Once at the beginning of the last century in the United States was popular advertising on the subject of "silent servant". The question concerned electricity, or rather, its ability to silently perform various work. The General Electric Company sought in this way to draw the attention of consumers to household appliances. But if we touch upon the purely physical process of electricity, it turns out that it is not so “silent”. An example is the well-known transformer device, which is capable of emitting a rather loud hum. So why is the transformer buzzing?
How a transformer works
To understand this, it does not hurt to remember the school physics lesson, which describes the principle of the transformer. The transformer works on the basis of the law of electromagnetic induction. It includes coils wound with 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 kind of ring made of special ferromagnetic steel. The ring is called the core and is located inside the windings. The design itselfcore 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 an induction EMF in the secondary winding - a converted electric current.
The core material is divided into many micro-sections. In each such section without the presence of an input voltage, there is its own magnetic field, often directed oppositely 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. Now you can guess why the transformer is buzzing.
Magnetostriction effect
Since the field is variable, the core plates begin to shrink and stretch in time with it. This process is called magnetostriction. Such movements are made with a high frequency of 100 Hz, at a current frequency of 50 Hz, a vibration radiates into space, which has an audible range and is distinguishable by the human ear. In addition to the standard frequency, alternating current contains higher frequency harmonics. There are more of them, the more the transformer is loaded, and this, in turn, is a sharper and more audible vibration. That's why the transformer hums.
Other causes of transformer noise
But not all the reasons for the "talkativeness" of the transformer are hidden in magnetostriction. Why does a loaded transformer hum? Emit noise:
- Transformer windings. 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 a poorly wound coil, if the turns do not fit together well.
- Core plates. Why? The transformer hums very often when they fit poorly and have gaps between flat surfaces. Then, in addition to squeezing, there is noise from the ringing of metal.
- Defect or damage to the insulation of the copper wire. This can happen in the thickness of the winding where elevated temperatures occur. In this case, a spark may jump between the windings, accompanied by a click. The more powerful the discharge, the more characteristic and louder the sound.
- All loose parts in the transformer why? The transformer hums during operation as they rattle.
In order to avoid this shortcoming in transformers, noiseless type transformers have been developed. Their circuit is designed in such a way that the current frequency is converted (increased) to a level at which vibration is not perceived in the audio range. This is 10 kHz and above. Silent transformers are much smaller in size and weight than conventional ones.
Conclusion
In order not to ask yourself the question of why the transformer is buzzing, all powerful models need to be taken from high-quality, reputable manufacturers. Low-power ones are not so demanding on the accuracy of execution. But if still availablethe transformer makes noise during operation, you can try to eliminate it by tightening the plates with screws. Just try not to overdo it and not delaminate the core metal. If there are no bolts, use varnish or glue, which is poured into the core. Winding rattle can only be eliminated by rewinding them.
