What are the Types of Overhead Transmission Lines?

Overhead transmission or overhead line is used to transmit electric power from one place to another place with the help of a conductor which is called a transmission line. However, the transmission line is an essential part of the electrical power system. There are two types of electricity transmission systems: overhead transmission and underground transmission systems. Both are used to transmit high power from one place to another place. We will broadly discuss here what are the types of overhead transmission lines so get in touch with us.

What are the Types of Overhead Transmission Lines?

The electrical power system consists of a large number of components power transformer, electrical circuit breaker, current transformer, potential transformer, transmission equipment, and others. In this section, we will discuss the overhead transmission system. We have said that there are two types of overhead transmission lines, such as overhead and underground transmission systems. However, the overhead transmission lines can be divided into three main types based on transmission voltage and distance:

  • Short-range overhead transmission line.
  • Medium range overhead transmission line.
  • Long-range overhead transmission line.

1. Short Range Overhead Transmission line

The area of a short transmission line is no longer than the medium and long transmission lines. Those transmission line lengths are 50 kilometers and line voltage is up to 20KV such an overhead transmission line is called a short transmission line.

There are some conveniences of a short transmission line. A short transmission line has no corona effect and the capacitance effect is also less. It is because a short-length overhead transmission line is out of such danger, and these effects are neglected here. It is noted that though the capacitance effect is not considered here inductance and resistance are considered.  

2. Medium Range Overhead Transmission Line

The length of the medium transmission line is comparatively higher than the short transmission line. However, if the line voltage becomes more than 20KV to 100KV and the transmission line length becomes 50 to 100 kilometers such an overhead transmission line is called a medium overhead transmission line.

This medium transmission line has some effects like capacitance, resistance, and inductance but the capacitance effect is taken into account. There is some other problem such as corona because the medium transmission line carries comparatively high voltage. For this reason, the Corona effect will also be considered.

3. Long Range Overhead Transmission Line

The long transmission line is another crucial part of the high-voltage power transmission system. Long transmission means that it has something special. Yes, it has something special. A long overhead transmission line means there is no voltage limit and distance.

However, it has been estimated that the long transmission line voltage limit is more than 100KV and the distance is more than 100 kilometers such type of overhead transmission line is called a long transmission line. Due to the high transmission voltage and greater distance, the corona and skin effect will be considered and the capacitance effect will also be considered. It is noted that high voltage transmission is more beneficial.    

33 KV Overhead Transmission Lines

There are two types of transmission lines based on transmission voltage, such as primary transmission line and secondary transmission line. The primary transmission line starts running from the generating station and carries very high voltage (132KV, 220KV, and more). These high-voltage overhead lines meet at a substation which is called a primary substation or sometimes called a national grid overhead lines substation. From this primary substation, voltage is stepped down to 66KV, or 33KV by the step-down power transformer.

These 33KV overhead lines rush to several substations which is called secondary substations and this type of overhead line (33KV overhead line) is called a secondary overhead transmission line. Therefore, this 33KV overhead transmission line runs for the different types of primary distribution substations and steps down the voltage (33KV/11KV) to 11KV by using a step-down distribution transformer. The several 11KV primary distribution lines run to another distribution substation which is called the secondary distribution substation and step down the voltage (11KV/400V) to 400 volts.  

Now, if you have a three-phase load then you need a three-phase line, and if you have a single-phase load then you need a single-phase and neutral wire. It is noted that a three-phase load requires only three phases but no neutral is required. If you take a single-phase load, you must require a neutral connection.

What is Overhead Transmission Line Efficiency?

The ability to transfer sufficient power from the sending end to the receiving end and obtain the same power at the receiving end is called transmission line efficiency. Efficiency is a crucial part of every machinery. Efficiency is most important for all sectors. The most efficient machine is the electrical power transformer approximately 95% or more due to low losses. Efficiency becomes low due to losses. The efficiency of a transmission line depends on the line voltage, transmission distance, conductor, and other factors. It is noted that efficiency becomes low due to losses. 

Final Word

The electrical power system is one of the big discussions. It is impossible to explain everything by writing but we can get basic things from here. However, the transmission line is a major part of the electrical power system. Basically, the transmission line begins from the generating station and is divided with different voltages in the various types of substations. However, we have discussed here the types of overhead transmission lines. We hope it may give a clear basic concept about overhead high voltage and low voltage transmission lines. So stay with an open read to clear your concept.  

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