NF C 33-226 Hta Cis 12/20kv 3X240mm Mv Cable

Electrical performance under normal and fault conditions

Mechanical strength and durability

Resistance to environmental factors

Safety in installation and operation

Fire performance and smoke emission

Type Tests: Conducted once per cable design to verify compliance with all standard requirements, including:

Power frequency voltage tests (dry and wet)

Impulse voltage tests

Partial discharge measurements

Thermal aging tests

Short-circuit tests

Mechanical tests (tensile, bending, impact)

Factory Tests: Performed on each production batch to ensure consistent quality:

Conductor resistance measurement

Insulation resistance measurement

Power frequency voltage test at 1.73 times the rated voltage

Visual inspection of dimensions and surface quality

Additional Certifications: Depending on application requirements, the cable may also hold certifications from:

IEC (International Electrotechnical Commission)

CENELEC (European Committee for Electrotechnical Standardization)

Local authorities for specific infrastructure projects

Copper Conductors:

Material: High-purity electrolytic copper (99.95% purity) with a conductivity of 100% IACS (International Annealed Copper Standard) at 20°C.

Stranding: Class 2 stranding (flexible) consisting of 61 strands of 2.2mm diameter Copper Wire, twisted in a concentric lay pattern with a lay length of 12-16 times the conductor diameter.

Mechanical Properties:

Tensile strength: 200-250MPa

Elongation at break: ≥10%

Weight per conductor: 2.15kg/m

Advantages: Superior conductivity, excellent corrosion resistance, and higher mechanical strength, making it ideal for applications where space is limited or high current density is required.

Aluminum Conductors:

Material: 1350 series aluminum alloy (99.5% purity) with a conductivity of 61% IACS at 20°C.

Stranding: Similar to Copper Conductors, with 61 strands of 2.8mm diameter Aluminum Wire.

Mechanical Properties:

Tensile strength: 160-180MPa

Elongation at break: ≥8%

Weight per conductor: 0.65kg/m (30% of copper weight for equivalent current capacity)

Advantages: Significantly lighter weight reduces installation costs and structural load requirements; lower material cost provides economic benefits for large-scale projects.

Inner Semiconducting Layer:

Material: Carbon black-filled ethylene propylene rubber (EPR) with a volume resistivity of 50-100Ω·cm.

Thickness: 1.0mm, applied directly over the conductor.

Function: Eliminates air gaps between the conductor and insulation, ensuring uniform electric field distribution and preventing partial discharges. It also serves as a stress relief buffer at conductor irregularities.

XLPE Insulation:

Material: Cross-linked polyethylene produced using the peroxide cross-linking method, creating a three-dimensional molecular structure.

Thickness: 2.2mm for 12/20kV rating, with a tolerance of ±0.1mm to ensure consistent dielectric performance.

Key Properties:

Dielectric strength: ≥25kV/mm

Volume resistivity: ≥10¹⁴Ω·cm at 20°C

Maximum continuous operating temperature: 90°C

Maximum short-circuit temperature: 250°C for 5 seconds

Manufacturing Process: Extruded over the inner semiconducting layer in a continuous process, followed by cross-linking in a vulcanization tube at 200-250°C. This ensures complete bonding between layers and eliminates voids that could cause electrical breakdown.

Outer Semiconducting Layer:

Material: Similar to the inner layer but with higher carbon black content (volume resistivity 20-50Ω·cm) for improved conductivity.

Thickness: 0.8mm, applied over the XLPE insulation.

Function: Provides a smooth transition between the insulation and metallic screen, distributing electrical stress evenly and preventing corona discharge. It also acts as a moisture barrier and facilitates bonding with the metallic screen.

Metallic Screen:

Material: Tinned copper wires with a diameter of 0.5mm, applied in a spiral around the outer semiconducting layer.

Coverage: 100% coverage with a lay length of 10-15 times the cable diameter.

Electrical Continuity: All copper wires are bonded together at both ends to ensure low resistance and effective fault current handling.

Function:

Contains the electric field within the cable, preventing interference with nearby communication lines.

Provides a low-impedance path for fault currents to flow to ground.

Acts as a shield against external electromagnetic fields.

Galvanized Steel Tape Armor:

Material: Hot-dip galvanized steel tape with a thickness of 0.3mm and width of 25mm.

Application: Applied in a spiral with 15-20% overlap to ensure complete coverage.

Mechanical Properties:

Tensile strength: ≥350MPa

Zinc coating weight: ≥100g/m² for corrosion resistance

Function: Provides mechanical protection against crushing, impact, and abrasion during installation and operation, particularly in underground and duct environments.

Material Options:

PVC (Polyvinyl Chloride): For general applications, featuring:

Shore hardness: 85±5

Tensile strength: ≥15MPa

Elongation at break: ≥150%

UV resistance: Enhanced with 2-3% carbon black

PE (Polyethylene): For applications requiring superior moisture resistance, with:

Shore hardness: 60±5

Tensile strength: ≥20MPa

Elongation at break: ≥600%

Chemical Resistance: Superior to PVC in many environments

Thickness: 2.0mm for both PVC and PE sheaths, ensuring adequate protection while maintaining flexibility.

Color Coding: Typically black with longitudinal color stripes for phase identification (brown, black, gray for three phases).

Application: Extruded over the steel armor in a continuous process, forming a tight bond that prevents moisture ingress.

Voltage Ratings and Withstand Capabilities:

Rated voltage (U0/U): 12kV/20kV (phase-to-ground/phase-to-phase)

Power frequency withstand voltage (dry): 45kV for 60 minutes

Power frequency withstand voltage (wet): 35kV for 10 minutes

Lightning impulse withstand voltage (1.2/50μs): 125kV (positive and negative polarity)

Switching impulse withstand voltage (250/2500μs): 85kV

Current-Carrying Capacity (Ampacity):

Copper Conductors:

In air (30°C ambient): 450A

In ground (20°C ambient, 0.8 thermal resistivity): 400A

In duct (30°C ambient, 3 cables): 380A

Aluminum Conductors:

In air (30°C ambient): 420A

In ground (20°C ambient, 0.8 thermal resistivity): 370A

In duct (30°C ambient, 3 cables): 350A

Derating Factors:

40°C ambient: 0.91

50°C ambient: 0.82

60°C ambient: 0.71

Resistance and Loss Characteristics:

Copper Conductors:

DC resistance at 20°C: 0.074Ω/km per conductor

AC resistance at 50Hz: 0.085Ω/km per conductor

Aluminum Conductors:

DC resistance at 20°C: 0.124Ω/km per conductor

AC resistance at 50Hz: 0.135Ω/km per conductor

Reactance: 0.12Ω/km at 50Hz

Total losses at full load:

Copper: 162W/m (total for 3 conductors)

Aluminum: 182W/m (total for 3 conductors)

Partial Discharge Performance:

Partial discharge level:<10pC at 1.73U0 (20.76kV)

No measurable partial discharge at rated voltage (12kV phase-to-ground)

Tensile Strength:

Maximum pulling tension during installation: 15kN

Breaking load of complete cable: 20kN

Steel armor contribution to tensile strength: 70% of total

Flexibility and Bending:

Minimum bending radius during installation:

Copper conductors: 12 times cable outer diameter (≈300mm)

Aluminum conductors: 15 times cable outer diameter (≈375mm)

Minimum bending radius during operation:

Copper conductors: 18 times cable outer diameter (≈450mm)

Aluminum conductors: 20 times cable outer diameter (≈500mm)

Bending test performance: Withstands 10 cycles of bending to installation radius without damage to insulation or sheath

Impact Resistance:

Resists impact from 5kg weight dropped from 1m height (IEC 60811-503)

No penetration of armor or damage to internal components

Suitable for installation in areas with potential for mechanical contact

Crush Resistance:

Withstands a crushing force of 4kN/m without damage to electrical performance

Steel armor prevents conductor deformation under pressure

Temperature Range:

Continuous operating temperature: -40°C to +90°C

Short-term overload temperature: +130°C for up to 5 hours

Emergency overload temperature: +250°C for 5 seconds (short-circuit)

Temperature cycling: Withstands 1000 cycles between -40°C and +90°C without degradation

Water and Moisture Resistance:

Water absorption:<0.1% by weight after 24 hours immersion

Insulation resistance: >1000MΩ·km after 1000 hours immersion in water at 70°C

Water penetration: No water ingress after 24 hours under 10m head pressure

Chemical Resistance:

Resistant to:

5% sulfuric acid and hydrochloric acid (1000 hours exposure)

10% sodium hydroxide and ammonia solutions (1000 hours exposure)

Petroleum products, lubricating oils, and hydraulic fluids

Common soil contaminants and industrial chemicals

Suitable for installation in industrial zones, chemical plants, and coastal areas

UV and Ozone Resistance:

UV resistance: Retains >80% of mechanical properties after 2000 hours of UVB-313 exposure

Ozone resistance: Unaffected by ozone concentrations up to 200ppm (IEC 60811-404)

Suitable for outdoor installation without additional protection

Service Life Expectancy:

30+ years in normal operating conditions

20+ years in severe environments (industrial, coastal, high temperature)

Supported by accelerated aging tests showing<20% property loss after 10,000 hours at 135°C