How To Calculate Power Of AC Circuit

AC Real Power Formula:

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

Real Power (P):

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is AC Real Power?

AC real power (P) represents the actual power consumed by electrical equipment in an AC circuit. It is the portion of apparent power that performs useful work and is measured in watts (W).

2. How Does the Calculator Work?

The calculator uses the AC real power formula:

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

Where:

\( P \) — Real power in watts (W)
\( V \) — Voltage in volts (V)
\( I \) — Current in amperes (A)
\( \cos \phi \) — Power factor (dimensionless, 0-1)

Explanation: The formula calculates the actual power consumed by accounting for the phase difference between voltage and current in AC circuits.

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 infrastructure capacity.

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 numbers with power factor between 0-1 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, while apparent power (S) is the product of voltage and current. Apparent power is measured in VA (volt-amperes).

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 shifts between voltage and current.

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

Q4: What is a typical power factor value?
A: Residential power factors are usually 0.8-0.95, while industrial facilities with heavy motor loads may have power factors as low as 0.6-0.8.

Q5: Why do utilities charge for low power factor?
A: Utilities charge power factor penalties because low power factor requires larger conductors, transformers, and generation capacity to deliver the same real power.