I. What is a transformer?
A transformer is a static electrical device that uses the principle of electromagnetic induction to change the voltage of alternating current (AC). It is widely used in power plants, substations, various power consumption sites, and even the mobile phone charger beside you contains a small transformer.
II. Scope of Application
Power System: Electricity generated by power plants needs to be stepped up to 110kV, 220kV, or even higher for long-distance transmission. When it reaches the vicinity of users, it is stepped down to 380V/220V for residential and industrial use.
Industrial and Commercial Buildings: Factory equipment, elevators, data centers, etc., require converting the mains voltage to specific voltage levels.
Electronic Devices: Chargers and internal power adapters in household appliances are used to step down 220V to the low voltage required by the equipment.
Special Fields: Rail transit power supply, laboratory instruments, medical equipment, and other scenarios with high requirements for voltage stability.
III. Operating Principle
A transformer mainly consists of two parts:
Core: Made of stacked high-permeability silicon steel sheets, forming the magnetic circuit.
Windings: Two coils placed on the core—the primary winding (connected to the power source) and the secondary winding (connected to the load).
Its core principle is based on electromagnetic induction:
When an AC voltage is applied to the primary winding, the alternating current generates an alternating magnetic flux in the core.
This alternating magnetic flux simultaneously passes through both the primary and secondary windings.
According to Faraday's law of electromagnetic induction, an electromotive force is induced in both windings, and the magnitude of the voltage is proportional to the number of turns in each winding.
Formula: Primary Voltage / Secondary Voltage = Primary Turns / Secondary Turns
Therefore, by changing the turns ratio between the primary and secondary windings, voltage can be stepped up or down.
IV. Basic Characteristics
Only suitable for alternating current (AC); cannot change direct current (DC) voltage.
No rotating parts during operation, offering high reliability, but there are certain energy losses (mainly core losses and copper losses).
While voltage changes, current changes inversely. The input power is approximately equal to the output power (ignoring losses).
As a key device in the power system, the transformer ensures the safe, economical transmission and conversion of electrical energy throughout the entire process from generation to consumption.
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