Types of Aluminum Conductors

• All Aluminum Conductors (AAC)

• All Aluminum Alloy Conductors (AAAC)

• Aluminum Conductor Steel Reinforced (ACSR)/Composite Stranded Conductor

• Aluminum Conductor Alloy Reinforced (ACAR)

• Aluminum Conductor Composite Core (ACCC)

 Types of Al Conductors
AAC

AAC with insulation

ACCC

AAAC

ACSR
 Conductor Layer, Strand and Diameter
2nd layer 1st layer

Total no. Total no. of Diameter of conductor, Cross sectional view of

of layers, strands, 𝑵 = 𝑫 = 𝟐𝒙 − 𝟏 𝒅 conductor
𝒙 𝟑𝒙𝟐 − 𝟑𝒙 + 𝟏

2 7 (1+6) 3d
Alternate layer of strands
spiraled in opposite
3 19 (1+6+12) 5d directions

4 37 (1+6+12+18) 7d

Alternate layer of strands are laid in spiraled form

in opposite directions to hold the strands together
and make the outer radius of one layer coincide
with the inner radius of the next.
 All Aluminium Conductor (AAC)/ Aluminium Stranded Conductor
[Advantages + Disadvantages] of Al conductor on slide 7 and stranded conductor on slide 4 (In part 1 lecture). Also

Advantages Disadvantages Applications

Have a high degree of corrosion Less tensile strength i.e. In urban areas for power distribution where
resistance; for this reason they are used more sag the spacing is short and the supports are
extensively in coastal areas closer together

To increase the tensile strength, AAAC can be used

AAC
Sag
Sag

Tensile strength
Less tensile More tensile
strength more sag strength less sag
 All Aluminum Alloy Conductors (AAAC)

This is an alloy of aluminium known as Silmalec which contains 0.5% of silicon, 0.5% of magnesium and rest of
aluminium. This makes an improvement in tensile strength than AAC

[Advantages + Disadvantages] of Al conductor on slide 7 and stranded conductor on slide 4. Also

Advantages Applications
• More tensile strength than AAC i.e. less sag than AAC In hilly areas, railway areas, ice areas.
• Length of span (distance between two towers/supports) increased

Tensile strength can be further increased more by reducing the length of span. How to reduce
length of span. Use more tower??? Suppose, number of tower is 2 for 500 m span length. Now it
can be 3 for same 500 m. However, addition of tower increases the cost. Therefore ACSR is AAAC
used.
250m 250m
500m
 Aluminum Conductor Steel Reinforced (ACSR)

ACSR has a central steel core of few strands and Steel strands (2 layers); No. of strands: 7(1+6)
surrounded by aluminum conductors in one or
more strands

Aluminum strands (2 layers); Total no. strands:30 (12+18)

7
 Advantages and Applications of ACSR

Advantages Applications
 The steel core provides the more tensile strength Used in high voltage
transmission lines for
 Surrounded aluminum conductors carry the current long distances

 ACSR satisfies the requirement of a good transmission line, i.e. it

good conductivity and sufficient strength than AAC and AAAC

 More tensile strength in ACSR results in less sagging so greater

span length between towers
 Since steel carries no current, diameter of ACSR is increased
comparing other conductor for the same amount of current flow.
This reduces the corona loss.
ACSR Types/Ratio of Aluminum and Steel in ACSR [Al+St]
 ACSR Conductor Specifications

Serial of Operating Current No of Strands Overall Unit Weight

ACSR Voltage (kV) carrying Diameter (kg/meter)
Conductor capacity at (cm)
75°C (Amp) Aluminium Steel

1 33/66 300 6 7 1.42 0.394

2 66/132 480 30 7 2.10 0.976
3 220 735 54 7 2.86 1.62
4 220/400 800 54 7 3.18 2.02

1 (Dog) 2 (Panther) 3 (Zebra) 4 (Moose)

Increase more conductivity and tensile strength and
Reduce corona effect

Expanded ACSR

ACCC

Bundled Conductors
 Expanded ACSR
Expanded ACSR conductors are made by adding plastic or paper between the inner steel strands from the outer aluminum
strands. The paper gives a larger diameter (and hence, lower corona) for a given conductivity and tensile strength.
Expanded ACSR is used for some extra-high-voltage (EHV) lines.

Some voltage classifications are as follows:

• HV: 115 kV, 138 kV, 230 kV
• EHV: 345 kV, 500 kV, 765 kV
• UHV: 1000 kV, 1500 kV
 Aluminum Conductor Composite Core (ACCC)

• 28% more aluminum for increased conductivity than other conductors

• Core incorporates high-strength carbon and glass fibers with special polymers.

Advantages Disadvantages Applications

• Composite core is lighter and stronger than steel ACCC costs 2.5–3 Can replace ACSR
• Higher conductivity times as much as without modifying
• Reduced line loss ACSR structures due to it’s
• Reduced sag and high-strength core allows greater spans (reduces similar weight and
number of structures and reduces height requirements) tension properties
 Bundled
Conductors
 Bundled Conductors (Increased no. of conductors per phase)
• More than one conductor per phase (Two, three, four or more). For transmission of power beyond 200kV bundled conductors are
preferred.

One conductor/phase More than one conductor/phase

 Bundle arrangement
The conductors of a bundle are separated at constant intervals with spacer dampers to connect the conductors in parallel.
They also prevent clashing of the conductors and prevent them from swing in the wind.

2- bundled conductor

Spacer
 Advantages of Bundled Conductors

 Reduce line inductance which in turn increases power transfer capability of line.

 Reduce corona discharge. Using several conductors nearby instead of one conductor, forming a bundled conductor
with larger diameter which leads to a reduction of voltage gradient and hence the possibility of corona formation.

 Reduction in the formation of corona discharge leads to less power loss and hence improved transmission efficiency of
the line.

 Reduction in communication line interference due to reduction in corona.