Dec 12, 2013

Selection of Conductors



conductors

Economically, conductors signify between 20 to 40 percent of entire cost of the transmission line; accordingly their choice is of prime reputation. In past days of power transmission, copper was principally used because the materials of overhead lines conductor, but with the enlargement of electricity grids, many factors, like cost, weight, convenience and conduction, have just about compelled Overhead Line design Engineers to target aluminium element based mostly conductors.

Example:
AAC = All Aluminium Conductor
ACRS = All Aluminium Conductor Steel Reinforcement
AAAC = All Aluminium Alloy Conductor
The Steel conductors are still wide used as overhead line earth wires and conjointly as section conductors on countryside distribution lines.

Example:
SC/GZ = Galvanized Steel Conductor
SC/AC = Aluminum Clad Steel Conductor

Phase Conductors:

The conductor fulfills an electromechanical device function; therefore each the electrical and mechanical features are to be thought of.

Electrical constraints:

The most vital parameter moving the selection of conductor is its resistance, because it impacts voltage regulation, power loss and current grade. For AC lines, the perimeter of a conductor disturbs the inductance and therefore the capacitance. Upto a voltage of 132kV, the higher consideration are typically adequate, but at higher voltages, the higher than gradient on conductor surface could need the choice of a conductor on the premise of its diameter, so resulting in the utilization of bundled conductor.

Mechanical Constraints:

As previously directed, Aluminium based mostly conductors represent the very best percentage of conductor usage. The strategic mechanical material goods of aluminium alloy have conjointly been recognized for long term; however AAAC has continuously been dearer than ACSR, for equivalent conductivity. But there are cases wherever initial price isn't the governing factor. One in all these is that the corrosion performance, since being chemical element, the chance of bimetallic corrosion amongst the zinc and aluminium on the steel core are absent. Accordingly AAAC conductors are used on lines in coastline areas

Corrosion Performances:

The below table provides a sign of the comparative corrosion act of assorted conductor types. The recommendations ought to be changed by native expertise, for instance, for salt sprig pollution the virtual distances from the supply rely upon the predominant winds and terrain. Special circumstances like crop dusting which has been renowned to possess severe effects, ought to even be taken under consideration.
 

Suggestion of relative corrosion performances of conductor
















CONDUCTOR
SALT SPRAY POLLUTION
INDUSTRIAL POLLUTION
TYPE
OPEN OCEAN
BAYS INLETS
SALT LAKES
Acidic
Alkaline
AAC
1
1
1
3
AAC/6201
1
1
2
3
AAAC/1120
1
1
1
3
ACSR/GZ
3
2
2
3
ACSR/AZ
2
1
2
3
ACSR/AC
1
1
2
3
SC/GZ
3
2
3
2
SC/AC
1
1
2
3
HDCu
1
1
2
1

1 = Good performances
2 = Average performances
3 = Poor performances


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