Final answer:
The main objective of electric power distribution systems is to transfer electrical energy efficiently, using high voltages to minimize losses and employing AC for the ease of transforming voltages for safe use.
Step-by-step explanation:
The overriding design objective for any electric power distribution system is to ensure the efficient transfer of electrical energy while minimizing losses. Transmitting power at high voltages over long distances is crucial because it reduces the current in the power lines, thereby minimizing Joule losses due to resistive heating.
Alternating current (AC) is typically used for power distribution systems because it can be easily increased or decreased in voltage by transformers, making it more efficient for long-distance transmission.
AC allows for power to be transmitted at high voltages, such as 330,000 volts, and later reduced by transformers at the point of use to safer, familiar values like 120V or 240V AC used in homes and businesses. This high-voltage transmission ensures that power losses are kept to a minimum, which is essential for an efficient and reliable electric supply.