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Electrical Power Formula:
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The conversion from Volt-Amps (VA) to Watts (W) is essential in electrical engineering to determine real power consumption from apparent power. It accounts for the power factor which represents the efficiency of power usage.
The calculator uses the electrical power formula:
Where:
Explanation: The power factor represents the ratio of real power to apparent power, indicating how effectively current is being converted into useful work.
Details: A power factor of 1 means all power is effectively used (ideal case). Lower power factors indicate inefficiencies and may require power factor correction in industrial settings.
Tips: Enter VA value (must be positive) and power factor (between 0 and 1). Typical power factors: 1 for DC circuits, 0.95-1 for AC resistive loads, 0.6-0.8 for inductive loads.
Q1: Why is there a difference between VA and Watts?
A: VA measures apparent power (voltage × current), while Watts measure real power. The difference is due to phase differences in AC circuits.
Q2: What's a typical power factor for household appliances?
A: Resistive loads (heaters, incandescent lights) have PF≈1. Motors, fluorescent lights typically have PF 0.6-0.8. Electronics with power supplies often have PF 0.5-0.7.
Q3: When is power factor correction needed?
A: When large inductive loads cause low power factor (typically <0.85), increasing energy costs and requiring larger conductors.
Q4: Can power factor be greater than 1?
A: Normally no, except in unusual cases with non-sinusoidal waveforms where distortion power factor can create apparent values >1.
Q5: How does this relate to UPS sizing?
A: UPS systems are often rated in VA. To know runtime, convert VA to Watts using the load's power factor to estimate battery requirements.