Why hissing noise occur in transformer?

Answer 1

EHV and VHV substations tend to have a signature hum; this is due to small electrical arcs. This is normal. Most of the time this will not be audible on VHV and EHV power lines. If you are hearing this from the power line, it could be bad and the utility may want to know. It shouldn't be a risk to you, however the hum may be resulting from arcing, which can be fairly high frequency, which can mess with electronics's signals such as cell phones and radio (won't damage them, just bad reception).

Answer 2

A: Hissing is because is overheating before it destroy itself. But other noises are caused by loose lamination of the core.

B: Hissing noise is produced due to this reason but here is another important point is about frequency (e.g for 50 Hz) the core lamination face attractive and repulsive forces fifty times in one

cycle because frequency is 50 Hz.

Another Answer

The original answer is unnecessarily melodramatic. Transformers are fitted with protective devices that will disconnect the transformer long before a rise in temperature will cause it to 'destroy itself'!

'Hissing', as opposed to 'humming', is usually caused by the ionisation of air in the immediate vicinity of the transformer's high-voltage bushings (hollow insulators). This also manifests itself, after dark, as a blue-coloured luminous discharge.

'Humming', on the other hand, is due to something called 'magnetostriction', a distortion to the core laminations -exactly as described in the original answer, except that the attractive/repulsive forces are twice that of the supply frequency (i.e. 100 times, in the case of 50 Hz), together with harmonics based on that frequency.

Answer 3

due to corona loss at high voltage on line and insulation failoure beween conductors.these is see in high voltage lines i.e, means >400 Kv.

Answer 4

Usually a loose iron core or saturation of the core.

Answer 5

there have interference between T.V. and radio waves . for stopping this resistance is used in starter.