Answer / saravanakumar

Whenever the voltage passing through a conductor exceeding
a certain value the air molecules around the conductor got
ionised. the ions moving in the atmosphere, they take
energy from the supply so a hissing noise will occur.. this
effct is called corona effect..

Answer / panda n.n

Due to corona.

Answer / tameshwar singh

At very high voltage the molecules across the conductor are
get ionnised and at certain level of voltage the air gets
breakdown and act as conducting medium, this voltage is
known as Disruptive critical voltage. At this voltage
arcing is formed across conductor & due to this phenomenon
hissing noise will occurs. This noise causes the radio
interferance in communication lines

Answer / sukhraj cheema

humming sound in high voltage transmission lines is because
of corona effect.because of high voltage the air around the
conductors is ionised and will cause a humming naise.

Answer / shah alam

the HT lines causes humming because of corna effect.when
the voltage of transmission lines increases too much to
produce electric field of magnitude of 10^7 v/m.That is
more than the electric field required to break the
intermolecular bond of the air molecules.Hence the air
particle around the lines get ionised and start moving
freely.and during this movement several collisions occur
and resulting a humming sound.

Answer / mridupawan,assam

hissing sound produce whenever Corona occurs. But the
continuous humming occurs in high voltage transmission line
is due to the hysteresis losses coused by alternate
magnetic reversal of the conductor molecule from north pole
to south pole and vice versa. Magnetic reversal took place
under the influence of alternating voltage.This is just like
the humming in a transformer core.

Answer / vijay patel

due to high voltage the produced electrical field cause break down the air and moist particle in to the ions and this efeect cause humming sound

Answer / prodip das

Ans. Corona effect & hysteresis loss

Answer / guest

because of hysteresis losses

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