According to Bureau of Indian Standard IS-1180 (Part 1, 4th Revision), A Distribution Transformer is a transformer that provides the final voltage transformation in the electric Power Distribution System, stepping down the voltage used in the distribution lines to the level used by the customers. The distribution line voltages are 3.3 kV, 6.6 kV, 11 kV, 22 kV and 33 kV in the country. The domestic supply for the consumers is 433 volt, 3 Phase (250 volt, 1 phase), 50 Hz. Transformer with primary voltages of 3.3, 6.6, 11, 22 or 33 kV and secondary voltage of 433 volt, 3 Phase (and 250 volt single phase) are called Distribution Transformers.
The purpose of a distribution transformer is to reduce the primary voltage of the electric distribution system to the utilization voltage serving the customer. In almost every place where people live and work you will find at least one transformer. But as long as it keeps working and supplying power to the every equipment in the public mall, the hotel, to the various offices, the oven in the cake store, the metal machinery or the petrochemical plant nobody gives it a second thought. These widely used transformers are designed for power centres, substations and networks to step down voltages at end customer points. They are used in public distribution systems, commercial buildings and industrial complexes as well