In the last issue the question of DC supplies was considered and how various components function when connected into a circuit supplied from a DC source. Now AC supplies will be discussed in a similar manner. The first question to answer is why are AC power supplies the main method of distribution? The short answer is that it is relatively easy to change its voltage, a process that is near impossible in the case of DC at higher power levels. This enables power to be transmitted from the power station at high voltage/low current and then used locally at a lower voltage/higher current. Transmitting power at a lower current means that there will be less power loss in the cables that will also be smaller and lighter making them much easier to install. DC would have to be generated and distributed at domestic voltages resulting in much higher currents having to pass over long distances. The component to establish the change in voltage is, no surprise I am sure, the transformer. At much lower voltages and current the transformer has also become an essential component in modern equipment.
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