Aluminum XLPE Cable YJLV22 3x70mm² 8.7/15kV Armored MV Power Cable

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)

YJLV22-3×70 mm² 8.7/10 kV (and 8.7/15 kV) — Cable Specification & Engineering Data

1. Product Overview & Rating Summary. YJLV22-3×70 is a large-size medium-voltage (MV) power cable rated 8.7/10 kV (Um = 12 kV) at 50 Hz, built around three 70 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 2500–4000 kVA distribution transformers and MV motors in the 1000–1600 kW range. Finished diameter is about 72 mm (10 kV) and nominal mass about 6200 kg/km (≈ 620 kg per 100 m). With all three cores loaded, the cable carries about 190 A in free air at 25 °C (engineering estimate).

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

3. Electrical Characteristics. Each 70 mm² aluminium conductor is held to a maximum DC resistance of 0.443 Ω/km at 20 °C — about 31% lower resistance than the 50 mm² aluminium version, which translates directly into higher ampacity and lower voltage drop on long MV runs. 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 ≈ 0.66 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 190 A in free air at 25 °C, about 185 A direct-buried.

Insulation Data

Electrical Parameters

Reference values: 70 mm² Al at 165 A, 3-phase 10 kV → max balanced load ≈ 2.86 MVA. Voltage drop at 165 A ≈ 9.3 V/km per core (≈0.093% per 100 m).

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 4.7 kA for the 70 mm² aluminium conductor — about 38% higher than the 50 mm² version, though still well below copper of equivalent cross-section. 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 1080 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 620 kg per 100 m, this is the upper end of man-handleable aluminium cable; drum jacks, winches and rated pulling gear are essential.

Mechanical & Installation Parameters

6. Typical Service Applications. This YJLV22-3×70 aluminium MV cable is the large-size cost-effective choice for 10 kV / 15 kV distribution feeders where mechanical strength and burial protection are needed and loads are heavy: 2500–4000 kVA distribution transformer primary feeds in large industrial parks, suburban commercial districts and county-level trunk networks, 10 kV branch feeds to large industrial plants and workshops, MV motor branch feeds for motors in the 1000–1600 kW range (very large pumps, fans, compressor stations, mill drives), township and county 10 kV overhead-to-underground transition feeders, high-rise commercial and hospital 10 kV incoming mains, municipal water-supply and wastewater 10 kV supply mains, large PV / solar-farm 10 kV collection mains, mining and quarry 10 kV heavy-duty power supply lines, 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 ≤ 0.443 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-3×70" (or "YJLV22-8.7/15 kV-3×70" 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: How does 70 mm² aluminium compare to 50 mm² aluminium? 70 mm² raises the reference ampacity from about 150 A to about 190 A (+27%), and lowers the DC resistance from 0.641 Ω/km to 0.443 Ω/km (−31%). It is the standard upgrade when the load grows beyond the 1600–2500 kVA transformer band and enters the 2500–4000 kVA range. The armour also steps up from 2×0.3 mm to 2×0.5 mm steel tape and the jacket from 2.2 mm to 2.4 mm. Weight rises from 4800 to 6200 kg/km, still far lighter than an equivalent copper cable.
• Q2: 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 heavily-loaded suburban, industrial-park and rural distribution feeders, YJLV22 remains the standard cost-optimised choice.
• Q3: 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.
• Q4: 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.
• 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 70 mm² aluminium, the 1 s short-circuit rating is about 4.7 kA — higher than 50 mm² but still well below 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 95 or 120 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.