This article provides detail about skin effect, How does the skineffect occur in an electrical conductor? and what are the parameters affecting skin effect in transmission lines?
Skineffect is one of the important topics of the power system. So read it up to a conclusion for better understanding.
A century ago. Sir Horace lamb proposed a paper describing the skin effect on spherical conductors and the famous mathematician and physicist Oliver Heaviside generalized this concept for all the shapes of electric conductors.
The proposed papers helped in designing the electrical transmission lines.
What is the skin effect in electrical?
The term "skin effect" refers to the flow of non-uniform AC current on the surface or skin of the conductor which increases the resistance, of the core in the solid conductor.
n the inner surface. It means the electric current will not flow in the core of the conductor but it flows outer surface of the conductor.
Skin effect in the transmission line.
What causes the Skin effect in electrical engineering?
Normally, skin effect occurs on alternating current (AC) due to electromagnetic effect (Non-uniform waveform). So the frequency of alternating current increases the skin effect.
The skin effect only occurs on AC current due to the Magnetic effect of electric current, also known as the Electromagnetic-inductance effect.
How does the skineffect occur in an electric conductor?
Alternating current (I) in a solid conductor creates a circular magnetic field (H) around the electrical conductor. According to the faradays law of electromagnetic induction, in a conductor, the varying magnetic field induces a current which is called induced currents. As a result, the induced current excites the secondary magnetic field at the edge of the conductor.
Due to
Now, According to Lenz's law, the time-varying magnetic field creates back emf that is opposing the electric field.
Due to the cancellation of magnetic flux, there will be flux linkage. This action increases the back emf at the center of the core and increases the impedance. It means, back emf increases ac impedance at the center of the conductor, due to internal and external flux linkage, as well as there will be a low impedance on the surface of the conductor.
As a result, the electric current will choose a low resistance path and starts to flow on the surface or skin of the conductor.
What is Skin depth?
Skin depth is a term that refers to the measurement of current density near the surface of the conductor.
Or
A conductor's skin depth is the depth to which current flows. Therefore, the total area of skin depth will be less at high frequency.
High frequency can cause less current flow in the transmission line.
Skin depth is indicated with the symbol δ(delta). The strength of the Current density will decrease at the center of the conductor.
Skin depth formula
Factors affecting the skin effect
There are four factors affecting the skin effect, and understanding this will help us to reduce the skin effect.
- Frequency
- Diameter
- The shape of the conductor
- Type of material
Frequency(Hz)
Alternating current with high frequency will increase the skin effect. Skin effect is directly proportional to the frequency.
Diameter (d) of the conductor
The diameter of the material also determines the skin effect. For large diameter, the skin effect will be more. The skineffect is directly proportional to the diameter of the material.
Shape of the condutor
- solid conductor-skin effect will be more.
- Stranded conductor- Skin effect will be less.
In a solid conductor, the effect will be more because more surface area will be available for the formation magnetic field.
In a stranded conductor, the effect will be less because less surface area will be available for the formation of the magnetic field. The stranded conductor is also known as a bundled conductor.
Type of material
Skin effect increases with the permeability of the material. The term "permeability" refers to the ability of the material to support the formation of the magnetic field. If permeability is higher then it supports more on the formation of magnetic field and increases the skin effect.
Permeability-electro magnetism.
How to reduce skin effect?
- By supplying alternating currents with less frequency(50Hz) on the conductor will dramatically decrease the skin effect.
- Skin effect can be minimized by keeping the diameter and frequency of the conductor equal to one centimeter and up to 50 Hz.
- Using bundled conductor or stranded conductor will decrease the skin effect by decreasing the space for the formation of the magnetic field. (ACSR-Bundled conductor)
- The conducting material with less or no permeability will reduce the skin effect. Material with less response to the magnetic field reduces the skin effect.
- Normally, In alternating current, the high voltage decreases the flow of current. So decreased current flow minimizes the flow of current.
Conclusion
In electrical engineering, the skin effect is the decrease in the flow of alternating current at the center of the conductor. This effect helps to research more about frequency(Hz). The paper proposed by Sir Horace Lamb was "On electrical motions in a spherical conductor" explains briefly the skin effect, but he proposed for only spherical shape conductor.
The famous physicist and mathematician Oliver Heaviside makes the concept widely applicable for all shapes of the conductor.
Do you think still skin effect occurs in transmission line?✋