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Power Formula:
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The power formula (P = V × I × PF) calculates electrical power in watts from voltage, current, and power factor. It's fundamental in electrical engineering and power system analysis.
The calculator uses the power formula:
Where:
Explanation: For DC circuits or AC circuits with purely resistive loads, the power factor is 1. For AC circuits with reactive components, the power factor accounts for phase difference between voltage and current.
Details: Accurate power calculation is essential for circuit design, electrical safety, energy efficiency analysis, and proper sizing of electrical components and systems.
Tips: Enter voltage in volts, current in amps, and power factor (1 for DC or resistive AC loads). All values must be valid (voltage > 0, current > 0, 0 ≤ PF ≤ 1).
Q1: What if I don't know the power factor?
A: For DC circuits, use 1. For AC circuits with resistive loads (like heaters, incandescent lights), you can typically use 1. For motors or inductive loads, consult specifications.
Q2: How does this differ from apparent power?
A: This calculates real power (watts). Apparent power (VA) is V × I without power factor, while reactive power (VAR) accounts for energy storage in reactive components.
Q3: Can I use this for three-phase systems?
A: For balanced three-phase systems, multiply by √3 (about 1.732). The formula becomes P = √3 × V × I × PF.
Q4: Why is power factor important?
A: Low power factor means more current is needed for the same real power, increasing energy losses in distribution systems. Utilities often charge penalties for low power factor.
Q5: What are typical power factor values?
A: Resistive loads: 1.0, Induction motors at full load: 0.85-0.90, Fluorescent lighting: 0.92-0.97, Arc furnaces: 0.7-0.85.