AC Circuit Power Calculator

Single-Phase AC Power Formula:

\[ P = V \times I \times \cos \phi \]

Real Power (P):

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1. What is AC Circuit Power?

AC circuit power refers to the real power consumed in an alternating current circuit. Unlike DC circuits, AC power calculation must account for the phase difference between voltage and current, represented by the power factor (cos φ).

2. How Does the Calculator Work?

The calculator uses the single-phase AC power formula:

\[ P = V \times I \times \cos \phi \]

Where:

\( P \) — Real power (Watts)
\( V \) — Voltage (Volts)
\( I \) — Current (Amperes)
\( \cos \phi \) — Power factor (dimensionless, 0-1)

Explanation: The formula calculates the actual power consumed by the load, accounting for the phase relationship between voltage and current in AC systems.

3. Importance of Power Factor

Details: Power factor represents the efficiency of power usage. A power factor of 1 indicates perfect efficiency, while lower values indicate reactive power consumption that doesn't perform useful work but still requires current flow.

4. Using the Calculator

Tips: Enter voltage in volts, current in amperes, and power factor as a decimal between 0 and 1. All values must be positive, with power factor ranging from 0 to 1 inclusive.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between real power and apparent power?
A: Real power (P) is the actual power consumed and measured in watts. Apparent power (S) is the product of voltage and current (VA), while reactive power (Q) is the non-working power (VAR).

Q2: What causes low power factor?
A: Low power factor is typically caused by inductive loads like motors, transformers, and fluorescent lighting that create phase shift between voltage and current.

Q3: How can power factor be improved?
A: Power factor correction involves adding capacitors to counteract inductive reactance, bringing the power factor closer to 1 and reducing reactive power.

Q4: What are typical power factor values?
A: Residential: 0.85-0.95, Industrial: 0.75-0.85, Commercial: 0.80-0.90. Utilities often charge penalties for power factors below 0.90.

Q5: Does this formula work for three-phase systems?
A: No, for three-phase systems use: \( P = \sqrt{3} \times V_{L-L} \times I \times \cos \phi \) for line-to-line voltage or \( P = 3 \times V_{L-N} \times I \times \cos \phi \) for line-to-neutral voltage.