A. Overhead line
B. Power cable
C. DC transmission
D. None of the above
Answer: B. Power cable
Explanation:
The alternating magnetic flux produced in the conductor due to the current flowing through the neighboring conductor gives rise to the circulating current which increases the resistance of the conductor. This phenomenon is called the proximity effect.
The proximity is more in the case of power cable and underground line where the distance between the conductor is small.
This effect is negligible in the case of overhead transmission lines because the distance between the conductors is large.
The proximity effect is absent in the case of DC transmission because the frequency of DC transmission is zero.
The proximity effect depends upon the size of the conductor, spacing between the conductor, frequency and permeability of the conductor material.
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