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Examoogle • User • info@examoogle.com • EE-2024-8821
Chapter 1 of 12 • Page 1 of 248🔒 Protected PDF • Watermarked
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Apparent power is calculated by
VIcos∅
VIsin∅
VI
IR
VI
Apparent power, denoted as S, is the product of the RMS voltage and RMS current in an A.C. circuit, representing the total power delivered to the load. It is measured in Volt-Amperes (VA) and encompasses both real power (dissipated) and reactive power (stored and released).
Apparent power, denoted as S, is the product of the RMS voltage and RMS current in an A.C. circuit, representing the total power delivered to the load. It is measured in Volt-Amperes (VA) and encompasses both real power (dissipated) and reactive power (stored and released).
S=VI — Apparent power calculation
S=P2+Q2 — Relation in power triangle
In A.C. circuits, voltage and current may not be in phase due to reactive elements (inductors/capacitors). The total power 'seen' by the source is the Apparent Power S=VI. The real power is the projection of this apparent power on the real axis (P=VIcosϕ), while reactive power is the projection on the imaginary axis (Q=VIsinϕ).
Apparent power represents the maximum possible power that could be delivered if the circuit were purely resistive.
It is the vector sum of active (real) power and reactive power.
The ratio of real power to apparent power is defined as the Power Factor (PF=cosϕ).
Useful for sizing electrical equipment like transformers and cables.
Provides a measure of the total load demand on the supply system.
Does not indicate how much power is actually converted into useful work.
High apparent power with low real power indicates inefficient system utilization.
Rating of electrical transformers and generators (kVA rating).
Transmission line capacity analysis.
Option A (VIcosϕ) represents Real or Active Power.
Option B (VIsinϕ) represents Reactive Power.
Option D (IR) is not a standard power representation (Voltage drop is IR).
C is correct — Apparent power is the product of RMS voltage and RMS current, given by the expression S=VI.
Always remember that transformers and generators are rated in kVA (Apparent Power) because they are limited by current and voltage insulation limits, regardless of the load's power factor.