What does a step-up transformer do to the current for economical power transmission?

A step-up transformer is designed to increase the voltage of an electrical power supply while simultaneously reducing the current. This reduction in current is crucial for economical power transmission over long distances. The rationale behind this lies in the relationship between voltage, current, and power, which is represented by the formula: Power (P) = Voltage (V) × Current (I).

When the voltage is increased by a step-up transformer, it allows for the transmission of the same amount of power using a lower current. Lower current levels are advantageous in power transmission because they minimize resistive losses, often referred to as I²R losses, where I is the current and R is the resistance in the transmission line. These losses directly contribute to the inefficiency of power systems, as energy is lost as heat in the conductors.

By using a step-up transformer, utilities can transmit electricity over long distances at high voltages and low currents, thus optimizing the efficiency of the power delivery system, reducing costs associated with energy losses, and improving overall economic viability.