ZR-YJV 3x300mm²+1x150mm² XLPE Copper Cable 0.6/1kV Flame Retardant

ZR-YJV 3×300+1×150 mm² — Cable Specification & Engineering Data

1. Product Definition & Rating Framework. Sitting at the top of the conventional flame-retardant 3+1-core catalogue, ZR-YJV 3×300+1×150 combines three 300 mm² copper phase conductors with a dedicated 150 mm² copper return conductor, each insulated in XLPE and jointly protected by a single ST2 PVC oversheath. The cable is engineered for 0.6/1 kV systems (Um = 1.2 kV) at 50 Hz, manufactured and verified against GB/T 12706.1 / IEC 60502-1, stranded in accordance with GB/T 3956, and marked ZR to denote class ZC flame retardance under GB/T 19666. Overall diameter measures approximately 57 mm (Beijing Jiaotai Cable sample), with a nominal weight of 11155 kg/km in copper construction — the aluminium YJLV equivalent comes in at roughly 4440 kg/km. Supply format is 100 m coils or wooden drums fitted with ≥ Ø 2000 mm flanges, each 100 m drum weighing about 1116 kg.

Cable Designation & Meaning

2. Layered Build-Up (Conductor to Jacket).

3. Electrical Characteristics. The 300 mm² phase conductor is limited to 0.0601 Ω/km at 20 °C, rising to around 0.0766 Ω/km when the conductor reaches its 90 °C operating point; the 150 mm² neutral is capped at 0.124 Ω/km. Every production length passes a 3.5 kV AC power-frequency proof held for five minutes without breakdown. Finished-cable insulation resistance stays above 36.7 MΩ·km, XLPE volume resistivity exceeds 1×10¹² Ω·cm, and typical values include capacitance ≤ 0.42 μF/km, inductance ≈ 0.22 mH/km and 50 Hz AC impedance ≈ 0.10 Ω/km. Under a one-second short circuit the phase conductor can carry approximately 34.5 kA (the 150 mm² neutral on a 17.3 kA basis), calculated from I = k·A/√t with k = 115 for copper/XLPE. Reference loading, with three phase cores in service, is 570 A in open air at 25 °C and 445 A directly buried at 25 °C — figures taken from the Beijing Jiaotai Cable 3+1 table; always cross-check against the manufacturer's test certificate for the actual production batch.

Electrical Parameters

Cable Parameters

Test Parameters

Cable Cross Section Structure

4. Thermal Behaviour & Flame Performance. XLPE permits a sustained conductor temperature of 90 °C and a short-circuit peak of 250 °C for durations not exceeding five seconds. The cable is designed for service ambients between −20 and +45 °C, should not be laid below 0 °C without pre-warming, and uses 25 °C as the reference soil temperature for buried ratings. Flame behaviour meets class ZC of GB/T 19666, demonstrated by both the single-cable vertical test (GB/T 18380.12) and the category-C bunched test (GB/T 18380.35) with char height limited to 2.5 m. The PVC jacket is halogenated and will emit smoke and acid gas in a fire; projects requiring low-smoke zero-halogen performance must specify WDZ-YJY instead.

5. Installation Practice & Handling. Bends must not fall below 15 times the actual outer diameter — approximately 855 mm for this size. Prior to first energisation, apply the DC site withstand at 4U0 = 2.4 kV for 15 minutes in line with Q/GDW 13244.1-2018. Drums held in cold storage below 0 °C must be brought up to temperature before uncoiling; pulling tension should be kept within 12000 N. The 570 A (air) and 445 A (buried) references require derating whenever ambient temperature, cable grouping or soil thermal resistivity deviates from the reference conditions. Crimp lugs, glands and heat-shrink termination kits must be selected for the 20.6 mm phase core, 15.8 mm neutral core and ≈ 57 mm jacket, and both phase and neutral short-circuit withstand should be coordinated with the upstream protective device settings.

6. Typical Service Environments. This cross-section is chosen for the most demanding three-phase four-wire distribution roles: primary incomers to large low-voltage switchboards, transformer secondaries in the 2000–2500 kVA range, vertical rising mains in tall commercial and residential buildings, heavy industrial plant feeders serving large motors and process lines, primary power feeds to data halls and hospital essential systems, and municipal distribution substations where a combined neutral is carried in one cable (TN-C topology). Approved installation methods include conduit, cable tray, trench, duct bank, trunking and direct burial with mechanical protection, both indoors and in covered outdoor locations. For unprotected direct burial the steel-tape armoured ZR-YJV22 variant (≈ 65–70 mm OD) is the correct choice.

7. Testing & Quality Assurance Regime. Routine tests applied to every length include phase and neutral DC resistance verification (≤ 0.0601 / 0.124 Ω/km at 20 °C), the 3.5 kV AC / 5 min withstand, conductor continuity checks and dimensional inspection covering phase insulation ≥ 1.8 mm, neutral insulation ≥ 1.4 mm, sheath ≥ 3.1 mm and overall diameter ≈ 57 mm. Sample and type tests comprise the XLPE hot-set trial at 200 ± 3 °C for 15 minutes 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 minutes at 200 °C, single-cable and category-C bunched flame trials, and bending assessment. Commissioning on site requires insulation-resistance measurement, the DC 2.4 kV / 15 min withstand and positive phase/neutral identification before switching. A factory test certificate accompanies each drum.

Flame Retardant Parameters

Insulation Parameters

8. Standards & Conformity. Design and production are governed by GB/T 12706.1 and IEC 60502-1 for 0.6/1 kV extruded-insulation power cables. Conductors satisfy GB/T 3956 / IEC 60228 Class 2 — the 300 mm² phase as 61 wires of 2.52 mm with R ≤ 0.0601 Ω/km, and the 150 mm² neutral as 37 wires of 2.25 mm with R ≤ 0.124 Ω/km. Flame retardance is classified under GB/T 19666 (ZC as the default for the ZR marking) and proven by GB/T 18380.12 and GB/T 18380.35 category C. Installation acceptance follows Q/GDW 13244.1-2018 and GB 50168, while surface marking complies with GB/T 6995. Cables can also be supplied to IEC, BS, DIN, ICEA or JIS requirements on request. Note that the ST2 PVC jacket contains halogen — for tunnels, metro systems, hospitals and other confined public areas, WDZ-YJY is the appropriate specification.

9. Packaging, Storage & Logistics. Standard delivery is 100 m per coil or wooden drum, with bespoke cut lengths available on request. Each drum carries type, voltage, manufacturer, production year and sequential metre marking per GB/T 6995. Storage should be in dry, covered premises at −20 to +45 °C, shielded from direct sunlight, moisture, oils and sharp objects; drums remain sealed until installation and are stored upright on their flanges rather than flat. In cold conditions, condition drums indoors to ≥ 0 °C before pulling. During transit, drums must be secured against rolling and impact, and the cable must never be dragged across abrasive ground or sharp edges.

10. Procurement Specification. State "ZR-YJV 0.6/1 kV 3×300+1×150" together with the required length or drum arrangement and marking preferences. Specify the flame-retardant class (ZC is standard; ZA or ZB available), jacket colour and any special drum requirements. Always request the factory test certificate to confirm the actual unarmoured diameter (≈ 57 mm), weight (≈ 11155 kg/km) and ampacity for the production batch. Where low-smoke zero-halogen or armoured construction is needed, order WDZ-YJY or ZR-YJV22 respectively.

11. Cable Industry FAQ.

• Q1: What distinguishes YJV, ZR-YJV, YJV22 and WDZ-YJY from one another? YJV denotes the base XLPE-insulated PVC-sheathed cable; ZR-YJV adds flame-retardant properties (class ZC by default); YJV22 introduces a steel-tape armour between the assembly and sheath for direct burial and mechanical robustness — the 3×300+1×150 armoured build reaches roughly 65–70 mm; WDZ-YJY substitutes a halogen-free, low-smoke sheath for the PVC, intended for enclosed public spaces.
• Q2: What is the meaning of ZA, ZB, ZC and ZD? These are flame-retardant classes defined in GB/T 19666, assessed through the bunched-cable test GB/T 18380.35 at progressively higher fuel loads — ZA is the most demanding, ZD the least. The bare "ZR" marking defaults to ZC; ZA and ZB must be explicitly requested at the order stage.
• Q3: Why is the neutral conductor only 150 mm² when the phases are 300 mm²? In a balanced three-phase network the neutral carries primarily unbalance and harmonic current, so GB/T 12706.1 permits a reduced neutral in the 3+1 construction. If the installation serves substantial single-phase or non-linear, harmonic-generating loads, an equal-section 4-core cable or an enlarged neutral should be considered.
• Q4: When should a 3+1, 4-core equal, or 3+2 cable be selected? Choose 3+1 for standard TN-C three-phase four-wire service with a reduced neutral; 4-core equal (3×A+1×A) where neutral current is expected to approach phase current; 3+2 (three phases plus separate neutral and protective conductors) for TN-S installations requiring distinct N and PE paths.
• Q5: Why do air and buried current ratings differ, and how are they adjusted? Published figures assume 25 °C air or 25 °C soil at 1.0 K·m/W thermal resistivity with a single circuit. Manufacturer correction factors must be applied for ambient temperature, cable grouping, burial depth and soil resistivity — air factors range from about 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) delivers lower resistance (0.0601 versus roughly 0.100 Ω/km at 300 mm²), higher current per mm², superior mechanical strength and more dependable terminations; aluminium (YJLV, ≈ 4440 kg/km in this size) costs less and weighs far less but demands larger cross-sections and anti-oxidation treatment at every joint.
• Q7: Why can XLPE operate at 90 °C while PVC insulation is limited to 70 °C? The cross-linking process transforms polyethylene into a three-dimensional thermoset network, which raises the continuous conductor rating to 90 °C and the short-circuit withstand to 250 °C — directly boosting the ampacity available from a given copper area.
• Q8: How is the conductor cross-section determined? Selection is governed by (a) full-load current after applying derating factors, (b) permissible voltage drop (typically ≤ 5 % for power circuits), (c) short-circuit withstand on an I²t basis (34.5 kA·s per phase here), and (d) coordination with overcurrent protective devices; the most stringent criterion controls.
• Q9: Why does finished diameter vary between manufacturers for the same nominal size? Standards mandate minimum insulation and sheath thicknesses together with electrical performance, but not a precise overall diameter. Stranding compaction, filler design and sheath tolerance differ between plants — published 3×300+1×150 figures cluster around 57 mm unarmoured — so the actual measured diameter should always be used when sizing glands, trays and conduits.
• Q10: Which tests confirm acceptability on delivery and before energisation? At delivery, verify the factory test certificate (resistance 0.0601/0.124 Ω/km, 3.5 kV/5 min withstand, dimensions ≈ 57 mm), jacket legibility and drum integrity. After installation, complete 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 closing the breaker.
• Q11: What service life can be expected? When installed and operated within the stated temperature and voltage limits, XLPE 0.6/1 kV cables are designed for a minimum service life of 30 years; sustained overload, ultraviolet exposure, water ingress through a damaged sheath, or operation above 90 °C will materially reduce that lifespan.