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Power Formula:
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Power calculation determines the rate at which electrical energy is transferred by an electric circuit. The basic formula for power in AC and DC circuits is P = V × I × PF, where P is power in watts, V is voltage, I is current, and PF is the power factor.
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 represents the phase difference between voltage and current.
Details: Accurate power calculation is essential for designing electrical systems, determining energy consumption, sizing electrical components, and ensuring electrical safety.
Tips: Enter voltage in volts, current in amperes, and power factor (between 0 and 1). For DC circuits or purely resistive AC circuits, use power factor = 1.
Q1: What's the difference between real power and apparent power?
A: Real power (P, in watts) is the actual power consumed, while apparent power (S, in VA) is the product of voltage and current. The ratio between them is the power factor.
Q2: When is power factor not equal to 1?
A: Power factor is less than 1 in circuits with inductive or capacitive loads (like motors, transformers, or fluorescent lighting) where current and voltage are out of phase.
Q3: How do I measure current and voltage?
A: Use a multimeter - connect in series for current measurement and in parallel for voltage measurement.
Q4: What's a typical power factor value?
A: Residential homes typically have 0.95-1.0, industrial motors might have 0.8-0.9, and heavily inductive loads could be as low as 0.5.
Q5: Does this formula work for three-phase power?
A: For three-phase systems, you need to multiply by √3 (about 1.732) when using line-to-line voltage: P = √3 × V × I × PF.