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Why Transformers Are Needed for Voltage Transmission in Electrical Machines
Transformers change the voltage level of AC electric power, and they are needed because transmitting power at high voltage cuts the energy lost in power lines, while generating and using power both require much lower, safer voltages. This is part of electrical machine theory: transmission-line power loss is proportional to line length divided by voltage squared, so raising voltage before transmission and lowering it again at the load reduces loss without changing the power delivered. Transformers work by magnetic coupling between windings rather than mechanical motion, which is why, unlike motors or generators, they are not classified as electromechanical energy conversion devices.