What are the working principles and main functions of the transformer

- Feb 29, 2020-

A transformer is a device that uses the principle of electromagnetic induction to change AC voltage. The main components are a primary coil, a secondary coil, and an iron core (magnetic core).


The main functions are: voltage conversion, current conversion, impedance conversion, isolation, voltage stabilization (magnetic saturation transformer), etc.


It can be divided into: power transformers and special transformers (electric furnace transformers, rectifier transformers, power frequency test transformers, voltage regulators, mining transformers, audio transformers, intermediate frequency transformers, high frequency transformers, impact transformers, instrument transformers, and electronic transformers) , Reactors, transformers, etc.).


Circuit symbols often use T as the beginning of the number. Examples: T01, T201, etc.


Transformer principle: A transformer consists of an iron core (or magnetic core) and a coil. The coil has two or more windings, of which the winding connected to the power source is called the primary coil, and the remaining windings are called secondary coils. It can transform AC voltage, current and impedance.


The simplest core transformer consists of a core made of soft magnetic material and two coils with different numbers of turns on the core. The role of the core is to strengthen the magnetic coupling between the two coils. In order to reduce the eddy current and hysteresis loss in the iron, the iron core is formed by lamination of painted silicon steel sheets; there is no electrical connection between the two coils, and the coils are wound by insulated copper wires (or aluminum wires).


One coil connected to AC power is called the primary coil (or primary coil), and the other coil connected to the electrical appliance is called the secondary coil (or secondary coil). The actual transformer is very complicated. There are unavoidable copper loss (heating of the coil resistance), iron loss (heating of the core), and magnetic leakage (air-closing magnetic induction wire). To simplify the discussion, only the ideal transformer is introduced here. The conditions for an ideal transformer to be established are: ignore the magnetic flux leakage, ignore the resistance of the primary and secondary coils, ignore the core loss, and ignore the no-load current (the current in the primary coil when the secondary coil is open). For example, when the power transformer is running at full load (the output power of the secondary coil) is close to the ideal transformer situation.