Power Calculator

Power Formula:

\[ P = V \times I \times \cos \phi \text{ (AC)} \quad \text{or} \quad P = V \times I \text{ (DC)} \]

Circuit Type:

Voltage (V):

Current (I):

Power Factor (cos φ):

(0-1)

Electrical Power (P):

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1. What is Electrical Power?

Electrical power is the rate at which electrical energy is transferred by an electric circuit. It is measured in watts (W) and represents the amount of work done or energy consumed per unit time in electrical systems.

2. How Does the Calculator Work?

The calculator uses the fundamental power formulas:

\[ P = V \times I \times \cos \phi \text{ (AC)} \quad \text{or} \quad P = V \times I \text{ (DC)} \]

Where:

\( P \) — Electrical power in watts (W)
\( V \) — Voltage in volts (V)
\( I \) — Current in amperes (A)
\( \cos \phi \) — Power factor for AC circuits (0-1)

Explanation: For DC circuits, power is simply the product of voltage and current. For AC circuits, the power factor accounts for the phase difference between voltage and current waveforms.

3. Importance of Power Calculation

Details: Accurate power calculation is essential for circuit design, energy consumption analysis, electrical safety, equipment sizing, and cost estimation in both residential and industrial applications.

4. Using the Calculator

Tips: Select circuit type (DC or AC), enter voltage in volts, current in amperes, and for AC circuits, provide the power factor (typically 0.8-1.0 for most applications). All values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is the difference between DC and AC power calculation?
A: DC power is simply V×I, while AC power requires multiplying by the power factor (cos φ) to account for phase differences between voltage and current.

Q2: What is power factor and why is it important?
A: Power factor represents the efficiency of power usage in AC systems. A lower power factor means more current is required to deliver the same amount of useful power, leading to energy losses.

Q3: What are typical power factor values?
A: Residential: 0.95-1.0, Industrial: 0.8-0.9, Motors at full load: 0.85-0.9. Unity (1.0) is ideal but rarely achieved in practice.

Q4: Can this calculator be used for three-phase systems?
A: This calculator is designed for single-phase systems. Three-phase power calculation requires additional factors and different formulas.

Q5: How does power relate to energy consumption?
A: Power (watts) × time (hours) = energy (watt-hours). To calculate electricity cost, multiply energy consumption by your utility's rate per kWh.