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For a long distance HV transmission line the receiving end voltage under on loaded condition is
Much lower than sending end voltage
Lower than sending end voltage
Equal to sending end voltage
Higher than sending end voltage
Higher than sending end voltage
In long-distance HV transmission lines, the receiving end voltage under no-load or lightly loaded conditions is higher than the sending end voltage due to the Ferranti effect ┬╖ This phenomenon occurs primarily due to the line capacitance, which draws a leading charging current through the line inductance, leading to a voltage rise at the receiving end.
In long-distance HV transmission lines, the receiving end voltage under no-load or lightly loaded conditions is higher than the sending end voltage due to the Ferranti effect ┬╖ This phenomenon occurs primarily due to the line capacitance, which draws a leading charging current through the line inductance, leading to a voltage rise at the receiving end.
VRтАЛ=VSтАЛcos(╬▓l)тИТISтАЛZcтАЛsin(╬▓l) тАФ General transmission line equation
IchтАЛ=j╧ЙCVSтАЛ тАФ Charging current due to shunt capacitance
The transmission line acts as a distributed parameter network consisting of resistance, inductance, and shunt capacitance ┬╖ At no-load, the capacitance draws a leading current (IchтАЛ) from the sending end ┬╖ As this current flows through the series line inductance (XLтАЛ), it produces a voltage drop that results in a receiving end voltage VRтАЛ higher than the sending end voltage VSтАЛ because the reactive drop components interact to 'boost' the voltage.
The Ferranti effect is significant only in long transmission lines (typically > 200 km).
It is primarily caused by the charging current flowing through the line inductance.
Shunt compensation using reactors is commonly used to mitigate this rise in voltage.
The effect is negligible in short lines because the capacitive effect is minor compared to resistive and inductive drops.
Self-regulation of voltage in specific load conditions
Reduces the requirement for extra compensation during light loading
Risk of insulation breakdown at the receiving end due to overvoltage
Requires additional reactive power compensation (shunt reactors) to maintain voltage stability
High Voltage (HV) and Extra High Voltage (EHV) overhead power transmission lines
The effect is directly proportional to the square of the line length.
Option B and A are incorrect because the voltage drop across the inductance in a light-load scenario actually leads to a voltage rise, not a drop.
D is correct тАФ The receiving end voltage is higher than the sending end voltage due to the Ferranti effect caused by the shunt capacitance of long transmission lines.
Always remember that while short lines always show a voltage drop at the load, long lines have capacitive characteristics that can cause the voltage to rise at the load end during light or no-load conditions.