Electrical Machines, 2nd Edition

1 Transformers

Nowadays, electrical power is generated for industrial and utility purposes by thermal power stations and large hydroelectric plants in the three-phase form at a frequency of 50 Hz (in India). The generated frequency in some other countries is 60 Hz. The generated voltage at the generating station is 6.6 kV, 11 kV or higher. For transmission purposes, it is required to step it up to a voltage of 132 kV or higher. Again, in urban and rural areas it is required to step it down to 3.3 kV and 6.6 kV, respectively, and 11 kV at the substation. For domestic purposes, it is required to step it down to 400 V or 230 V Three-phase transformers are used to step up the generated voltage before transmission of electrical power and also to step ...