Factory-Direct Supply of Certified Wires and Conductors for Diverse Industrial Applications
Three Core 26/35KV Medium Voltage Unarmored Cable
Voltage: 26/35kV (Um=42kV)
Conductor: Copper or aluminum, compacted circular Class 2
Conductor Screen: Extruded semi-conductive compound (per core)
Insulation: XLPE, 10.5mm per core
Insulation Screen: Extruded semi-conductive compound + Cu tape screen
Assembly: 3 screened cores + filler + binder tape
Outer Sheath: PVC Type ST2, PE, or LSZH (BS 7835)
Product Overview
Three Core 26/35kV (Um=42kV) Medium Voltage Unarmoured Cable is the highest-rated three-core XLPE insulated power cable in the commercial MV/HV product range. At 10.5mm of insulation per core — the thickest of any three-core unarmoured cable — it is engineered for 35kV distribution systems where the neutral earthing method subjects healthy phases to elevated phase-to-ground voltage during earth faults. In resistance-earthed or unearthed (isolated) neutral systems, a single-phase earth fault causes the two healthy phases to rise to full phase-to-phase voltage (35kV). The 26kV U₀ rating provides the necessary 24% safety margin over the 21kV class to handle this condition without accelerated insulation ageing — a critical consideration in industrial MV networks and generator auxiliary systems where continuous operation during a single earth fault is required by operational policy.
21/35kV vs 26/35kV: U₀ Matters for System Earthing
Cable Construction
1. Conductor — Stranded compacted circular copper or aluminium
2. Conductor Screen — Extruded semi-conductive compound
3. Insulation — XLPE, 10.5mm, 90°C rated
4. Insulation Screen — Extruded semi-conductive compound
5. Metallic Screen — Copper tape or concentric copper wires
6. Binder Tape — Non-hygroscopic
7. Filler — Non-hygroscopic
8. Outer Sheath — PVC Type ST2 (PE or LSZH)
Technical Characteristics
| Rated Voltage U₀/U (Um) | 26/35kV (42kV maximum system voltage) |
| Governing Standard | IEC 60840 (cables 30kV to 150kV) |
| Insulation Thickness | 10.5mm per core (all cross-sections) |
| Max. Conductor Temperature | 90°C (continuous), 250°C (short-circuit, max 5s) |
| Min. Bending Radius | 15 × overall diameter |
| Conductor Types | Copper or aluminium, compacted circular Class 2 per IEC 60228 |
| Sheath Options | PVC Type ST2, PE, or LSZH (BS 7835) |
| PD Test Voltage | 1.5U₀ (39kV) per IEC 60840 with extinction voltage measurement |
Applicable Standards
| Standard | Scope |
|---|---|
| IEC 60840 | Power cables with extruded insulation for rated voltages above 30kV up to 150kV. 26/35kV (Um=42kV) is governed by this standard. |
| GB/T 12706.2 | Chinese national standard for power cables 6kV to 35kV. 26/35kV is the highest voltage class in this standard. |
| BS 6622 | British standard for XLPE insulated cables. 26/35kV three-core covered under Part 1. |
| BS 7835 | LSZH sheathed MV/HV cables for fire-sensitive indoor installations. |
| IEC 60228 | Conductors — Class 2 stranded copper and aluminium, compacted circular. |
Technical Specifications — Three Core 26/35kV
XLPE insulation: 10.5mm (all cross-sections). Ampacity values pre-calculated for three-core bundle. Air: 30°C. Soil: 20°C, 2.5 K·m/W, 0.7m depth. Conductor range starts at 50mm² for this voltage class.
| Cross Section (mm²) | Conductor Dia. (mm) | Insulation (mm) | Sheath (mm) | Overall Dia. (mm) | Weight Cu (kg/km) | Weight Al (kg/km) | Ampacity Air Cu | Al (A) | Ampacity Soil Cu | Al (A) |
|---|---|---|---|---|---|---|---|---|
| 3 × 50 | 8.4 | 10.5 | 3.5 | 78.5 | 5,842 | 4,909 | 180 | 140 | 190 | 145 |
| 3 × 70 | 10.0 | 10.5 | 3.6 | 82.2 | 6,724 | 5,418 | 220 | 170 | 230 | 180 |
| 3 × 95 | 11.5 | 10.5 | 3.7 | 85.7 | 7,754 | 5,982 | 265 | 205 | 275 | 215 |
| 3 × 120 | 13.0 | 10.5 | 3.9 | 89.1 | 8,786 | 6,547 | 305 | 235 | 315 | 245 |
| 3 × 150 | 14.5 | 10.5 | 4.0 | 92.6 | 9,957 | 7,159 | 345 | 270 | 355 | 275 |
| 3 × 185 | 16.2 | 10.5 | 4.1 | 96.5 | 11,304 | 7,853 | 390 | 305 | 400 | 310 |
| 3 × 240 | 18.4 | 10.5 | 4.2 | 101.5 | 13,302 | 8,825 | 455 | 355 | 460 | 360 |
| 3 × 300 | 20.5 | 10.5 | 4.4 | 106.4 | 15,421 | 9,824 | 525 | 410 | 520 | 410 |
| 3 × 400 | 23.5 | 10.5 | 4.6 | 113.3 | 18,814 | 11,352 | 600 | 470 | 590 | 465 |
Packaging & Delivery
Heavy-Duty Iron-Reinforced Drum
Reinforced wooden or steel drums. 3×400mm² Cu cable approaches 19 tonnes/km. Crane offloading mandatory at factory and site.
Triple-Layer Moisture Protection
Per-core heat-shrink sealing + overall sheath end sealing + dual-layer caps with desiccant. UV-resistant drum wrap for outdoor storage up to 12 months.
IEC 60840 Documentation
Per-core PD certificate (1.5U₀ = 39kV with extinction voltage), AC voltage test (2.5U₀ = 65kV/30min), DC resistance, full traceability.
Typical Applications — Three Core 26/35kV
Resistance-Earthed Industrial 35kV Systems
Primary application. Industrial MV networks with neutral earthing resistors (NER) where U₀=26kV is mandatory for earth fault operation.
Generator Auxiliary Systems
Power station auxiliary 35kV networks where generator ratings exceed 50MW and stability during earth faults requires 26/35kV rated cables.
Chinese GB/T 12706.2 35kV Projects
Specified for 35kV infrastructure projects where system earthing analysis confirms resistance earthing or where project standards mandate the higher U₀ rating.
High-Reliability Substation Connections
132/35kV or 110/35kV substation interconnectors where continuous operation during a single earth fault is a contractual reliability requirement.
Mining 35kV Distribution
Underground and open-pit mining 35kV networks with high earth fault risk due to cable damage likelihood. 26/35kV rating avoids cable replacement after fault-induced overvoltage.
Russian & CIS Heavy Industry
Standard for Russian industrial 35kV networks where system earthing practices and cold climate operational requirements demand the highest U₀ rating available in three-core format.
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Frequently Asked Questions
As a factory, we offer flexible MOQ depending on the cable type. For standard stock items, MOQ is low; for customized specifications, please contact our sales team for a detailed quote.
Yes, Qiangli cables are manufactured in compliance with international standards such as UL, CE, TUV, and VDE. We provide full test reports and certificates upon request.
Absolutely. We have a dedicated R&D team that can customize cable structure, material, color, and printing to meet your specific project needs.
For standard products, lead time is usually 7-15 days. For large-scale project orders or customized products, it typically ranges from 20 to 30 days.
Yes, we provide free samples for most standard cables. You only need to cover the international courier costs. Contact us to arrange your sample shipment.