What is Proximity Effect & Its Factors

In superconductivity, the term proximity effect is used to explain the phenomenon that happens once a superconductor is arranged in contact with a standard non-superconductor. Generally, the critical temperature of the superconductor can be suppressed & weak superconductivity signs can be monitored above microscopic distances within the normal material. The proximity effect is first observed by R. Holm & W. Meissner through their pioneering work. They have monitoring zero resistance within pressed contacts of SNS because the two metals in these contacts are divided through a thin film of a normal metal. Sometimes, the supercurrent discovery within SNS contacts can be wrongly credited to Brian Josephson’s work in the year 1962. So this effect was recognized long before through his journal which is understood like proximity effect.

What is the Proximity Effect?

Definition: Once the conductor carries AC which is known as alternating current, and then there is a constantly changing flux that can be connected to the near conductor in surrounding area so that current density can be changed in both the conductors and eddy currents can also induce within the conductor in the surrounding area. This is known as the proximity effect.

Cause of Proximity Effect

To know how the proximity effect causes, here we have explained the following example. In the following figure, there are two conductors namely A & B which carry current in equal direction. Here ‘A’ is the magnetic field that can be generated through the ‘A’ conductor and it is connected to the ‘B’. Similarly, the magnetic field ‘B’ from the conductor ‘B’ can be connected to the ‘A’ conductor.

Cause of Proximity Effect
Cause of Proximity Effect

In the following diagram, when the two conductors carry current in a similar path, then the flow of current in the conductor can be distributed toward the utmost part of the conductors which is illustrated in the following diagram.
Likewise, once two conductors carry current in a reverse way, and then the flow of current within conductors will be distributed toward the internal facing of the conductors which is shown in the following figure.

The effects occurred in this are

  • The overall capacity of current-carrying can be reduced.
  • The resistance of AC can be increased.
  • Eddy current which is induced can cause losses within this system.

Different Factors

The different factors affecting the proximity effect mainly include material of conductors, structure, diameter, and frequency.


The Material used in the Conductors

If the conductors are designed with high ferromagnetic materials then this effect will be more on their surfaces.

Structure of the Conductors

As compared to the normal conductor like ACSR, this effect will be more over the solid conductors because the area of the surface on the normal conductor is lesser as compared with the solid type conductor.

Frequency of the Conductors

When the frequency of the conductor increases then the proximity will be increased.

The Diameter of the Conductors

When the diameter of the conductor increases then the effect of the conductors will be increased.

How to Reduce the Proximity Effect?

To reduce the effect of proximity, the ACSR conductor can be used because, in this type of conductor, the steel material can be arranged in the center of the conductor & the Aluminium conductor can be used around steel material.

The steel material in the conductor increases the strength of the conductor however reduces the area of the surface on the conductor. Therefore, the flow of current will be in the external layer of the conductor mostly. So there is no flow of current within the conductor. So that proximity effect can be reduced.

Thus, this is all about an overview of proximity effect, causes, and factors and how to reduce this effect. This effect is insignificant in transmission lines due to more space among the conductors whereas in cables the distance between two conductors is less. It mainly depends on various factors which are mentioned in the above. Here is a question for you, what are the pros & cons of proximity effect?