ACSR conductors, which stands for Aluminum Conductor Steel Reinforced, have outer conductors made of aluminum.

ACSR conductors are commonly used in overhead power transmission lines due to their high strength and conductivity. They are composed of a central steel core surrounded by one or more layers of aluminum strands.

Key Points:
- ACSR conductors have outer conductors made of aluminum.
- The central core of ACSR conductors is made of steel.
- The combination of aluminum and steel provides the conductor with both strength and conductivity.

Explanation:
ACSR conductors are designed to have a high strength-to-weight ratio, making them suitable for long-distance power transmission. The steel core is responsible for providing the required strength, while the aluminum strands offer excellent conductivity.

The choice of aluminum for the outer conductors is crucial for several reasons. Firstly, aluminum is a lightweight material, which reduces the overall weight of the conductor. This is important for overhead power transmission lines, as lighter conductors put less strain on the supporting structures, such as poles or towers.

Secondly, aluminum has a high electrical conductivity, allowing for efficient transmission of electricity. The outer layer of aluminum strands ensures that the majority of the current flows through the conductor, minimizing losses.

Furthermore, aluminum is a cost-effective material compared to alternatives like copper. It is abundant, widely available, and less expensive, making it a preferred choice for power transmission applications.

In conclusion, ACSR conductors have outer conductors made of aluminum. The combination of aluminum for conductivity and steel for strength makes ACSR conductors an ideal choice for long-distance power transmission.