ZR-YJV 3x240mm²+1x120mm² XLPE Copper Cable 0.6/1kV Flame Retardant

ZR-YJV 3×240+1×120 mm² — Cable Specification & Engineering Data

1. Product Identity & Ratings. A heavy-duty flame-retardant 3+1-core low-voltage cable, ZR-YJV 3×240+1×120 pairs three 240 mm² copper phase conductors with a single 120 mm² copper neutral, all insulated in XLPE and protected by one ST2 PVC jacket. It is rated 0.6/1 kV (Um = 1.2 kV) at 50 Hz, produced and proof-tested in line with GB/T 12706.1 / IEC 60502-1, stranded per GB/T 3956, and classified ZC under GB/T 19666. Overall diameter is about 53 mm (Tianjin Cable Works 3+1 sample), approximate weight 8950 kg/km for copper (≈ 3720 kg/km for the aluminium YJLV equivalent); standard supply is 100 m coils or wooden drums with ≥ Ø 2000 mm flanges (≈ 895 kg per 100 m).

2. Build-Up from Conductor to Jacket. Layer by layer:

3. Electrical Performance. Phase resistance is capped at 0.0754 Ω/km at 20 °C (rising to ≈ 0.096 Ω/km at the 90 °C operating point), while the 120 mm² neutral is capped at 0.153 Ω/km. Routine factory proof is 3.5 kV AC for 5 min with no breakdown; finished-cable insulation resistance ≥ 36.7 MΩ·km and XLPE volume resistivity ≥ 1×10¹² Ω·cm. Typical capacitance ≤ 0.38 μF/km, inductance ≈ 0.23 mH/km, and AC impedance at 50 Hz ≈ 0.12 Ω/km. The 240 mm² phase withstands ≈ 27.6 kA for 1 s (the 120 mm² neutral on a ≈ 13.8 kA basis). Reference loading, with all three phases energised, is ≈ 560 A in free air at 30 °C and ≈ 470 A buried at 25 °C — a 3+1-series estimate carried forward from the Zhongce basis; note that published 3-core 240 tables cluster around 480–500 A in air, so the factory test certificate should always be consulted for the actual figure.

Electrical Parameters

Cable Parameters

Cable Test Parameters

Cable Cross Section Structure

4. Thermal & Flame Behaviour. The XLPE system permits 90 °C continuous conductor temperature and 250 °C under short-circuit (≤ 5 s). Service ambient ranges from −20 to +45 °C, with a 0 °C minimum laying temperature and 25 °C reference soil temperature for direct burial. Flame performance is class ZC per GB/T 19666, demonstrated by GB/T 18380.12 single-cable and GB/T 18380.35 category-C bunched tests (char height ≤ 2.5 m). Because the PVC jacket is halogenated and generates smoke under fire, WDZ-YJY is the correct choice where low-smoke zero-halogen performance is required.

5. Installation & Handling. Keep bends to at least 15 × OD, i.e. ≈ 795 mm for this size. Before first energisation apply the DC commissioning test at 4U0 = 2.4 kV for 15 min per Q/GDW 13244.1-2018. Drums stored below 0 °C must be warmed before pulling; maximum pulling tension is ≤ 9600 N. The 560/470 A references must be derated for ambient temperature, cable grouping and soil conditions. Terminals and glands should be selected for the 20.2 mm phase core, 14.2 mm neutral core and ≈ 53 mm jacket, and both phase and neutral short-circuit ratings should be checked against the protective device settings.

6. Fields of Application. This cable is intended for the most demanding three-phase four-wire distribution duties: main switchgear incomers, LV transformer secondaries in the ~1600–2000 kVA range, vertical busbar risers in high-rise and commercial buildings, heavy industrial plant feeders, pump and compressor stations, primary feeds to data centres and municipal distribution networks where a dedicated neutral is carried in a single cable (TN-C style). Approved laying methods include conduit, tray, trench, duct, trunking and direct burial with mechanical protection, indoors or in sheltered outdoor locations. For direct burial without added protection specify the steel-tape armoured ZR-YJV22 variant (≈ 63–68 mm OD).

7. Testing & Quality Control. Routine tests on every production length cover phase and neutral DC resistance (≤ 0.0754 / 0.153 Ω/km at 20 °C), the 3.5 kV AC / 5 min power-frequency withstand, conductor continuity and dimensional checks (phase insulation ≥ 1.7 mm, neutral ≥ 1.1 mm, sheath ≥ 3.0 mm, OD ≈ 53 mm). Sample and type tests include the XLPE hot-set test at 200 ± 3 °C for 15 min under 0.2 MPa (load elongation ≤ 175 %, permanent set ≤ 15 %), XLPE tensile ≥ 12.5 MPa with elongation ≥ 200 %, PVC sheath tensile ≥ 10 MPa with elongation ≥ 125 %, PVC thermal stability ≥ 200 min at 200 °C, single-cable and category-C bunched flame tests, and bending tests. On site, insulation resistance, the DC 2.4 kV / 15 min withstand and phase/neutral identification must be completed before switching on. Each drum is accompanied by a factory test certificate.

Flame Retardant Parameters

Insulation Parameters

8. Standards & Regulatory Compliance. Design and manufacture follow GB/T 12706.1 and IEC 60502-1 for 0.6/1 kV extruded-insulation power cables; conductors meet GB/T 3956 / IEC 60228 Class 2 (240 mm² as 61 × 2.25 mm with R ≤ 0.0754 Ω/km; 120 mm² as 19 × 2.83 mm with R ≤ 0.153 Ω/km). Flame retardance is classified under GB/T 19666 (ZC as the default for "ZR") and verified by GB/T 18380.12 and GB/T 18380.35 category C. Installation acceptance follows Q/GDW 13244.1-2018 and GB 50168, and surface marking follows GB/T 6995. Cables can also be supplied to IEC, BS, DIN, ICEA or JIS requirements on request. Remember that the ST2 PVC jacket contains halogen — for tunnels, metros, hospitals and other enclosed public spaces, specify WDZ-YJY.

9. Packaging, Storage & Logistics. Standard lengths are 100 m per coil or wooden drum, with custom cut lengths available. Each drum is marked with type, voltage, manufacturer, year of manufacture and sequential metre marks per GB/T 6995. Store in dry, covered conditions between −20 and +45 °C, away from direct sunlight, moisture, oils and sharp objects; keep drums sealed until installation and stand them on their flanges rather than lying flat. In cold weather, condition drums indoors to ≥ 0 °C before uncoiling and pulling. During transport, secure drums against rolling and impact, and never drag the cable over rough ground or sharp edges.

10. Ordering Information. Specify "ZR-YJV 0.6/1 kV 3×240+1×120" together with the required supply length or drum arrangement and surface marking. State the flame-retardant class (ZC is the default; ZA/ZB on request), jacket colour and any special drum requirements. Always request the manufacturer's factory test certificate to confirm the actual unarmoured OD (≈ 53 mm), weight (≈ 8950 kg/km) and ampacity. For low-smoke zero-halogen or armoured variants, order WDZ-YJY or ZR-YJV22 respectively.

11. Cable Industry FAQ.

• Q1: How do YJV, ZR-YJV, YJV22 and WDZ-YJY differ? YJV is the base XLPE/PVC cable; ZR-YJV adds flame-retardant behaviour (default class ZC); YJV22 adds a steel-tape armour for direct burial and mechanical protection — the 3×240+1×120 armoured build reaches ≈ 63–68 mm; WDZ-YJY replaces the PVC jacket with a halogen-free, low-smoke compound for enclosed public spaces.
• Q2: What do ZA / ZB / ZC / ZD stand for? They are flame-retardant classes under GB/T 19666, verified by the bunched-cable test GB/T 18380.35 at different fuel loads — A is the most stringent, D the least. "ZR" without a letter defaults to ZC; ZA and ZB must be explicitly stated at the order stage.
• Q3: Why is the neutral smaller (120 mm²) than the phase (240 mm²)? In a balanced three-phase circuit the neutral carries mainly unbalance and harmonic current, so GB/T 12706.1 allows a reduced neutral in the 3+1 construction. Where heavy single-phase or non-linear, harmonic-rich loads are expected, choose an equal-section 4-core cable or a larger neutral.
• Q4: When should I use 3+1, 4-core equal, or 3+2? Use 3+1 for general TN-C three-phase four-wire service with a reduced neutral; 4-core equal (3×A+1×A) when neutral current approaches phase current; 3+2 (three phases plus separate N and PE) for TN-S systems that need distinct neutral and protective conductors.
• Q5: Why do air and buried ratings differ, and how are they corrected? The figures assume 30 °C air or 25 °C soil at 1.0 K·m/W thermal resistivity with a single circuit. Apply manufacturer correction factors for ambient temperature, cable grouping, burial depth and soil resistivity — air factors run roughly from 1.29 at 20 °C down to 0.91 at 45 °C, and soil factors from 1.04 at 20 °C to 0.87 at 40 °C.
• Q6: Copper or aluminium conductor? Copper (this cable) gives lower resistance (0.0754 versus ≈ 0.125 Ω/km at 240 mm²), higher ampacity per mm², better mechanical strength and more reliable terminations; aluminium (YJLV, ≈ 3720 kg/km in this size) is cheaper and lighter but requires larger cross-sections and anti-oxidation treatment at joints.
• Q7: Why is XLPE rated 90 °C while PVC insulation is only 70 °C? Cross-linking converts polyethylene into a thermoset network, lifting the continuous conductor temperature to 90 °C and short-circuit tolerance to 250 °C — which directly raises ampacity for the same copper area.
• Q8: How is the conductor size chosen? Size against (a) full-load current with derating factors, (b) permissible voltage drop (typically ≤ 5 % for power circuits), (c) short-circuit withstand on an I²t basis (27.6 kA·s per phase here), and (d) coordination with protective devices; the most onerous requirement governs.
• Q9: Why does finished diameter vary between manufacturers for the same nominal size? Standards fix minimum insulation and sheath thickness plus electrical performance, not exact OD. Stranding compaction, filler design and sheath tolerance differ by plant — published 3×240+1×120 figures cluster around 53 mm unarmoured — so always use the actual measured OD when sizing glands, trays and conduits.
• Q10: Which tests confirm the cable is acceptable on delivery and before energisation? On delivery, verify the factory test certificate (resistance 0.0754/0.153 Ω/km, 3.5 kV/5 min withstand, dimensions ≈ 53 mm), jacket marking and drum condition. After laying, carry out an insulation-resistance test plus the DC 4U0 = 2.4 kV / 15 min withstand per Q/GDW 13244.1-2018, then confirm phase and neutral identification before switching on.
• Q11: What service life can be expected? When installed within the temperature and voltage limits, XLPE 0.6/1 kV cables are designed for ≥ 30 years of service; prolonged overload, UV exposure, water immersion through a damaged jacket, or operation above 90 °C will shorten life materially.