NB/T 42060

Standard Overview  

NB/T 420602015 is a Chinese energy industry standard issued by the National Energy Administration (NEA) for Thermal Resistant Aluminum Alloy Conductors, Steel Core Reinforced for Overhead Transmission Lines. It specifies requirements for high temperature resistant conductors with galvanized steel or aluminum clad steel cores, primarily used in high voltage power transmission networks rather than general construction or telecommunications .  

Key Technical Requirements  

• Material Composition:  
  • Thermal Resistant Aluminum Alloy: Two grades:  
  • NRLH1: Standard thermal resistant alloy (continuous operation up to 150°C).  
  • NRLH2: High strength thermal resistant alloy (continuous operation up to 150°C), both compliant with GB/T 305512014.  
• Steel Core:  
  • Galvanized Steel Wires: Five strength grades (G1A–G5A per GB/T 34282012).  
  • Aluminum Clad Steel Wires: Two types (LB14 and LB20A per GB/T 179372009).  
  • Optional Coatings: Zinc5% aluminum rare earth or 55% aluminum zinc alloy for enhanced corrosion resistance.  
• Structural Design:  
  • Conductor Types: Includes steel reinforced thermal resistant aluminum alloy strands (ACSR/TW) and aluminum clad steel reinforced variants.  
  • Core Configurations: Layered concentric stranding around a steel core for mechanical stability.  
• Performance Metrics:  
  • Electrical Conductivity: Aluminum alloy ≥58% IACS (NRLH1) or ≥53% IACS (NRLH2).  
  • Mechanical Strength: Steel core tensile strength up to 1,830 MPa (G5A grade).  

Application  

These conductors are engineered for high temperature overhead power transmission:  

• High Capacity Power Lines: Enables increased ampacity (up to 150°C) without sagging risks, ideal for grid upgrades .  
• UltraHigh Voltage (UHV) Networks: Critical for China’s national UHV projects (≤1,000 kV) .  
• Corrosive/Harsh Environments: Coastal, industrial, or highpollution areas where enhanced corrosion resistance is essential .  

Related Standards  

•  GB/T 30551: Specifications for thermal resistant aluminum alloy wires.  
•  GB/T 3428: Chinese standard for galvanized steel cores.  
•  IEC 61089: International equivalent for round wire concentric lay conductors.  
•  ASTM B398: Comparable ASTM standard for aluminum clad steel wires.