ASTM B857-22 PDF

Overview

ASTM B857-22 is the Standard Specification for Shaped Wire Compact Concentric-Lay-Stranded Aluminum Conductors, Coated-Steel Supported (ACSS/TW). Published by ASTM International, this standard specifies requirements for ACSS/TW conductors used in overhead electrical transmission and distribution. ACSS/TW conductors are constructed using trapezoidal-shaped aluminum wires compactly stranded around a steel core, enhancing their efficiency for use as overhead conductors, especially where high strength and conductivity are essential.

The standard defines criteria concerning conductor construction, material properties, mechanical and electrical performance, and test methods. It contributes to reliability, consistency, and compatibility in specifying, manufacturing, and deploying ACSS/TW conductors worldwide.

Key Topics

• Conductor Construction:

  • Defines requirements for compact concentric-lay-stranded aluminum conductors using trapezoidal wire (TW) design.
  • Specifies a central core of round, coated steel wires, surrounded by two or more layers of aluminum wires.
  • Permits various classes and coatings of steel core wires, such as galvanized, aluminum-clad, or Zn-5% Al-MM alloy coated.

• Material Properties:

  • Aluminum wires must meet the requirements for O Temper in accordance with relevant ASTM standards.
  • Steel core wires must comply with applicable ASTM specifications for strength and coating.
  • Electrical resistivity, mechanical strength, and density values are identified to ensure standardized performance.

• Performance Criteria:

  • Rated conductor strength is determined by mechanical and electrical tests.
  • Mass and diameter tolerances are specified for finished conductors.
  • Requirements for welds and joints in aluminum wires are detailed to promote reliability.

• Testing and Quality Assurance:

  • Outlines test procedures for electrical resistivity, tensile strength, elongation, and overall conductor dimensions.
  • Provides criteria for inspection, packaging, and marking to ensure traceability and quality control.

Applications

ACSS/TW conductors standardized by ASTM B857-22 are primarily used in:

• High-voltage Overhead Transmission Lines: Their strength and compact design make them suitable for long spans, heavy loads, and challenging installations.
• Power Distribution Systems: Enhanced aluminum area for a given diameter improves current-carrying capabilities, supporting network efficiency.
• Upgrades of Existing Infrastructure: ACSS/TW enables capacity increases without major changes to tower or pole structures, leveraging backward compatibility with standard conductor types such as ACSR and ACSS.
• Extreme Environmental Conditions: The robust steel core and suitable coatings confer durability under high tensions, elevated temperatures, and adverse weather.

Related Standards

ASTM B857-22 references and aligns with several key standards for consistent performance and compatibility in the field of electrical conductors, including:

• ASTM B232/B232M: Concentric-Lay-Stranded Aluminum Conductors, Coated-Steel Reinforced (ACSR)
• ASTM B609/B609M: Aluminum 1350 Round Wire for Electrical Purposes
• ASTM B498/B498M: Zinc-Coated Steel Core Wire for Use in Overhead Conductors
• ASTM B500/B500M: Stranded Steel Core for Overhead Electrical Conductors
• ASTM B549, B606, B802, B803, B857, B958: Additional specifications for various core wire coatings and strengths
• ASTM B354: Terminology Relating to Uninsulated Metallic Electrical Conductors

These standards, together with ASTM B857-22, form a comprehensive foundation for specifying, manufacturing, and installing reliable, high-performance ACSS/TW aluminum conductors.

Keywords: aluminum conductors, shaped wire, concentric-lay stranded, steel supported, ACSS/TW, overhead electrical conductors, ASTM B857-22, power transmission, compact aluminum conductor, ACSS, ACSR.