AC Power Calculator
Electrical engineering utility for computing Real (P), Reactive (Q), and Apparent (S) power in single and three-phase systems. Visualizes phase angles and power factor efficiency.
About
In Alternating Current (AC) systems, power flow is rarely a simple product of voltage and current due to the phase shift introduced by inductive or capacitive loads. Electrical engineers must calculate Real Power (usable energy), Reactive Power (stored/returned energy), and Apparent Power (total system capacity) to size conductors and transformers correctly. Miscalculating these values often leads to equipment overheating, inefficient energy usage, and utility penalties for poor Power Factor.
This tool solves the triangulation of the Power Triangle for both single-phase and three-phase balanced systems. It visualizes the Phase Angle, providing immediate feedback on system efficiency. The calculator distinguishes between line-to-line and line-to-neutral inputs, a common source of error in industrial load calculations involving induction motors or large capacitor banks.
Formulas
Calculations derive from the Power Triangle relationships using voltage (V), current (I), and the phase angle (φ). Power Factor (PF) is defined as cos(φ).
Real Power (P): P = VI × PF [Watts]
Reactive Power (Q): Q = VI × sin(arccos(PF)) [VAR]
Apparent Power (S): S = VI [VA]
Three-Phase Multiplier: For 3φ, multiply all by √3 (assuming line-line voltage).
The vector relationship is S2 = P2 + Q2.
Reference Data
| Load Type | Typical Power Factor (PF) | Phase Nature | Notes |
|---|---|---|---|
| Resistive Heater | 1.0 | Unity | Purely real power (P ≈ S) |
| Incandescent Lamp | 1.0 | Unity | Filament acts as resistor |
| Induction Motor (Full Load) | 0.85 - 0.90 | Lagging | High inductive reactance |
| Induction Motor (No Load) | 0.10 - 0.30 | Lagging | Mainly magnetizing current |
| Arc Welder | 0.35 - 0.80 | Lagging | Highly variable inductive load |
| LED Driver (Uncorrected) | 0.50 - 0.60 | Leading/Lagging | Non-linear switching load |
| Computer Power Supply | 0.60 - 0.75 | Lagging | Switch-mode harmonics |
| Fluorescent (Magnetic Ballast) | 0.40 - 0.60 | Lagging | Requires correction capacitor |