What is Proximity effect in transmission line

What is Proximity effect in transmission line
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What is Proximity effect in transmission line ? Proximity effect refers to the redistribution of electric current in nearby parallel conductors carrying alternating current due to magnetic effects. Also find How to Reduce Proximity effect bellow.

These phenomena are important considerations in the design and operation of electrical transmission systems and can lead to increased resistance and power losses. Understanding the skin effect and proximity effect is crucial in electrical engineering as they impact the efficient transmission of energy. .

What is Proximity effect in transmission line :

One significant phenomenon that impacts efficiency is the proximity effect. Let’s break down this effect in simple steps:

1. The Magnetic Dance

What is Proximity effect in transmission line
  • Imagine two conductors in a transmission line carrying alternating current (AC). These currents create time-varying magnetic fields around each conductor.

2. Eddy Currents Join the Party

What is Proximity effect in transmission line
  • The changing magnetic fields from one conductor induce eddy currents within the other conductor. These eddy currents flow in a loop within the conductor, opposite the main current.

3. Current Redistribution

  • The interaction between the primary current and eddy currents leads to a non-uniform distribution of the main current within the conductor’s cross-section. This means the current gets “pushed” to one side of the conductor.

4. Consequences of the Shuffle

  • This uneven current distribution increases the conductor’s effective resistance, leading to Increased power loss: More energy dissipates as heat due to the higher resistance.
  • Voltage drop: Energy loss reduces the voltage delivered at the receiving end.

5. Factors Affecting the Hustle

The severity of the proximity effect depends on various factors, including 

  • Frequency: Higher frequencies induce stronger eddy currents, amplifying the effect.
  • Spacing: A larger distance between conductors weakens the interaction and reduces the effect.
  • Conductor size: Smaller conductors are more susceptible to current crowding due to limited cross-section.
What is Proximity effect in transmission line

Disadvantages of Proximity effect in Power system

Understanding the proximity effect is crucial for electrical engineers to design efficient transmission lines. We can mitigate this effect and minimize power losses by employing strategies like increasing conductor spacing, reducing frequency, or using thicker conductors.

  • Increased power loss: The uneven current distribution in the conductors caused by the proximity effect increases the resistance of the line, which leads to more power being lost as heat. This can be a significant problem for long transmission lines, as it can reduce the efficiency of the system and increase the cost of transmitting power
  • Voltage drop: The power loss caused by the proximity effect also results in a voltage drop along the transmission line. This can lead to problems for equipment at the receiving end of the line, as it may not receive the voltage that it is designed for.
  • Skin effect: At high frequencies, the proximity effect can cause the current to flow mainly on the outer surface of the conductor. This is known as the skin effect, and it can further increase the resistance of the line and lead to even more power loss.
  • Increased electromagnetic interference (EMI): The eddy currents created by the proximity effect can generate electromagnetic interference, which can interfere with the operation of nearby electronic equipment.

How to Reduce Proximity effect

Understanding how to mitigate the proximity effect becomes paramount in optimizing the performance of electrical systems. Here are some strategies to minimize its impact:

1. Reducing Conductor Size

One effective approach is reducing the size of the conductor. By doing so, the magnetic flux and, consequently, the proximity effect are mitigated.

2. Increasing Conductor Separation

Another method involves increasing the distance between two conductors. In cable manufacturing, engineers use dummies to achieve this separation and curtail the proximity effect.

3. Playing with Frequency and Voltage

While it is practically impossible to alter AC frequency, increasing the voltage can be a game-changer. By stepping up the voltage, engineers can mitigate the proximity effect, ensuring optimal performance in electrical systems.

Difference Between Skin Effect And Proximity Effect

Skin effect refers to the tendency of alternating high-frequency currents to crowd toward the surface of a conducting material, increasing the resistance of the conductor.

On the other hand, proximity effect is the redistribution of electric current occurring in nearby parallel electrical conductors carrying alternating current, caused by magnetic effects. Both effects are influenced by factors such as the diameter and shape of the wire, as well as the frequency of the current.

The skin effect increases with the increase of cross-section, permeability, and supply frequency while it reduces with the increase in resistivity of the conductor material. Meanwhile, the proximity effect is caused by the current of the other nearby conductor, leading to alternating flux in a conductor.


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