The alternating
current flows near the surface of the conductor is known as skin effect.
Effect of Direct
current and Alternating current
- When direct current passes through conductor, current is uniformly distributed over the cross section of the conductor.
- However, an alternating current passes through conductor, current is non – uniformly distributed over the cross section of the conductor.
- More current flows towards the outer portion of conductor and less current flows through center of the conductor.
- The effective cross section of the conductor through current flows reduces due to skin effect this will effect in resistance of the conductor increases when alternating current flows through it.
Explanation of Skin effect
- When alternating current passes through center of the conductor, the flux through center of the conductor is higher than that of outer portion of the conductor.
- This will result in higher inductance at the center as compared to outer portion of the conductor resulting higher current flows through outer portion and less current passes through center of the conductor.
Main reason of Skin effect
Higher
inductance at the centre and lower inductance at the outer portion of the
conductor
Factor affecting Skin effect
( 1 ) Material of
conductor
( 2 ) Diameter of
conductor
- As the diameter of conductor increases, the skin effect also increases.
( 3 ) Frequency
- The skin effect increases as the frequency of supply increases because the reactance of conductor ( XL = 2πfL ) increases as the supply frequency increases.
- The skin effect is very less for low frequency supply.
( 4 ) Shape of
conductor
- Higher for solid conductor whereas less for stranded conductor
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