Principle of transformer operation

A transformer transfers alternating electrical electrical energy, where frequency remains unchanged and the voltage and current parameters can be changed. Transformers are generally applied when it is necessary to provide the consumer with different voltage and current parameters than are provided by the electrical power source.

A transformer has at least 2 windings having galvanic separation. The windings are integrated onto a magnetic core with a physical form of columns linked by yokes through which the magnetic flux permeates. The windings reside on the core columns. The core material consists of metal sheets which are insulated from each other. 

1-phase transformer

The windings are identified as primary or secondary, depending on the direction of energy flow through the transformer. The primary winding absorbs energy from the power source, while the secondary winding delivers energy to the load. The ratio of primary to secondary winding turns (Z1/ Z2) is approximately equal to the ratio of primary to secondary voltage.
Voltage U1/ U2 and it is called the transformation ratio ϑ.

Transformer windings can have a cylindrical or disk form, depending on its intended use and properties.
Windings are usually made of copper, although aluminum is sometimes used.
The windings are separated from each other by means of:

  • basic insulation – for isolation transformers
  • additional or reinforced insulation – for separation transformers
    Depending on the degree of protection against electric shock the transformers can be made in three classes of protection ( I; II; III ).
    Depending on the cooling medium the transformers are divided into dry-type and oil transformers (cooled respectively with air or oil) and where circulation is natural or forced.