Answer / muthukumar

Because of high voltage the air molecules surrounding the HT
line are ionised.As the HT line carries AC current the
alternating magnetic field produced will cause the ionised
molecules to vibrate resulting in humming noise.

You can also consider the case that there will not be any
humming noise in case of HVDC transmission.

Answer / aruna devi

due to corona loss

Answer / kathirvel.r

Huming sound occured in HT AC Transmission only,Not in Dc
Transmission.Because, Corona Effect occured onlly for
AC.May i correct.

Answer / ilononurb

this is what we called Corona Effect. this is due to water
content of the air that sorroud in the transmission lines
that carrying high voltage ionization is taking place. So
humming sound is audible in the system.

Answer / subhash tp

The humming sound is coming from transformer
at the time of working is due the magnetic expansion
and de-expansion at the ends of transformer cores.
At the time of working the transfomer core ends are
expanding when supply voltage occures its positive half cycle
and the transformer ends are de-expanding at the time of supply voltage occures its negative half cycle .This expansion &de-expansion is making humming sound,and also this wii continue during the transformer is working.

Answer / oarhe ize

Because of the HEAT loss along the line.

What is the reason for using a GE G101 MCB in place of an EP102 MCB if both are capable of AC circuit protection?

0 Answers  

How to calculated capacitor rating both HT

10 Answers   Reliance,

What is the Relation b/w star delta starter , DOL starter and two speed starter. if we want to rotate a 20 kw fan in 2 speeds which type of two speed starter we have 2 use?

1 Answers   ABB,

what is the multi strand cable size? 0.45mm is area of one strand & 370nos of strand.

1 Answers  

WHY BREAKER ARE USED IN SUBSTATIONS?

0 Answers   Fedco,

why there is a phase difference between line voltage & phase voltage ?

4 Answers  

in HT service 3ph 4 wire service Y-phase voltage shows zero . whether it is meter fault? or what be the reason ? if y-ph voltage zero ,can current is recorded? reasons for failure?

0 Answers   apspdcl,

What is the use device of the grid.

1 Answers   Premier,

what is the difference between a hooter and a mcp

2 Answers  

What is vcb?

3 Answers  

how to calculate KA rating of C.B?explain with Formula.

1 Answers  

what will happen if i will done heart shape hole in transformer core?

1 Answers   Bhel, ONGC,