POWER TRANSFORMER
“A Power transformer is a static machine used for transforming power from one circuit to another circuit without changing Power and frequency”.Power transformers used between the generator and the distribution circuits, and these are usually rated at 500 KVA and above. Power systems typically consist of a large number of generation locations, distribution points, and interconnections within the system or with nearby systems, such as a neighboring utility. The complexity of the system leads to a variety of transmission and distribution voltages. Power transformers must be used at each of these points where there is a transition between voltage levels.
Importance of a Power Transformer:
Power is the product of current and voltage (P=V x I). For a given amount of power, a low voltage requires a higher current and higher voltage requires a lower current. Since metal conducting wires have a certain resistance, some power will be wasted as heat in the wires of the distribution system. This power loss is given by
P loss = R*I2
Thus, it is overall transmitted power is same and given the constraints of practical conductor sizes, a low-voltage, higher current based electricity distribution system will have a much greater power loss than a high voltage, low current based one.
Electrical power has passed through a series of transformers by time it finally reaches the consumer. Power transformers are available for step-up operation, primarily used at the generator and referred to as generator step-up transformers, and for step-down operation, mainly used to feed distribution circuits.
Power transformers come in a range of sizes from a palm-sized transformer inside mobile phones chargers to a huge Giga-volt-amperes rated unit used to interconnect parts of national power grid.