Concentric-Lay-Stranded Aluminum Conductors, Composite Reinforced (ACCR)

B978/B978M- 14: Standard Specification for Concentric-Lay-Stranded Aluminum Conductors, Composite Reinforced (ACCR)

In the demanding world of electrical power transmission, the integrity and performance of overhead conductors are paramount. ASTM International's B978/B978M- 14: Standard Specification for Concentric-Lay-Stranded Aluminum Conductors, Composite Reinforced (ACCR) provides an essential framework for ensuring the quality and reliability of these critical components. This comprehensive standard is an industry-leading document for engineers and designers specifying advanced conductor solutions.

What is B978/B978M- 14?

ASTM B978/B978M- 14 is an authoritative standard developed by ASTM Committee B01 on Electrical Conductors. It meticulously defines the requirements for concentric-lay-stranded conductors constructed with round aluminum-zirconium alloy wires and a composite core. The primary purpose of this specification is to ensure that ACCR conductors meet stringent performance criteria for overhead electrical applications, offering superior strength and thermal performance compared to traditional conductors.

Scope & Purpose

This specification governs the design, material composition, and construction of ACCR, specifically addressing conductors made from aluminum-zirconium alloy wires and an aluminum matrix composite (AMC) core. It details requirements for the individual wires, the stranding process, lay lengths, and the calculation of rated conductor strength. The standard does not cover the installation or field testing of these conductors, focusing strictly on the material and manufacturing specifications to ensure product conformity.

Who Must Comply?

• • Primary audience: Materials Engineers, Electrical Engineers, Project Engineers, Design Engineers, and Quality Control Inspectors involved in the specification, design, manufacturing, and procurement of overhead electrical conductors.
• • Industries affected: Electrical Power Transmission and Distribution, Utilities, and Telecommunications industries.
• • Compliance nature: Compliance is typically voluntary, driven by contract specifications, project requirements, and a desire to utilize proven materials that meet high industry standards.
• • Enforcement: Compliance is generally ensured through contractual agreements, third-party inspections, and adherence to material certifications during procurement and project execution.

Key Requirements Overview

The standard requires that both the aluminum-zirconium alloy wires and the AMC core wires meet specific material property requirements before being incorporated into the conductor. Professionals must ensure that the stranding process adheres to defined lay lengths and directions to achieve the specified conductor geometry and performance. Key provisions include detailed methods for calculating the rated strength of the completed conductor, which is crucial for load-bearing applications. Furthermore, the specification outlines requirements for joints in the aluminum-zirconium alloy wires, while strictly prohibiting joints in the AMC core wires.

Related Standards & References

This specification works in conjunction with several other ASTM standards. ASTM B941 provides the detailed requirements for the aluminum-zirconium alloy wire, while ASTM B976 specifies the criteria for the aluminum matrix composite core wire. ASTM B263 is also referenced for the determination of the cross-sectional area of stranded conductors, a fundamental parameter for electrical design. These complementary standards ensure a holistic approach to the quality assurance of ACCR systems.