Answer / rajesh

In answer #2, Bhuwnesh Namdev has just copied from
wikipedia. While copying, has not even removed the refrence
nos. [1], [2],[3] etc. which appears along with the
explanations in wikipedia. What is appearing here is the
answer to the question "what is ferranti effect?". But here
the question is not that. The question is why Ferranti
effect does not occur at full load.
At light load, the line current is predominantly capacitive
in nature, hence it leads the voltage by almost 90 degrees,
so the voltage drop in the line impedance (which is
predominantly inductive) leads the source voltage by almost
180 degrees. So there is a voltage rise when you move
towards the receiving end. This is the Ferranti effect.
However, at full load, the current is predominantly
inductive(the power factor of the load in an Industry may
be taken as 0.8 lagging as a typical value). Therefor the
voltage drop in the line impedance (which is inductive) is
almost in phase with the source voltage.Hence the receiving
end voltage is less than the sending end voltage.

Answer / ippili varun kumar

ferranti effect occurs when no load or light load conditions,under this conditions receiving end voltage grater then sending end voltage.in another way the reactive power generated is more than reactive power absorbed. ferranti effect due to under light load condition line capacitance in phase with appilied voltage.  It only occurs in light medium or long transmission line .it is not present in short transmission line why because effect of capacitance negligible.but in case of under ground cables it present in short lines also due to high capacitance.

Answer / bhuwnesh namdev

The Ferranti Effect is a rise in voltage occurring at the
receiving end of a long transmission line, relative to the
voltage at the sending end, which occurs when the line is
charged but there is a very light load or the load is
disconnected.

This effect is due to the voltage drop across the line
inductance (due to charging current) being in phase with
the sending end voltages. Therefore both capacitance and
inductance are responsible for producing this phenomenon.[1]

The Ferranti Effect will be more pronounced the longer the
line and the higher the voltage applied.[2] The relative
voltage rise is proportional to the square of the line
length.[3]

Due to high capacitance, the Ferranti Effect is much more
pronounced in underground cables, even in short lengths.[4]

Answer / vishaljadhav001

When supply side C.B. switched,at receiving end voltage
will not appear immediately."Wavefront" is formed.At left
of wavefront Vtg & current occurs,but at right vtg &
charging current is zero.
This wavefront travels from left to right with wave velocity
(v) which depend upon how fast inductance,capacitance reach
max.current & current .At no load capacitor charge through
inductance step by step.When line charged Vr=2Vs.When load
is connected this capacitor discharged,so vtg appear at
load.so that ferrenti not occurs at full load.

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