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Power Formula:
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The power formula (P = V × I × PF) calculates the real power in an AC electrical circuit. It takes into account the voltage (V), current (I), and power factor (PF) which represents the phase difference between voltage and current.
The calculator uses the power formula:
Where:
Explanation: For DC circuits or purely resistive AC loads, the power factor is 1. For inductive or capacitive loads, the power factor is less than 1, indicating that not all the apparent power is being converted to useful work.
Details: Accurate power calculation is essential for electrical system design, energy efficiency assessment, circuit protection sizing, and determining energy consumption.
Tips: Enter voltage in volts, current in amperes, and power factor (between 0 and 1). For DC circuits or purely resistive loads, use PF = 1. All values must be positive numbers.
Q1: What's the difference between real power and apparent power?
A: Real power (P, in watts) is the actual power consumed. Apparent power (S, in VA) is the product of voltage and current. The ratio P/S is the power factor.
Q2: When should I use a power factor less than 1?
A: Use PF < 1 for AC circuits with inductive (motors, transformers) or capacitive loads where current and voltage are out of phase.
Q3: What's a typical power factor value?
A: Residential: 0.95-1.0, Industrial: 0.8-0.9. Motors at full load: ~0.85, at light load: much lower.
Q4: How does power factor affect energy bills?
A: Some utilities charge commercial customers extra for low power factor since it increases current flow and system losses without delivering more useful power.
Q5: Can power factor be greater than 1?
A: No, power factor ranges from 0 to 1. Values > 1 would indicate measurement errors or incorrect calculations.