AC Power Calculation and the Power Triangle
In AC circuits, power is divided into three components based on the phase difference between voltage and current: "Active Power" (actual work), "Reactive Power" (energy oscillating between source and load), and "Apparent Power" (the total vector sum).
$$ \text{Apparent Power } S = V \times I = \sqrt{P^2 + Q^2} \quad [\text{VA}] $$
$$ \text{Active Power } P = S \times \cos\theta \quad [\text{W}] $$
$$ \text{Reactive Power } Q = S \times \sin\theta \quad [\text{var}] $$
Key Parameters
- Active Power (P): Real power consumed by resistive components. Unit: W (Watt).
- Reactive Power (Q): Energy stored in inductors or capacitors. Unit: var (Volt-Ampere Reactive).
- Apparent Power (S): Total power supplied by the source. Unit: VA (Volt-Ampere).
- Power Factor (cosθ): The ratio of active power to apparent power.
How to Use
- Enter at least two known values for the items you want to calculate.
- The tool works with combinations of V/I or Power components (P, Q, S).
- Click "Calculate" to derive all remaining values and visualize the Power Triangle on the right.
Frequently Asked Questions (FAQ)
Q. Why am I seeing an error?
A. Errors appear when inputs violate physical laws. For example, Active Power (P) cannot exceed Apparent Power (S) (i.e., P > S is theoretically impossible).
Q. Is this useful for Electrical Engineering studies?
A. Yes, it is ideal for understanding the power triangle and verifying textbook problems. The vector diagram helps visualize how phase shifts affect power.
Q. Does this support 3-Phase AC?
A. This tool is designed for Single-Phase AC. For 3-phase systems, you should apply values per phase or multiply the results by √3 as appropriate for your specific circuit.