Definition of Transformer
A transformer is a static machine used for transforming power from one circuit to another without changing frequency. This is a very basic definition of a transformer. Since, there is no rotating or moving part, so a transformer is a static device. Transformer operates on an ac supply. A transformer works on the principle of mutual induction.
History of Transformer
If we want to know the history of transformer we have to go back long in the 1880s. Around 50 years before that in 1830 the property of induction was discovered, and this is the working principle of a transformer. Later the transformer design was improved resulting in more efficiency and lesser size. Gradually the large capacity of transformers in the range of several KVA, MVA came into existence. In the year 1950, 400KV electrical power
transformer was introduced into high voltage electrical power system. In the early 1970s, unit rating as large as 1100 MVA was produced. Various manufacturers manufactured 800KV and even higher KV class transformers in the year of 1980.
Use of Power Transformer
Generation of electrical power in low voltage level is very much cost effective. Theoretically, this low voltage level power can be transmitted to the receiving end. This low voltage power if transmitted results in greater line current which indeed causes more line losses but if the voltage level of a power is increased, the current of the power is reduced which causes reduction in ohmic or I2R losses in the system, reduction in cross-sectional area of the conductor i.e. reduction in capital cost of the system and it also improves the voltage regulation of the system. Because of these, low-level power must be stepped up for efficient electrical power transmission.
This is done by a step-up transformer at the sending side of the power system network. As this high voltage power may not be distributed to the consumers directly, this must be stepped down to the desired level at the receiving end with the help of step down transformer. Electrical power transformer thus plays a vital role in power transmission.
Two winding transformers are generally used where a ratio of high voltage and low voltage is greater than 2. It is cost effective to use auto transformer where the ratio between high voltage and low voltage is less than 2. Again a single unit three-phase transformer is more cost-effective than a bank of three single phase transformers unit in a three-phase system. But a single three-phase transformer unit is a bit difficult to transport and have to be removed from service entirely if one of the phase winding breaks down.