How to compute for the losses in transmission lines?

Losses in the transmission lines can be determined less complicated compared to transformers and distribution systems. The basic computation of it usually surrounds to the fundamentals of ohm's law. Due to the simplicity of the transmission line configuration, solving for its line losses requires no advance knowledge in any electrical principles. However, there are also portion of these line losses that better understanding is necessary. 

Total transmission line losses can be broken down into three relevant parts namely; conductor losses, dielectric heating & radiation losses, and coupling & corona losses. 

Conductor Losses: 

Conductor losses is also popularly known as line heating losses since electric current that passes through a conductor releases heat. It is known that any metallic materials possesses inherent resistive nature that is why it is inevitable that during electrical flow through these materials unavoidable power loss occurs.Typical transmission line conductors consist of resistance that is uniformly distributed throughout the system,as a result it is safe to say that the total power loss in the line is directly proportional to the square of the current that passes and the total resistance of the wire. In addition to that, resistance of the wire is inversely proportional to the diameter of the conductor thus, the bigger the wire diameter, the lower resistance it can give. 

In relation to conductor losses,beside the conductor type,length & diameter as factor for its line resistance, another contributing phenomenon is the Skin effect. In an AC system, the flow of current in the cross section of the wire is not uniformly distributed. Skin effect tends to make the current flow concentrated more in the outer layer of the conductor. Since a very small area of the wire carries that current, line resistance increases at the same time increases the dissipated power. 


Line loss formula for 3-phase transmission line


2. Dielectric Heating Losses and Radiation Losses

3. Coupling Losses and Corona:

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