Bare Overhead Conductors (AAAC, AAC, ACSR, ACSR-II)

AAAC
Bare all aluminum alloy conductors (AAAC) are concentric-lay-stranded consisting of aluminum alloy 6201 wires wrapped helically around a central wire. The aluminum is heat-treated to a T81 temper to provide superior strength.

Features and Benefits
AAAC conductors provide a higher strength to weight ratio than traditional AAC conductors, and better corrosion resistance than ACSR conductors.

Applications
Stranded bare AAAC may be used for overhead line installations where the higher strength or temperature ratings of ACSR, ACCR or other types of conductors is not required, but improved sag performance to AAC is desired.
 

AAC
Bare all aluminum conductors (AAC) are concentric-lay-stranded consisting of one or more layers of aluminum alloy 1350 wires wrapped helically around a central wire. Each successive layer has six wires more than the underlying one. Increasing the number of wires for any given cross-sectional area provides greater flexibility. The most commonly used strandings consist of 7, 19, 37, 61 and 91 wires.

Class AA strandings are used for bare overhead lines. The direction of lay for the outer layer is right-hand and is usually reversed in successive layers. The temper of the wires is full hard-drawn (H19).

Features and Benefits
AAC conductors are the most economical since their lighter weight means lower unit length costs, easier handling during installation and the use of simpler fittings. They are inherently corrosion resistant due to their homogeneous construction.

Applications
Stranded bare AAC conductors may be used in overhead line installations where the design parameters do not require the higher tensile strength or temperature ratings provided by ACSR, ACCR or other types of conductors

ACSR
ACSR is a composite concentric-lay stranded conductor consisting of a central steel core around which are stranded one or more layers of aluminum alloy 1350-H19 wires. The steel core may consist of a single wire, 7, 19, 37 or more concentrically stranded wires. They are normally protected against corrosion by a zinc coating. The standard Class A coating is usually adequate for ordinary environments. Heavier Class B or Class C coatings may be specified for greater protection. A special high-strength steel core with a Class A coating is also available.

Features and Benefits
ACSR conductors have a long service record due to their economy, dependability and favourable strength to weight ratio. Such conductors combine the light weight and high conductivity of the aluminum wires with the tensile strength and ruggedness of the steel core. For overhead line design, this enables higher tensions to be used with less conductor sag and longer spans than would be possible with most other types of conductors.

Applications
Aluminum conductors, steel reinforced (ACSR) are widely used for overhead transmission and distribution lines.

ACSR-II

ACSR-II Overhead Conductors are manufactured from two standard ACSR conductors which are twisted together with a very long lay (8-10 feet). This simple cable design is very effective in reducing ice loading and wind-induced conductor motion, and the costly damage that these can cause.

AAC (all aluminum conductor) and AAAC (all aluminum alloy conductor) are also available in the twisted configuration, and are identified as AAC-II and AAAC-II respectively.

Features and Benefits
The unique physical properties of ACSR-II conductors can result in real savings in the cost of a T&D system.

Fatigue damage to conductor strands is reduced, thus enhancing life-expectancy and delaying replacement.

Accessories (ie, vibration dampers, armor rods, and anti-galloping devices) normally used with standard conductors to reduce conductor motion can be eliminated.

The higher installation tension permitted with ACSR-II conductor results in reduced structure costs through fewer and smaller structures.

Lower operating temperature and resistance is obtained.

Higher load capacity is achieved.

Applications
Aluminum conductors, steel reinforced (ACSR) are widely used for overhead transmission and distribution lines. ACSR-II is a superior construction of this cable type suited to applications where wind-induced conductor motion and ice loading are risk factors for potential costly cable damage. The twisted ACSR-II cable reduces the impact of aeolian vibration, conductor galloping and sub-conductor oscillation.

Compared to standard ACSR conductor of equivalent cross-sectional area, ACSR-II conductor has a larger surface area allowing for greater heat dissipation. This means that for a give current, ACSR-II conductor will operate at a lower temperature. Similarly, ACSR-II conductor has a greater ampacity than the equivalent single ACSR conductor.