Electrical

# Which conductor is used in the transmission power line and which conductor is best for power transmission?

The major element in the power transmission is the electrical conductor and it does the transmission of power from the generating station to the consumers. So the conductor will carry electrical power from the generating power plants to electrical substations and from there it is distributed and thus providing power to the consumers so without the conductors we won’t be able to do the power transmission. So we must select the material for the conductor very carefully and it must have a long life and should be economical too.

#### Why stranded conductors are used in the transmission line?

In case we use larger conductors then we won’t be able to handle it easily and it would be damaged if it bends and because of this stranded conductors are used for power transmission. A stranded conductor is a conductor in which a group of wire is twisted to form a single conductor and this would make the conductor more flexible and that’s why stranded conductors are used in the transmission lines.

Advantages of stranded conductors

• Current will be increased
• It has low reactance than a single conductor
• It can also reduce the corona loss at high voltages
• It will also reduce the voltage gradient

#### How to select transmission line conductors?

• The diameter of the conductor
• It must be selected according to the conductivity of the conductor
• Material cost
• Weight must be considered
• The ability of the material to resist vibrations
• It must be selected according to the breaking strength of the conductor
• It must be selected according to the thermal expansion
• It must have less resistance
• It must have less expansion coefficient and the corona loss must be very less
• It should have high tensile strength so that it can withstand mechanical stress
• It should have physical stability so that it can withstand environmental conditions

#### Why power transmission is done in AC and why transmission is done in three-phase?

The major advantage of using AC power is that it can be steeped up to any voltage level from the generating stations and because of the high voltage the current will be reduced. So when the current reduces the conductor size can be reduced and it would save a lot of money. AC power is used because there won’t be any voltage drop and because of this long-distance transmission is possible. Three-phase is used for power transmission because in three-phase transmission it won’t use more conductor material like in two-phase for a specified power.

#### Which conductor is used in the transmission power line? What are the different types of overhead conductors?

Copper and aluminum are widely used as transmission line conductors but the copper conductors are replaced by aluminum. The conductivity of silver is higher than copper but because of its cost, it is not possible to use silver for transmission purposes. Aluminum wires have better conductivity than copper according to the weight.

In early days copper wires were used for power transmission but now it is replaced by aluminum wires and the major reason for that is the cost of the copper wire. The other reason for using aluminum is that the weight of the copper is very high compared to an aluminum conductor of the same length and because of this it is a little bit difficult to use copper as overhead lines. Copper is a good conductor than aluminum it has very little resistance when compared to aluminum but while using the copper for transmission purposes we must use more number of poles because the weight of the copper and because of this it is not economical. Mostly for house wiring we don’t use aluminum and it is because the resistivity of the aluminum is high and because of this we need to increase the size of the conductor and that’s why copper is used for house wiring. The copper wire is fireproof and is flexible than an aluminum conductor.

Types of conductors

All aluminum conductors

This type of conductor is mostly used for cities and in places where spacing is less and this material has high purity.

Aluminum conductors steel reinforced

These conductors have a steel core that has strands of aluminum surrounding it and these conductors are used for long-range of transmission. This type of conductor has greater tensile strength.

All aluminum alloy conductors

This conductor is constructed from aluminum-magnesium-silicon alloy and its conductivity is very high.

#### What is bundled, conductors?

A bundled conductor has three or four conductors for each phase and they are separated. These conductors are used for high voltage transmission because during high voltage transmissions normal conductors have corona and noise, this would affect the power transmission.

### Ashlin

post-graduate in Electronics & communication.