Why the transformer is buzzing: causes and possibilities of eliminating noise

Once in the beginning of the last century in the US was popular advertising on the topic of "silent servant." The question concerned electricity, and, more precisely, its ability to silently perform various jobs. The company General Electric sought to attract consumers' attention to household appliances in this way. But if you touch the purely physical process of electricity, then it turns out that it is not so "silent". An example is the well known device transformer, which is capable of producing a rather loud rumble. So why the transformer is buzzing?

How does the transformer work?

To understand this, do not stop to remember the school lesson in physics, which describes the principle of the transformer. The transformer operates on the basis of the law of electromagnetic induction. It includes coils wound with a wire of different diameters and with a different number of turns. These coils represent the primary and secondary windings of the transformer. There is a connection between the windings. It is carried out by means of a peculiar ring of special ferromagnetic steel. The ring was called the core and is located inside the windings. The core design itself is assembled from thin plates.

When an alternating current is applied to the primary winding, it creates a magnetic field in the core. This field also changes according to the law of change of the current that generated it. In turn, the field induces the EMF induction in the secondary winding - the converted electric current.

The core material is divided into a number of micro-regions. In each such section, without an input voltage, there is its own magnetic field directed often opposite to each other. However, under tension, all flows begin to rush in one direction, creating a powerful magnet. All this is accompanied by a change in the physical dimensions of the core itself. You can guess now why the transformer is buzzing.

The effect of magnetostriction

Since the field is variable, then the core plates begin to contract and stretch out in time with it. This process is called magnetostriction. Such motions are made with a high frequency of 100 Hz, with a frequency of current of 50 Hz, vibration emanating from the sound field and distinguishable by the human ear. In addition to the standard frequency, there are higher frequency harmonics in the AC configuration. There are more of them, the more the transformer is loaded, and this in its turn is a sharper and audible vibration. That's why the transformer is buzzing.

Other causes of noise in the transformer

But not all of the reasons for the "talkativeness" of the transformer are concealed in magnetostriction. Why is the loaded transformer buzzing? Noise is allocated:

• Winding of the transformer. This is due to the fact that the magnetic flux is trying to displace the windings relative to the core. The sound is amplified in the case of an inadequately wound coil, if the loops do not fit well together.
• Core plates. Why? The transformer buzzes very often when they are poorly adjusted and have gaps between flat surfaces. Then, apart from squeezing, there is a noise from the sound of metal.

• Defect or damage to copper wire insulation. This can happen in the thickness of the winding, where there are elevated temperatures. In this case, a spark can jump between the windings, followed by a click. The more powerful the discharge, the more characteristic the sound is and louder.
• All poorly fixed parts in the transformer why? The transformer hums when working, as they are rattling.

In order to avoid this shortcoming in transformers, transformers of noiseless type have been developed. Their circuit is constructed in such a way that the current frequency (increase) is converted to a level at which vibration is not perceived in the sound range. This is 10 kHz and higher. Noiseless transformers are much smaller in size and weight than usual.

Conclusion

In order not to ask yourself why the transformer is buzzing, all the powerful models need to take quality, proven manufacturers. The low-power are not so demanding of the accuracy of execution. But if the existing transformer still produces noise during operation, you can try to eliminate it by tightening the plates with screws. Only try not to overdo it and break the metal core. If there are no bolts, use a lacquer or glue to fill the core. Eliminate the rattling of windings only by rewinding them.