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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. Power measures how much work can be done with a given electrical supply.
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, selecting appropriate wire sizes, determining circuit breaker requirements, and estimating energy consumption.
Tips: Enter voltage in volts, current in amperes, and power factor (between 0 and 1). For DC circuits or purely resistive AC loads, use power factor = 1. For inductive or capacitive loads, use the appropriate power factor.
Q1: What's the difference between real power and apparent power?
A: Real power (P, in watts) is the actual power consumed by the circuit. Apparent power (S, in VA) is the product of voltage and current. The ratio between them 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 waveforms are out of phase.
Q3: What's a typical power factor for household appliances?
A: Resistive loads (heaters, incandescent lights) have PF=1. Motors typically have PF=0.8-0.9. Electronic devices often have PF=0.6-0.7.
Q4: How does power factor affect energy bills?
A: Industrial users may pay penalties for low power factor. Residential users typically pay only for real power (watts) consumed.
Q5: Can power factor be greater than 1?
A: Normally no. Power factor ranges from 0 to 1. Values > 1 would indicate measurement errors or unusual conditions.