The Power of Power Transformers

It is well known that the function of the power transformer is to help transmit power, voltage conversion and isolation, so it has been widely used in power supply technology and power electronics technology.
The most basic type of power transformer consists of two sets of coils with wires wound together inductively coupled with each other. When an alternating current (with a known frequency) flows through one set of coils, an alternating voltage with the same frequency will be induced in the other set of coils, and the magnitude of the induced voltage depends on the coupling of the two coils and the magnetic alternating current. degree of chain.
Generally, the coil connected to the AC power supply is called the primary coil; the voltage across this coil is called the primary voltage. The induced voltage in the secondary coil may be larger or smaller than the primary voltage, which is determined by the turns ratio between the primary coil and the secondary coil. Therefore, power transformers are divided into step-up and step-down transformers. Most power transformers have a fixed iron core on which primary and secondary coils are wound. Due to the high magnetic permeability of iron, most of the magnetic flux is confined in the iron core. Therefore, the two sets of coils can obtain a relatively high degree of magnetic coupling.

In some transformers, the coil and the core are tightly coupled, and the ratio of the primary and secondary voltages is almost the same as the coil turns ratio of the two. Therefore, the turns ratio of the transformer can generally be used as a reference index for the step-up or step-down of the transformer. Because of this step-up and step-down function, the transformer has become an important accessory of the modern power system. Increasing the transmission voltage makes long-distance power transmission more economical. As for the step-down transformer, it makes the power application more diversified. It can be said that if there is no transformer, the industry cannot achieve the status quo of development.
Transformers are commonly used in various electronic equipment for the following reasons: to provide various voltage levels to ensure the normal operation of the system; to provide electrical isolation of parts operating at different potentials in the system; to provide high impedance to alternating current, but low impedance to direct current; Maintain or modify waveform and frequency response at different potentials. In addition to the small size of the power transformer, there is no clear dividing line between the power transformer and the electronic transformer. Generally, the power supply of the 60Hz power network is very large, and it may cover the capacity of half a continent. The power limitation of electronic devices is usually limited by the ability of rectification, amplification, and other components of the system, some of which are amplifying power, but if compared with the power generation capacity of the power system, it still belongs to the scope of small power.
Therefore, according to the size of the transmission power, power transformers can be divided into the following grades: high power: above 10kVA; medium power: 10kVA ~ 0.5kVA; low power: 0.5kVA ~ 25VA; micro power: below 25VA. It should be self-evident that the design of the power transformer is also different depending on the transmission power.