The ones who are crazy enough to think they can change the world are the ones who do.- Steve Jobs
Some kind of energy(says thermal energy) is converted into electricity in power plants. Power plants are situated far away from industries, commercial centres, villages, residential colonies and even from your house. The generator used in power plants generate electricity at a particular voltage (says 11KV). The generated electricity with 11KV cannot be transmitted via transmission line to the user demanded areas(industries) as the losses in transmission will be more. The only way to reduce the losses occur in the transmission line is by stepping up the voltage level of generated electricity from 11KV to 220KV. By using step up transformer at the sending end , the voltage of the generated electricity can be easily step up from 11KV to 220KV. The power plant wherefrom electricity is transmitted via transmission line is called as sending end. Whereas the other end of the transmission lines where the electricity is received is called as receiving end. At the receiving end , a step down transformer is get used to step down the electricity from 220kV to 400V (for 3Փ ) or 230V(for 1Փ ) as consumers appliance prefer this voltage rating.
Basically, a transformer is a static device comprising coils coupled through a magnetic medium connecting two ports at different voltage levels in an electrical system allowing the transfer of electrical energy from one ports to the other via the magnetic field. The port(winding) from which the electrical energy is transfer is called as Primary winding. The port(winding) to which the electrical energy is transfered is called as Secondary winding. Normally, the primary winding of the transformer is connected to the supply or generating station. The secondary winding of the transformer is connected to the load (says fans,bulbs etc).
Transformer does not generate any electricity. Transformer only transforms and transfers electrical energy from one circuit to the other circuit. Volt-ampere rating (says power rating) of the transformer is same whether calculated on the primary winding or at the secondary winding. Frequency of the alternating voltage on both side of the transformer will not change.
Practically, A transformer has no moving parts, except tapchangers or cooling fan or pump motors. Thus the life of a transformer is normally dependent upon the life of insulation. To be fair, transformer never dies.It is usually killed, by some unusual stresses breaking down a weakened part leads to the end of a transformer life. The life of a transformer has ended when probability of its failure becomes too high. Practically speaking, prediction of probability of its failure is impossible. Thus we can't judge the life of a transformer.
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