Which of the following is a primary reason for changing voltage levels in substations?

The primary reason for changing voltage levels in substations is to reduce line losses during distribution. When electricity is transmitted over long distances, it encounters resistance within the conductors, which results in energy loss in the form of heat. By increasing the voltage for transmission, the current flowing through the wires is reduced, and since power loss due to resistance is proportional to the square of the current, higher voltage levels can significantly minimize these losses.

Additionally, after high voltage transmission over long distances, voltage is stepped down at substations to safe and usable levels for distribution to homes and businesses. This process not only enhances efficiency but also ensures that when electricity reaches its destination, it does so with minimal waste of energy, maximizing the effectiveness of the overall electrical system.

While other factors, such as efficiency in generation, simplification of circuit designs, and safety for end users, can be considerations in electrical design, the direct reduction of line losses during distribution is the most critical reason for adjusting voltage levels in substations.