Medium & High Voltage Insulated Power Cables

1. Product Introduction

Medium Voltage (MV) & High Voltage (HV) XLPE insulated power cables are the primary underground power transmission wiring for urban power grids, industrial parks and new energy power stations. Adopting extruded solid insulation instead of air insulation, they enable enclosed safe installation and eliminate faults of overhead lines caused by lightning, ice coating, tree contact and wind swing.

Voltage Classification

• Medium Voltage (MV): 3.6/6kV ~ 26/35kV, widely applied in urban distribution networks and factory power supply

• High Voltage (HV): 64/110kV, 127/220kV, used for regional trunk transmission and interconnection between substations Compliant with Chinese national standards GB/T 12706 (1kV~35kV) and GB/T 11017 (66/110kV), equivalent to international standards IEC 60502 & IEC 60840. Cross-linked polyethylene (XLPE) serves as mainstream insulation material, featuring high temperature resistance, low dielectric loss, corona resistance, moisture-proof and anti-aging properties. Applicable for direct burial, tunnel, cable tray, vertical shaft and underwater laying.

2. Model Definition & Main Types

Code Explanation

YJ = XLPE cross-linked polyethylene insulation; V = PVC sheath; Y = PE sheath; L = aluminum conductor (no L denotes copper conductor); 22 = double steel tape armour + PVC outer sheath; 32 = steel wire armour; WDZ = LSZH flame retardant; WDZN = LSZH fire resistant

Common Models & Applications

1. YJV / YJLVCopper/aluminum core, XLPE insulated, non-armored; for indoor, cable trench and tunnel laying without external mechanical compression

2. YJV22 / YJLV22 (Most widely used)Steel tape armored with compression resistance, suitable for direct underground burial, pipe laying, anti-rodent protection against radial mechanical load

3. YJV32 / YJLV32Steel wire armored with excellent tensile strength, designed for vertical shaft installation, underwater laying and large elevation difference conditions

4. WDZA-YJY23LSZH low-smoke zero-halogen flame retardant type, applied to subways, utility tunnels, hospitals, shopping malls and other fire-critical areas

5. Single-core HV cables (64/110kV, 127/220kV)Large cross-section copper/aluminum conductor with layered shielding structure, used for urban UHV underground trunk lines Core configuration: 3-core dominates for MV cables; single-core exclusively for 110kV and above HV cables; standard cross-section range: 25mm² ~ 1600mm²

3. Internal Structure (3-core MV Cable, From Inner to Outer)

1. ConductorClass 2 compact stranded oxygen-free copper or aluminum; smooth and round surface reduces electric field concentration. Copper conductor delivers larger ampacity and higher reliability; aluminum conductor is lightweight and cost-effective for long-distance distribution.

2. Conductor Semi-conductive ScreenExtruded cross-linked semi-conductive layer covering the conductor seamlessly, smoothing stranded gaps and eliminating electric field distortion to prevent partial discharge insulation breakdown.

3. XLPE Insulation Layer (Core Component)Ultra-clean polyethylene triple co-extruded and cross-linked; insulation thickness increases with voltage grade. Rated continuous temperature 90℃, ultra-low dielectric loss, outstanding corona resistance, waterproof performance, withstand long-term power frequency voltage and switching surge shocks.

4. Insulation Semi-conductive Screen + Copper Tape Metallic ScreenOuter insulation screen equalizes electric potential; wrapped copper tape collects capacitive current, discharges short-circuit fault current via grounding and limits induced voltage to ensure personal safety.

5. Filler & Cabling Wrapping TapePolypropylene filler forms a round cable core; wrapping tape binds three cores integrally to buffer compression and block moisture ingress.

6. Inner Cushion SheathPVC/PE buffer layer separating cable core and armour, preventing metal burrs from piercing insulation.

7. Armour (Optional)

• Steel tape armour (22): Compression resistant, preferred for direct burial

• Steel wire armour (32): Tensile resistant, dedicated to vertical shafts and underwater laying

8. Outer SheathStandard black PVC/PE sheath; HDPE for corrosive environments; LSZH sheath for enclosed fire-proof spaces, resistant to oil, acid, alkali, salt mist and UV aging.

4. Key Technical Parameters

1. Rated Voltage Grades MV: 3.6/6kV, 6/10kV, 8.7/10kV, 21/35kV, 26/35kV HV: 64/110kV, 127/220kV

2. Continuous operating temperature: 90℃ for XLPE insulation; maximum short-circuit temperature (≤5s): 250℃

3. Minimum laying ambient temperature: ≥0℃; customized cold-resistant version down to -40℃

4. Minimum Bending Radius 3-core armored cable: ≥15 times cable outer diameter Single-core HV cable: ≥20~25 times outer diameter

5. Electrical performance: Ultra-low partial discharge, passed power frequency & impulse voltage withstand tests

6. Earthing requirement: Both ends of metallic screen shall be reliably grounded to restrain induced potential and electromagnetic interference

5. Core Performance Advantages

1. Superior power supply reliability vs overhead lines Totally enclosed solid insulation avoids failures caused by rain, snow, lightning, ice, birds and tree branches, drastically cutting fault rates for downtown urban power supply.

2. Excellent electrical performance & low energy loss XLPE insulation features far lower dielectric loss than oil-impregnated cables, less heat generation and larger power transmission capacity, adapting to massive grid integration of renewable energy.

3. Flexible multi-scenario laying Applicable for direct underground burial, utility tunnels, cable trays, high-rise vertical shafts and underwater river crossing, space-saving for densely populated cities with limited land resources.

4. Comprehensive environmental adaptability Moisture-proof, resistant to acid, alkali, salt mist and oil, UV stabilized; optional flame retardant, fire resistant and LSZH types greatly improve safety during fire accidents.

5. Long service life & easy maintenance Design service life reaches 30~50 years under normal operation; matched with cable accessories and online monitoring systems for convenient inspection and fault location.

6. Application Scenarios

1. Urban Municipal Power Grid: 10kV & 35kV urban loop networks, switching stations, incoming & outgoing lines of substations

2. Heavy Industrial Plants: Power distribution for metallurgy, mining, chemical and refinery facilities, variable frequency power for water pumps & fans

3. New Energy Industry: Collector cables for photovoltaic & wind farms, internal high-voltage wiring for energy storage power stations

4. Large Public Buildings: Fire power distribution systems for subways, tunnels, hospitals, airports and shopping malls

5. HV Trunk Transmission: 110kV/220kV urban underground cables, interconnection lines for suburban regional power grids

6. Special Conditions: Underwater river/lake laying, coastal saline-alkali corrosive areas, power grid renovation in frigid regions