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Need to know proximity effect in transmission line

Issuing time:2022-07-02 12:38


Alternating flux develops within the adjacent conductors that carry alternating current. This causes the circulating current to flow within the conductor, creating a current distribution within the transmission lines. However, the distribution is usually non-uniform in nature.

All these factors increase the apparent resistance of the conductor. Now, this directly affects the conductors’ apparent resistance. The voltage drops, and power is lost along the transmission lines as the resistance increases. This entire phenomenon is known as the proximity effect. And these effects are easily detectable among the tower accessories after their installation.

So, what would be the outcome of the proximity effect on the transmission lines? Let’s find out.

Proximity effect and its impact on transmission lines

When a conductor is carrying current in the same direction, the current has a possibility to concentrate at the conductor’s edge. But, if the current flows through the opposite direction, within adjacent conductors, then the current concentrates on the nearest side. This can be seen in both the conductors. Further, this factor makes the proximity effect even more intense within the tower accessories.

For example, if you have a conductor carrying 50-hertz of current, it will be less affected by the proximity effect. But, if you take another conductor with a 60-hertz current capacity, the rate will be more. Usually, the conductors that are greater than 125 mm2, the proximity effect, are remarkably essential.

However, you won’t be able to see the proximity effect in DC transmission. And the core reason is that DC transmissions have zero frequency and varying magnetic fields.

Factors influencing the proximity effect

As already mentioned, the windings are quite close in the case of AC transformers and inductors. The proximity effect is predominant in this type of transmission. Additionally, the proximity effect also affects the nearby conductors.

The factors that influence this effect are –

The material of the Conductors

The more ferromagnetic material, the more proximity effect it will experience.


The proximity effect tends to become more intense with the increase in frequency.

The structure of the conductor

Two types of conductors are used – Solid and Stranded conductors. But, still, the proximity effect is much higher in the case of a solid conductor. Because Standard conductors have a low surface area, reducing the proximity effect.

However, internal and external proximity effects exist in Stranded conductors’ cases. And, you can detect the effect primarily in ACSR (Aluminum Core Steel Reinforced) conductors.

The diameter of the conductor

The proximity effect has a direct link with the diameter of the conductor. As the conductors’ diameter increases, the proximity effect also increases. So, if the current flowing through the system is increased, it makes the proximity effect much stronger.

Is there a possibility of reducing the proximity effect?

After you understand the reasons for creating or enhancing the proximity effect, you can easily reduce the influence.

Reduce the surface area of the conductor

You can replace the Solid conductors with Stranded conductors to decrease the surface area. And, this will indirectly work to reduce the proximity effect within the tower accessories.

Increase the voltage

If you constantly transfer the power through the transmission line, it will decrease the current and increase the voltage. Further, this reduces the conductors’ size and reduces the proximity effect.

Enhance the space between the conductors

Have you ever thought of using dummy conductors? This has the potential to increase the space between two conductors and reduce the proximity effect. Furthermore, it can also work as a supporting structure for the transmission lines.


You cannot find the proximity effect in the case of low voltage systems and DC circuits. It only creates a limitation within the AC circuits. But, if you want perfect microstrips for circuit boards with a low proximity effect, then Hanford Electric have the ideal solution.

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