Electricity massively used in all spheres of modern life. When building distribution networks, which deliver an alternating electrical current to the consumer, it is better to use a high voltage. In a domestic networks are utilized for this nominal values 220 and 380 that realize good compromise between the relatively low losses and the possibility of using simple and cheap insulation materials.
This voltage is directly activated such loads as a cooker, a refrigerator and a washing machine. In contrast, low-voltage electrical consumers such as the recorder, the TV and the computer requires a constant current and voltage unit volts. It is produced in the outer drank integrated power supply.
Why buzzing transformer power supplies?
The power supplies of different equipment, regardless of their performance in the compulsory use one or more transformers.
They perform two main functions:
- reduce the voltage to a desired value;
- It provides galvanic isolation of the primary and secondary circuits, which are essential to the user electrical equipment.
In operation of such sources sometimes occurs hum characteristic. His main reason - magnitostrikatsiya. By this effect realize a noticeable change in the linear dimensions of magnetic materials when placed in a magnetic field. In schematic form, the effect of this field on the core shown in Figure 1.
Electrical iron, from which wafers are gaining transformer cores, just refers to materials with strong magnetic properties. Given the 50-hertz line voltage resizing converted into acoustic oscillations with a frequency close to 100 Hz, is well perceived by the human ear.
Separately, we note that the transformer pulse source operating at frequencies of 10 - 15 kHz. In this frequency range, hearing sensitivity is somewhat reduced, i.e. ceteris paribus modern compact sources operate significantly quieter, and the sound itself has a higher tone, which felt more like a whistling.
- level of acoustic noise during operation the transformer is typically proportional to its size;
- load value (given out current)
and also it depends on the material from which it is typed core.
Causes of hum and its elimination
Transformers which are mounted on power substations, because high power and design features emit well audible characteristic (for external casings, use of oil-cooling working pumps) hum.
Transformers home appliances usually work quietly enough at least by virtue of their small size. Therefore, the appearance of noticeable noise evidenced primarily on the mechanical design of a fault has arisen in its gaps between the individual plates.
Restore normal operation typesetting type transformers with E core can respective tightening screws. They are clearly visible in Figure 2. Clearances core shell type as shown in Figure 3, the selected worm plumbing yoke, which is applied directly to the housing. One of the variants of the clamp shown in Figure 3.
If the high level of noise accompanied by heating, it is a sign the inter-track circuit. In this situation, you need at least a corresponding fast winding.