National Council of Examiners for Engineering and Surveying (NCEES) Fundamentals of Engineering (FE) Electrical and Computer Practice Exam

The formula for three-phase apparent power, denoted as S, is indeed represented as S = √3(IV). This formula arises from the nature of three-phase systems, which are commonly employed in electrical power distribution and machinery due to their efficiency and balanced load characteristics.

In a three-phase system, the power calculation incorporates the square root of three due to the geometry of the phase relationships between the three alternating currents and voltages. The I represents the line current, and V represents the line-to-line voltage.

Using this formula, the apparent power (measured in volt-amperes, VA) accounts for the total power flowing in the system, which is influenced not only by the current and voltage levels but also by the phase difference inherent in a three-phase configuration. The √3 factor is crucial as it reflects the conversion between line-to-line voltage (used in this context) and phase voltage in a balanced load situation.

This understanding is fundamental for engineers working with three-phase electrical systems, allowing for accurate calculations and effective system design, ensuring that equipment operates correctly and efficiently.