operating temperature of 90℃, can withstand a temperature of 250℃ during short circuits (within 5 seconds), and remains flexible without cracking in a low-temperature environment of -40℃.

The sheath is made of HDPE or PVC material. The sheath thickness of the 4×70mm² cable is 1.6mm-1.8mm, with an average thickness of ≥1.7mm and the thinnest part ≥1.4mm; that of the 4×95mm² is 1.8mm-2.0mm, with an average thickness of ≥1.9mm and the thinnest part ≥1.6mm; and that of the 4×185mm² is 2.0mm-2.2mm, with an average thickness of ≥2.1mm and the thinnest part ≥1.8mm. The HDPE sheath has a tensile strength of ≥20MPa and an elongation at break of ≥300%; the PVC Sheath has a tensile strength of ≥12MPa and an elongation at break of ≥150%. Both sheaths have an oxygen index of ≥30, providing good flame retardancy, and excellent acid and alkali resistance. After being immersed in 10% concentration hydrochloric acid and sodium hydroxide solutions for 72 hours, the performance change rate is ≤20%.

All three cables have a rated voltage of 0.6/1kV, with a phase voltage of 0.6kV and a line voltage of 1kV. The overall outer diameter of the 4×70mm² cable is approximately 18mm, the bending radius is ≥8 times the outer diameter (about 144mm), and the weight per kilometer is about 380kg; the outer diameter of the 4×95mm² is approximately 22mm, the bending radius is ≥10 times the outer diameter (about 220mm), and the weight per kilometer is about 500kg; the outer diameter of the 4×185mm² is approximately 28mm, the bending radius is ≥12 times the outer diameter (about 336mm), and the weight per kilometer is about 650kg. At an ambient temperature of 30℃, the current-carrying capacity when directly buried is: 4×70mm² is about 150A-170A, 4×95mm² is about 190A-210A, and 4×185mm² is about 250A-270A. All three cables comply with the requirements of GB/T 12706.1-2020.

In urban power grid transformation, the 4×185mm² cable is used as an underground trunk line to connect urban substations with various distribution areas, undertaking the task of large-capacity power transmission. The urban underground space is complex, and the strong protective sheath of this cable can resist soil pressure and interference from underground pipelines, and its large current-carrying capacity meets the high-load power demand in urban core areas. The 4×95mm² cable is used as a secondary trunk line to connect distribution areas with large communities and commercial centers, balancing transmission capacity and cost. The 4×70mm² cable is suitable for the transformation of distribution branch lines in old communities, and can be flexibly laid in narrow underground pipe corridors to solve the problem of insufficient capacity of the original lines.

In large industrial parks, the 4×185mm² cable is used as an incoming cable to supply power from the park substation to various production plants, meeting the concentrated power demand of large equipment in the factories. Its temperature resistance can adapt to short-term overload during equipment startup, and its corrosion-resistant sheath can resist the erosion of chemical substances that may exist in industrial areas. In medium-sized factory workshops, the 4×95mm² cable is used as a power trunk line to supply power to production line equipment, and its bending performance is convenient for arrangement in the underground pipe network of the workshop. Small processing plants mostly choose the 4×70mm² cable, which has a lower cost and can meet the power demand of medium-power equipment.

In rural power grid upgrading, the 4×70mm² cable is widely used for underground wiring along main roads in villages, connecting township substations with village distribution points. Its lightweight characteristic reduces the difficulty of field construction. In farmland irrigation areas, this cable is directly buried, and its moisture-resistant sheath can adapt to the humid environment in the fields, ensuring stable power supply for irrigation equipment. The 4×95mm² cable is used in township central areas to supply power to concentrated load areas such as small supermarkets and processing plants, with moderate current-carrying capacity and reasonable price.

In municipal engineering, the 4×70mm² cable is used for underground wiring of street lamp systems, directly buried along both sides of the road, and its impact-resistant sheath can withstand external pressures such as vehicle rolling. In the underground power distribution systems of large stadiums and convention centers, the 4×185mm² and 4×95mm² cables are used together, undertaking the main power supply and branch power supply tasks respectively, to meet the power demand of a large number of lighting, air conditioning and other equipment in the venues.

The conductor is made of high-purity aluminium with a purity of ≥99.7%, and its conductivity is improved by removing impurities such as iron and silicon. The density of aluminium is only 2.7g/cm³, and its weight is about 1/3 of that of copper under the same cross-section, which greatly reduces the transportation and laying costs of the cable. To make up for the low mechanical strength of aluminium, a multi-strand compact stranding process is adopted to make the conductor structure compact and improve tensile and bending resistance. At the same time, the oxide film formed on the surface of aluminium has good corrosion resistance, making it suitable for underground humid environments.

The insulation layer is made of XLPE material, which forms a three-dimensional network structure after chemical cross-linking. Compared with ordinary polyethylene, its heat resistance and mechanical strength are significantly improved. XLPE has excellent electrical insulation performance, which can effectively isolate current leakage between conductors, with high insulation resistance and low dielectric loss, ensuring the safety of the cable during long-term operation. In addition, XLPE has strong aging resistance, and its service life in underground environments can reach more than 30 years.

There are two choices for the sheath: HDPE and PVC. The HDPE sheath has higher impact resistance and chemical corrosion resistance, and excellent low-temperature performance, making it suitable for areas with high groundwater levels and strong soil corrosion; the PVC sheath has better flame retardancy and a relatively lower price, suitable for ordinary soil environments. Both sheaths are added with ultraviolet absorbers and antioxidants to improve weather resistance, and can resist the influence of a small amount of light and temperature changes even in shallow underground.

All three cables have a circular structure, with 4 Cores symmetrically arranged around the center. After compact stranding, a Compact Cable core is formed, and the outer layer is wrapped with an XLPE insulation layer and a sheath in sequence, with an overall smooth and round structure. The surface of the cable is printed with clear marks, including model specifications (such as XLPE insulated 4×70mm² aluminium Core Cable), rated voltage, manufacturer, meter marks, etc., which is convenient for identification and cutting during construction. In terms of color, the HDPE sheath is mostly black, and the PVC sheath is available in black and gray, both of which can blend with the underground environment.

First, aluminium ingots are smelted into aluminium liquid, and aluminium rods with a diameter of 9mm-12mm are made through continuous casting. The aluminium rods are drawn through a wire drawing machine in multiple passes to make aluminium wires of the required diameter. A special lubricant is used during the wire drawing process to avoid scratches on the surface of the aluminium wires. Then, according to the cross-sectional specifications, a certain number of aluminium wires are stranded on a compact stranding machine. Each core of 4×70mm² has about 120 aluminium wires, 4×95mm² has about 160, and 4×185mm² has about 280. During stranding, the conductor is compacted through a mold to make the conductor filling factor reach more than 90%, reducing gaps and improving conductivity. After stranding, annealing treatment is carried out to eliminate internal stress and enhance the Flexibility of the conductor.

The Stranded Conductor enters the insulation extrusion process. XLPE particles are added to the extruder hopper after drying treatment (moisture content ≤50ppm). The extruder barrel is heated in three sections, with temperatures of 120℃-140℃, 160℃-180℃, and 180℃-200℃ respectively, to melt and plasticize the XLPE. The molten XLPE is uniformly extruded onto the surface of the conductor through a cross-head mold to form an insulation layer, and the mold size is precisely designed according to the insulation thickness. The extruded Insulated Wire core immediately enters a cooling water tank, and the water temperature is controlled at 20℃-30℃ for rapid cooling and shaping. After that, the insulated wire core enters the cross-linking tube, and the cross-linking reaction is completed in a high-pressure steam environment of 180℃-200℃ and 1.5MPa-2.0MPa to form a stable three-dimensional structure.

After passing the inspection, the insulated wire cores enter the cabling machine. The 4 insulated wire cores are stranded into a cable in an S-shaped direction. The cabling pitch of 4×70mm² is 160mm-200mm, 4×95mm² is 200mm-250mm, and 4×185mm² is 250mm-300mm. During the cabling process, polypropylene rope is filled in the center of the cable core, and asbestos rope (to enhance flame retardancy) is filled in the gaps to make the cable core round and stable. After cabling, a layer of semi-conductive water-blocking tape is wrapped around the outer layer of the cable core to prevent moisture infiltration, and then a layer of non-woven tape is wrapped as an isolation layer.

The cabled core enters the sheath extruder. HDPE or PVC sheath materials are added to the extruder after mixing and plasticizing, and the barrel temperature is controlled at 160℃-190℃ (for HDPE) or 150℃-180℃ (for PVC). The molten sheath material is extruded onto the surface of the cable core through a mold to form a uniform sheath layer, and the mold is precisely processed according to the cable outer diameter. The extruded cable is cooled in sections in a cooling water tank, and the water temperature is gradually reduced from 60℃ to 20℃ to avoid internal stress in the sheath due to sudden cooling. After cooling, the cable is pulled to the take-up machine by a tractor and neatly coiled on the cable reel, with the take-up tension controlled at 5kN-8kN to prevent the cable from stretching and deforming.

The finished cable needs to undergo strict inspection, including appearance inspection to check whether the sheath surface is smooth, without bubbles and scratches; size measurement of cable outer diameter, insulation and sheath thickness; electrical performance tests including insulation resistance, voltage withstand (applying 1.8kV voltage for 1min without breakdown), partial discharge (≤10pC), etc.; mechanical performance tests of the sheath's tensile strength and elongation at break; flame retardant performance test of bundle burning, which complies with GB/T 18380.3. Only after all tests are qualified, the production batch number and production date are marked before leaving the factory.

The cable is packaged with wooden cable reels, using dried pine wood with a moisture content of ≤15% to avoid deformation during transportation. The diameter of the 500m cable reel for 4×70mm² is 1000mm, 1200mm for 4×95mm², and 1500mm for 4×185mm². The structure of the cable reel includes a reel shaft (diameter 300mm-400mm), baffles (thickness 30mm-40mm) and 8 spokes, ensuring that the load-bearing capacity meets the requirements (≥20kN). The outer layer of the cable is wrapped with a 0.1mm thick polyethylene film, and plastic protective caps (made of ABS) are installed at both ends to prevent water ingress and damage to the ends.

The cable is coiled with uniform tension (3kN-5kN), and each circle is closely arranged without crossing or overlapping. After coiling, 50mm wide steel strips are used to fix both sides of the cable reel with 6 strips on each side, and the joints of the steel strips are locked with buckles to prevent the cable from slipping. Two cast iron lifting rings are installed on the edge of the cable reel, welded firmly, with a load-bearing capacity of ≥10kN. A waterproof label is fixed on the side of the cable reel, indicating the product model, specification, length, weight, production batch number, implementation standard, manufacturer information, etc.

The label is made of wear-resistant PVC material, with text in both Chinese and English. In addition to basic product information, it also prints warning signs such as "Stand upright", "No rolling", "Moisture and sun protection", etc., reminding operators of the precautions with a combination of diagrams and text. Each reel of cable is accompanied by a product certificate and inspection report, detailing various test data.

For short-distance transportation (≤500km), road transportation is adopted, using flatbed trucks with a carriage length of ≥8m, which can load multiple reels of cables. The trucks are equipped with fixing devices such as steel wire ropes and tighteners to ensure the stability of the cable reels. For long-distance transportation (>500km), railway transportation is preferred, and the cable reels are fixed on railway flatcars to reduce by using the stability of the railway. Export products are transported by container shipping, with 2-3 reels of cables loaded in each container, and the interior is fixed with wooden frames to prevent collision during transportation.

During transportation, the cable reel must be placed upright, and the bottom is fixed with

roved. XLPE has excellent electrical insulation performance, which can effectively isolate current leakage between conductors. It has high insulation resistance and low dielectric loss, ensuring the safety of the cable during long-term operation. In addition, XLPE has strong aging resistance, and its service life in underground environments can reach more than 30 years.

The sheath is available in HDPE or PVC. HDPE sheaths have higher impact resistance and chemical corrosion resistance, and excellent low-temperature performance, making them suitable for areas with high groundwater levels and strong soil corrosion; PVC sheaths have better flame retardancy and relatively lower prices, suitable for ordinary soil environments. Both sheaths are added with ultraviolet absorbers and antioxidants to improve weather resistance, and can resist the impact of a small amount of light and temperature changes even in shallow underground.

All three cables have a circular structure, with 4 Cores symmetrically arranged around the center. After compact stranding, a compact cable core is formed, and the outer layer is wrapped with an XLPE insulation layer and a sheath in sequence, with an overall round and smooth structure. The surface of the cable is printed with clear marks, including model specifications (such as XLPE insulated 4×70mm² aluminium core cable), rated voltage, manufacturer, meter marks, etc., which is convenient for identification and cutting during construction. In terms of color, HDPE sheaths are mostly black, and PVC sheaths are available in black and gray, which can blend with the underground environment.

First, aluminum ingots are smelted into aluminum liquid, and aluminum rods with a diameter of 9mm-12mm are made through continuous casting. The aluminum rods are drawn through a wire drawing machine in multiple passes to make Aluminum Wires of the required diameter. During the wire drawing process, a special lubricant is used to avoid scratches on the surface of the Aluminum Wires. Then, according to the cross-sectional specifications, a certain number of aluminum wires are stranded on a compact stranding machine. There are about 120 aluminum wires per core for 4×70mm², about 160 for 4×95mm², and about 280 for 4×185mm². During stranding, the conductor is compacted through a mold, so that the conductor filling coefficient reaches more than 90%, reducing gaps and improving conductivity. After stranding, annealing treatment is performed to eliminate internal stress and enhance the flexibility of the conductor.

The stranded conductor enters the insulation extrusion process. XLPE particles are added to the extruder hopper after drying treatment (moisture content ≤50ppm). The extruder barrel is heated in three sections, with temperatures of 120℃-140℃, 160℃-180℃, and 180℃-200℃ respectively, to melt and plasticize XLPE. The molten XLPE is evenly extruded onto the conductor surface through a cross-head mold to form an insulation layer, and the mold size is precisely designed according to the insulation thickness. The extruded insulated wire core immediately enters a cooling water tank, and the water temperature is controlled at 20℃-30℃ for rapid cooling and shaping. After that, the insulated wire core enters the cross-linking tube, and the cross-linking reaction is completed in a high-pressure steam environment of 180℃-200℃ and 1.5MPa-2.0MPa to form a stable three-dimensional structure.

After passing the inspection, the insulated wire cores enter the cabling machine. The 4 insulated wire cores are stranded into a cable in an S-shaped direction. The cabling pitch of 4×70mm² is 160mm-200mm, 4×95mm² is 200mm-250mm, and 4×185mm² is 250mm-300mm. During the cabling process, polypropylene ropes are filled in the center of the cable core, and asbestos ropes (to enhance flame retardancy) are filled in the gaps to make the cable core round and stable. After cabling, a layer of semi-conductive water-blocking tape is wrapped around the outer layer of the cable core to prevent moisture from infiltrating, and then a layer of non-woven tape is wrapped as an isolation layer.

The cabled core enters the sheath extruder. HDPE or PVC sheath materials are added to the extruder after mixing and plasticizing, and the barrel temperature is controlled at 160℃-190℃ (HDPE) or 150℃-180℃ (PVC). The molten sheath material is extruded onto the surface of the cable core through a mold to form a uniform sheath layer, and the mold is precisely processed according to the outer diameter of the cable. The extruded cable is cooled in sections in a cooling water tank, and the water temperature is gradually reduced from 60℃ to 20℃ to avoid internal stress in the sheath due to sudden cooling. After cooling, the cable is pulled to the take-up machine by a tractor and neatly coiled on the cable reel. The take-up tension is controlled at 5kN-8kN to prevent the cable from stretching and deforming.

The finished cable needs to undergo strict inspection, including appearance inspection to check whether the sheath surface is smooth, free of bubbles and scratches; size measurement of cable outer diameter, insulation and sheath thickness; electrical performance tests including insulation resistance, voltage withstand (applying 1.8kV voltage for 1min without breakdown), partial discharge (≤10pC), etc.; mechanical performance tests of sheath tensile strength and elongation at break; flame retardant performance tests of bundle burning, in line with GB/T 18380.3 standard. All products that pass the tests are marked with production batch numbers and production dates before leaving the factory.

The cable is packaged with wooden cable reels, using dried pine wood with a moisture content of ≤15% to avoid deformation during transportation. The diameter of the 500m cable reel for 4×70mm² is 1000mm, 4×95mm² is 1200mm, and 4×185mm² is 1500mm. The cable reel structure includes a reel shaft (diameter 300mm-400mm), baffles (thickness 30mm-40mm) and 8 spokes, ensuring that the load-bearing capacity meets the requirements (≥20kN). The outer layer of the cable is wrapped with a 0.1mm thick polyethylene film, and both ends are equipped with plastic protective caps (made of ABS) to prevent water and damage to the ends.

The cable is coiled with uniform tension (3kN-5kN), and each circle is closely arranged without cross-overlapping. After coiling, 50mm wide steel strips are used to fix 6 strips on each side of the cable reel, and the steel strip joints are locked with buckles to prevent the cable from slipping. Two cast iron lifting rings are installed on the edge of the cable reel, which are firmly welded and have a load capacity of ≥10kN. A waterproof label is fixed on the side of the cable reel, indicating the product model, specification, length, weight, production batch number, implementation standard, manufacturer information, etc.

The label is made of wear-resistant PVC material, with text in both Chinese and English. In addition to basic product information, it is also printed with warning signs, such as "Stand upright", "No rolling", "Moisture and sun protection", etc., reminding operators of precautions with a combination of diagrams and text. Each reel of cable is accompanied by a product certificate and inspection report, detailing various test data.

For short-distance transportation (≤500km), road transportation is adopted, using flatbed trucks with a carriage length of ≥8m, which can load multiple reels of cables. The truck is equipped with steel wire ropes, tighteners and other fixing devices to ensure the stability of the cable reels. For long-distance transportation (>500km), railway transportation is preferred, and the cable reels are fixed on railway flat cars, using the stability of the railway to reduce. Export products are shipped by container, with 2-3 reels of cables loaded in each container, and the interior is fixed with wooden frames to prevent collision during transportation.

During transportation, the cable reel must be placed upright, and the bottom is fixed with wooden pads to prevent tipping. Buffer materials are placed between the cable reels to avoid mutual collision and damage to the sheath. When loading and unloading, a crane is used, and the lifting belt hooks the special lifting ring. It is strictly forbidden to directly bind the cable body. During transportation, sudden braking and sharp turns are avoided, and the speed is controlled within 60km/h (road). In case of heavy rain, strong wind and other bad weather, stop to check whether the cable reel is damp and whether the fixation is loose, and cover with rainproof cloth if necessary. For long-distance transportation, check once every 200km to ensure the cable is in good condition.

After the customer places an order, the sales department confirms the order information (model, quantity, delivery date, etc.) and generates a delivery note. The warehouse checks the inventory. Products in stock are inspected by the quality inspection department before leaving the warehouse, and packaging is arranged after passing the inspection. For products that need to be produced, the production department formulates a production plan to ensure completion on schedule. After packaging, contact the transportation company to sign a transportation contract, specifying the transportation responsibilities and insurance clauses. When the transportation company picks up the goods, the warehouse and the driver jointly check the product information and quantity, and sign the goods handover form. After delivery, the sales department sends a delivery notice to the customer, including the transportation method, waybill number, estimated arrival time, etc., and provides tracking and query methods.

For products with stock of conventional specifications, delivery will be made within 1-3 working days after receiving the payment. The delivery time of customized products (such as special sheath materials) is determined according to the production cycle, generally 7-15 working days, and the specific time is negotiated with the customer. In case of delay caused by force majeure such as raw material shortage, the customer will be notified 48 hours in advance, and a new delivery time will be negotiated, and corresponding supporting documents will be provided.

Customers can apply for samples through phone calls, emails or online platforms, indicating the required model, specification and quantity. The company will prepare samples within 2 working days after receiving the application. The length of the samples is usually 2m, which can meet the needs of appearance, size and basic performance testing. For longer samples or special tests (such as temperature resistance and corrosion resistance tests), 5m-10m samples can be provided, and the specific length is determined according to customer needs.

Regular samples applied for the first time are free, and the customer bears the freight (collect on delivery is optional). For the same customer applying for the same type of samples again, a sample cost (about 50% of the product unit price) will be charged. Special customized samples are charged according to the processing cost, which can be deducted from the payment after placing an order.

Samples are packaged in hard cartons with foam padding inside to prevent damage during transportation. Domestic samples are delivered by SF Express, arriving within 1-3 days; international samples are delivered by DHL or FedEx, arriving within 5-7 days. After delivery, the courier number is provided, and customers can track the logistics information online. A sample description is attached with the sample, including product parameters, test reports, etc., and technical personnel can provide follow-up testing guidance.

The product warranty period is 3 years (from the date of delivery). During the warranty period, if the product cannot be used due to its own quality problems (such as insulation breakdown, sheath cracking, etc.), the company will provide free replacement of new products or maintenance services. Customers need to provide purchase vouchers, fault photos and detailed descriptions, and technicians will provide solutions within 24 hours. For products damaged by man or beyond the warranty period, paid maintenance services are provided, with reasonable material fees and labor fees charged.

The company has a professional technical team to provide customers with full-process technical support. Pre-sales, it provides selection suggestions, recommending appropriate specifications according to the customer's power load and laying environment; in-sales, it provides laying scheme design, including direct burial depth and protective measures; after-sales, it provides installation guidance, and can solve installation problems through video conferences or on-site guidance. At the same time, it provides product technical manuals, installation guides and other materials to help customers use the products correctly.

When a customer finds a cable fault, they can call the after-sales hotline to report the fault. After-sales personnel will record the fault situation and respond within 1 hour. For simple faults (such as joint problems), technicians can guide customers to check and solve them by phone; for complex faults that require on-site handling, the company will arrange technicians to arrive at the site according to the distance, arriving within 24 hours in the city, 48 hours in the province, and 72 hours outside the province. On-site maintenance