A transformer is a device that transforms alternating current (AC) voltage, current, and impedance. When an AC current flows through the primary coil, an AC magnetic flux is generated in the iron core (or magnetic core), inducing a voltage (or current) in the secondary coil. A transformer consists of an iron core (or magnetic core) and coils. The coils have two or more windings; the winding connected to the power source is called the primary coil, and the remaining windings are called the secondary coils.
A transformer is a common electronic component and electrical device. It can be used to transform an alternating voltage of a certain value into an alternating voltage of another value with the same frequency. It can also change the value of AC current, transform impedance, change phase, or change frequency.
Why are power transformers needed?
A power plant wants to transmit electrical power P=sqrt(3)*UIcosφ to the area where electricity is used. When P and cosφ are constant, the higher the voltage used, the smaller the current in the transmission line, thus reducing losses in the transmission line and saving conductive materials. Therefore, using high voltage for long-distance power transmission is the most economical. The highest voltage for AC power transmission in my country has reached 500kV. Such high voltages are unacceptable for generators to produce directly, both for safe operation and cost reasons. Generators typically output voltages of 3.15kV, 6.3kV, 10.5kV, and 15.75kV, requiring step-up transformers to increase the voltage for long-distance transmission.
Why are distribution transformers needed? After electricity is transmitted to the consumption area, it needs to be reduced to the required voltage level by transformers at various substations to meet the voltage requirements of the electrical equipment.