Why are high voltages used for long-distance power transmission?

High voltages are used for long-distance power transmission to reduce energy loss due to resistance in the wires.

In more detail, the transmission of electrical power over long distances involves the movement of electrical energy from the power station where it is generated to the end user. This process is not perfectly efficient, and some energy is lost as heat due to the resistance of the transmission wires. This energy loss is proportional to the square of the current flowing through the wires, as described by Joule's law.

By increasing the voltage at which the power is transmitted, the current required for a given amount of power is reduced, as power is the product of voltage and current (P=IV). This reduction in current results in a significant decrease in energy loss, as the energy loss due to resistance is proportional to the square of the current. Therefore, transmitting power at high voltages is more efficient for long-distance power transmission. Understanding the principles of equipotential surfaces and the properties of resistivity and conductivity can further elucidate why high voltages reduce losses.

Transformers are used at both ends of the transmission line to step up the voltage for transmission and step it down for use. The transformer operates on the principle of electromagnetic induction, where a changing magnetic field induces an electromotive force (EMF) in a nearby circuit. By adjusting the number of turns in the primary and secondary coils of the transformer, the voltage can be increased or decreased as required. This process is integral to both AC and DC transmission and the overall power grids and distribution systems.

In addition to reducing energy loss, using high voltages for long-distance power transmission also allows for the use of thinner wires, as less current is required for the same amount of power. This can result in significant cost savings in terms of materials and installation.

However, there are also safety considerations associated with using high voltages. High voltages can be dangerous, and appropriate insulation and safety measures must be in place to prevent accidents. Furthermore, the equipment required to handle high voltages, such as transformers and circuit breakers, can be expensive and complex.

In summary, high voltages are used for long-distance power transmission primarily to reduce energy loss due to resistance in the wires, but also to allow for the use of thinner, cheaper wires. However, this comes with increased safety considerations and equipment costs.