Aluminum Conductor XLPE Cable 3 Core 25mm² YJLV22 8.7/10kV Armored

Cable Designation & Meaning

Construction: XLPE insulated, aluminium conductor, steel-tape armoured, PVC sheathed, three-core medium-voltage power cable.

Applicable Standards

• GB/T 12706.2-2020 / IEC 60502-2 — Power cables with extruded insulation and their accessories for rated voltages from 6 kV up to 30 kV
• GB/T 3956 / IEC 60228 — Conductors (Class 2 stranded circular, aluminium)
• GB/T 2951 / IEC 60811 — Insulating and sheathing materials — Common test methods
• GB/T 3048 — Test methods for electric cables
• GB/T 18380 / IEC 60332 — Flame retardant tests (Category C or B available)

YJLV22-3×25 mm² 8.7/10 kV (and 8.7/15 kV) — Cable Specification & Engineering Data

1. Product Overview & Rating Summary. YJLV22-3×25 is a compact medium-voltage (MV) power cable rated 8.7/10 kV (Um = 12 kV) at 50 Hz, built around three 25 mm² compacted-stranded ALUMINIUM conductors, each with a triple-extruded semi-conducting screen / XLPE insulation / semi-conducting screen system, a lapped copper-tape screen, and an overall double-galvanised-steel-tape armour (type 22) with a black PVC outer jacket. The "L" in YJLV22 distinguishes the aluminium conductor from the copper YJV22 — same insulation and armour system, but at roughly one-third the weight and one-third the conductor cost. The same construction is also manufactured in the 8.7/15 kV grade (Um = 17.5 kV) with thicker 5.5 mm XLPE insulation. The cable is designed for 10 kV distribution feeders serving 500–1000 kVA distribution transformers and small-to-medium MV motors in the 200–400 kW range. Finished diameter is about 55 mm (10 kV) and nominal mass about 2900 kg/km (≈ 290 kg per 100 m). With all three cores loaded, the cable carries about 95 A in free air at 25 °C (engineering estimate).

2. Layer-by-Layer Construction (Conductor to Outer Jacket).

3. Electrical Characteristics. Each 25 mm² aluminium conductor is held to a maximum DC resistance of 1.20 Ω/km at 20 °C — about 60% higher than a copper conductor of the same cross-section, which is why aluminium cables are typically upsized one or two cross-section steps to match copper ampacity. Every length survives the routine 21.5 kV AC power-frequency proof held for five minutes (30.5 kV for the 15 kV grade). Partial discharge at 1.5 U0 must not exceed 20 pC. Dissipation factor tan δ ≤ 0.001 at U0. Insulation resistance ≥ 1000 MΩ·km, typical capacitance ≈ 0.55 μF/km. Impulse withstand (BIL) is 75 kV for the 10 kV grade and 95 kV for the 15 kV grade. With all three cores energised, reference loading is about 95 A in free air at 25 °C, about 90 A direct-buried.

Insulation Data

Electrical Parameters

Reference values: 25 mm² Al at 90 A, 3-phase 10 kV → max balanced load ≈ 1.56 MVA. Voltage drop at 90 A ≈ 13.8 V/km per core (≈0.138% per 100 m) — significant voltage drop, consider larger size.

Temperature Characteristics

4. Thermal Response & Flame Behaviour. XLPE insulation sustains a 90 °C continuous conductor temperature, with short-circuit capability up to 250 °C for ≤ 5 s. The cable is rated for service ambients between −20 and +50 °C. PVC jacket provides flame-retardant performance per GB/T 18380.34 class A. Short-circuit rating at 250 °C for 1 s is about 1.7 kA for the 25 mm² aluminium conductor — significantly lower than an equivalent copper core, so fault-current protection must be co-ordinated. Thermal resistance of reference burial soil is 1.2 K·m/W.

Fire Performance (YJLV22 — Standard)

5. Installation Practice & Handling. Bends must not fall below 15 times the actual outer diameter — about 825 mm for this size. The steel armour must be earthed at both ends; the copper-tape screen must be bonded per MV practice. Critically, the aluminium conductors must be terminated with bimetallic Al-Cu lugs — direct contact between aluminium and copper in the presence of moisture causes galvanic corrosion and joint failure. MV heat-shrink or cold-shrink termination kits are mandatory. Laying temperature must not fall below 0 °C. At about 290 kg per 100 m, this lightweight cable can be man-handled on site, but the softer aluminium conductor is more prone to kinking — avoid tight pulls and ensure proper drum rotation.

Mechanical & Installation Parameters

6. Typical Service Applications. This YJLV22-3×25 aluminium MV cable is the cost-effective choice for 10 kV / 15 kV distribution feeders where mechanical strength and burial protection are needed but the load is moderate: 500–1000 kVA distribution transformer primary feeds in suburban and rural networks, 10 kV branch feeds to small industrial plants and workshops, MV motor branch feeds for motors in the 200–400 kW range (small pumps, fans, compressors), township and rural 10 kV overhead-to-underground transition feeders, residential-commercial estate 10 kV incoming mains, municipal lighting and water-supply 10 kV supply lines, small PV / solar-farm 10 kV collection laterals, mining auxiliary 10 kV power supplies, and any circuit where the lightweight aluminium conductor reduces installation and support-structure costs relative to copper. Approved installation methods include direct burial, cable tray, concrete duct, and indoor MV cable trench.

7. Testing & Quality Assurance Regime. Routine tests on every length include conductor DC resistance ≤ 1.20 Ω/km at 20 °C, the 21.5 kV AC / 5 min withstand (30.5 kV for 15 kV grade), partial discharge ≤ 20 pC at 1.5 U0, tan δ ≤ 0.001, insulation resistance ≥ 1000 MΩ·km, conductor continuity across all three cores, steel-armour and copper-screen continuity, and dimensional inspection. Sample and type tests comprise impulse withstand at ±75 kV (or ±95 kV for 15 kV), heating-cycle load-loss test, bending at 15 × OD, short-circuit to 250 °C, flame spread GB/T 18380.34 class A, and voltage re-test after thermal ageing. A factory test certificate accompanies each drum.

Cable Parameters

Cable Test Parameters

Cable Cross Section Structure

Cable Construction Description

8. Factory Advantages

9. Packaging, Storage & Logistics. Standard delivery is 500 m or 1000 m per wooden-steel drum, with bespoke cut lengths available on request. Each drum carries type (YJLV22), voltage, size, supplier identity, production year and sequential metre marking per GB/T 6995. Storage should be in dry, covered premises at −20 to +40 °C, shielded from direct sunlight and moisture; drum end seals must remain intact until installation. MV cable terminations and joints should be scheduled immediately after laying to avoid prolonged exposure of the cut aluminium ends.

10. Procurement Specification. State "YJLV22-8.7/10 kV-3×25" (or "YJLV22-8.7/15 kV-3×25" for the thicker-insulation grade) together with the required length or drum arrangement. Always order bimetallic Al-Cu lugs and MV termination kits at both ends — do not substitute pure copper lugs on aluminium conductors. Always request the factory test certificate, which must include the partial-discharge and impulse-withstand reports, to confirm the actual diameter, weight and conductor resistances for the production batch.

11. Cable Industry FAQ.

• Q1: Why choose aluminium (YJLV22) over copper (YJV22)? Aluminium costs roughly one-third of copper per metre at the same cross-section and weighs roughly one-third, which reduces both material cost and installation labour for long MV runs. The trade-off is higher resistance — for the same ampacity you typically need to upsize by one or two cross-section steps. For lightly-loaded rural or suburban distribution feeders, YJLV22 is the standard cost-optimised choice.
• Q2: What does the "L" in YJLV22 mean? "L" = aluminium conductor. Without the L, YJV22 uses copper. The "22" still means double-steel-tape armour over PVC jacket — identical mechanical and fire protection.
• Q3: Why must I use bimetallic lugs? Aluminium and copper form a galvanic cell when directly connected in the presence of moisture. Over years this corrodes the aluminium at the joint, increasing resistance and eventually overheating. Bimetallic Al-Cu lugs have an aluminium barrel on the conductor side and a copper flange on the equipment side, isolating the two metals.
• Q4: How does 3×25 Al compare to 3×25 Cu in ampacity? At 25 mm², the aluminium version carries about 95 A in free air versus about 120 A for copper — roughly 25% less. To match 120 A you would typically choose a 35 or 50 mm² aluminium cable.
• Q5: When do I choose 8.7/10 kV vs 8.7/15 kV? Choose 8.7/10 kV for nominal 10 kV distribution networks (Um = 12 kV). Choose 8.7/15 kV for nominal 15 kV networks (Um = 17.5 kV) or where the system may be up-rated — the thicker 5.5 mm XLPE gives a larger safety margin.
• Q6: Why is there no separate neutral core? At MV distribution voltages, three-phase currents are balanced and the system is typically solidly or resistance-earthed; the copper-tape screen provides the earth path. A separate neutral is not required in standard 3-core MV construction.
• Q7: Can this cable be directly buried? Yes — the double-steel-tape armour provides crush protection, and the PVC jacket is moisture-resistant. Direct burial depth and covering must follow the local MV cable installation code.
• Q8: What is partial discharge and why is it tested? Partial discharge (PD) is tiny electrical sparks inside the insulation caused by voids or contaminants. At 1.5 U0, PD must be ≤ 20 pC. High PD values predict early insulation failure and are the most sensitive factory-quality indicator.
• Q9: Why is the routine test 21.5 kV and not 10 kV? Routine tests apply a power-frequency withstand voltage higher than the rated voltage (typically 2.5 U0 = 21.75 kV, rounded to 21.5 kV) to catch manufacturing defects before site installation.
• Q10: Is the short-circuit rating adequate? At 25 mm² aluminium, the 1 s short-circuit rating is about 1.7 kA — much lower than copper because of aluminium's lower melt point and higher resistance. Protection devices (fuses, breakers) must be sized to clear faults below this level; for high-fault-level networks, upsizing to 35 or 50 mm² aluminium is recommended.
• Q11: What service life can be expected? When installed, terminated and operated within the stated temperature, voltage and current ratings, XLPE-insulated MV cables — aluminium or copper — are designed for a service life of around 30 years in fixed installation. The dominant failure mode is moisture or PD at terminations, so professional jointing and proper bimetallic lugs are critical.