A transformer transfers electrical energy between two circuits.
The iron core transformer symbol is 2 coils separated by two vertical lines symbolize the magnetic circuit.
Normally made up of two coils of wire wrapped around a core. These coils are called primary and secondary windings. Energy is transferred by mutual induction caused by a changing electromagnetic field.
If the coils have different number of turns around the core, the induced voltage in the secondary coil will be different from the first.
History of the Transformer
Transformers are based on the theory of electromagnetic induction, which was discovered by Michael Faraday in 1831, the first commercial model was introduced at the end of the design in 1885 by William Stanley.
Types of Transformer
The two main types of transformers are laminated and toroidal cores.
- Laminated cores are those common cube-shaped transformers, which are mostly used in Power Supplies. They are stronger, suitable for industrial use and cheaper than the toroidal.
- Toroidal are smaller and lighter, with the same power. They produce less electrical noise and are more efficient. The secondary winding can be joined in series to double the voltage or joined in parallel to obtain a higher current.
Other types of transformers are:
- Voltage reducer reduces the voltage to adapt them to the use of the appliance to be powered. Most electronic devices in homes make use of these transformers.
- Variac or Variables take a fixed voltage line (at the input) and provide a variable output voltage adjustable within two values.
- Isolation transformer mainly used as a protective measure, in work groups directly with the mains voltage and for coupling signals in electro-medical equipment and where stable voltages are needed.
- Power transformers sometimes incorporate a fuse that cuts the primary circuit when the transformer reaches an excessive temperature, preventing it from burns, fumes and gases, which poses the risk of fire. These fuses are usually not replaceable.
- Audio transformers are used to amplify signals and speakers.
- Electronic transformer consisting of an electronic circuit that increases the frequency of the electric current supplied by the transformer, they are part of more complex circuits that maintain the output voltage at a predetermined value regardless of the input variation, called switching power supply