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Electrical Power Formula:
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Electrical power is the rate at which electrical energy is transferred by an electric circuit. The SI unit of power is the watt (W), which equals one joule per second. It's calculated by multiplying voltage by current, adjusted by the power factor in AC circuits.
The calculator uses the electrical 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: Calculating electrical power is essential for designing electrical systems, determining energy consumption, sizing components, and ensuring electrical safety.
Tips: Enter voltage in volts, current in amperes, and power factor (0 to 1). For DC circuits or purely resistive AC loads, 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 is the power factor (PF = P/S).
Q2: When is power factor not equal to 1?
A: In AC circuits with inductive or capacitive loads (motors, transformers, etc.), where current and voltage waveforms are out of phase.
Q3: How can I improve power factor?
A: By adding power factor correction capacitors to offset inductive loads, bringing the power factor closer to 1.
Q4: What's typical power factor for household appliances?
A: Resistive loads (heaters, incandescent lights) have PF=1. Motors typically have PF=0.8-0.9. Electronics with switching power supplies may have PF=0.6-0.7.
Q5: Why is power factor important?
A: Low power factor increases current for the same real power, leading to higher energy losses and requiring larger conductors. Utilities often charge penalties for low power factor.