Join 60,000+ competitive exam aspirants
or with email
Your Cart
SubtotalтВ╣0
TotalтВ╣0
Examoogle тАв User тАв info@examoogle.com тАв EE-2024-8821
Chapter 1 of 12 тАв Page 1 of 248ЁЯФТ Protected PDF тАв Watermarked
Join 60,000+ competitive exam aspirants
If variable part of annual cost on account of interest and depreciation on the capital outlay is equal to annual cost of electrical energy wasted in the conductor, the total annual cost is minimum and the corresponding size of conductor is the most economical. This statement is known as
LenzтАЩs law
KelvinтАЩs law
FaradayтАЩs law
OhmтАЩs law
KelvinтАЩs law
Kelvin's law states that the most economical size of a conductor is one for which the annual cost of energy lost due to resistance is equal to the annual interest and depreciation on the capital cost of the conductor. It is a fundamental principle in power system engineering used for the economic design of transmission and distribution lines.
Kelvin's law states that the most economical size of a conductor is one for which the annual cost of energy lost due to resistance is equal to the annual interest and depreciation on the capital cost of the conductor. It is a fundamental principle in power system engineering used for the economic design of transmission and distribution lines.
CtotalтАЛ=CfixedтАЛ+CvariableтАЛ тАФ Total annual cost of the conductor
CfixedтАЛтИЭA тАФ Interest and depreciation cost proportional to cross-sectional area A
CvariableтАЛтИЭA1тАЛ тАФ Energy loss cost inversely proportional to cross-sectional area A
As the cross-sectional area of a conductor increases, the capital cost (initial investment for interest and depreciation) increases linearly, while the resistance decreases, leading to a decrease in energy loss costs. The total annual cost curve is parabolic, with the minimum point achieved where the cost of energy loss intersects the cost of the conductor material.
Kelvin's law helps in achieving minimum total cost for overhead transmission lines.
The law considers interest, depreciation, and electrical losses.
The minimum point of the total cost curve defines the most economical conductor area.
This method is widely used for determining the conductor size in power distribution and transmission projects.
Minimizes the overall financial burden of building transmission lines.
Provides a systematic mathematical approach for economic design.
Does not account for corona loss which increases with conductor size.
Difficult to estimate future energy costs and interest rates accurately.
Standard conductor sizes available in the market might not match the theoretical value.
Design of overhead transmission lines.
Design of distribution feeders.
Selecting appropriate cable cross-sections for industrial power supply.
Lenz's Law relates to induced EMF and direction of current.
Faraday's Law describes electromagnetic induction.
Ohm's Law relates voltage, current, and resistance in a conductor.
Kelvin's law is primarily used for overhead lines, whereas for cables, dielectric loss is also a factor.
B is correct тАФ The statement defines Kelvin's law, which balances the investment cost against the operational loss cost to achieve minimal total expenditure.
Remember that while Kelvin's law targets the economic sizing of conductors, it serves as a foundational concept in the cost-benefit analysis of all electrical power infrastructure.