VA to kW Calculator

Converting VA (volt-amperes) to kW (kilowatts) is fundamental to understanding electrical power systems, equipment sizing, and energy consumption. This conversion bridges the gap between what equipment draws from the supply (apparent power) and what it actually uses for productive work (real power). The relationship depends entirely on power factor - the phase angle between voltage and current waveforms in AC systems.

Power Triangle Fundamentals: In AC circuits, three types of power exist simultaneously. Real power (P) in watts or kilowatts performs actual work - running motors, heating elements, producing light. Reactive power (Q) in VAR or kVAR oscillates between source and load, maintaining magnetic and electric fields without doing work. Apparent power (S) in VA or kVA represents the vector sum of real and reactive power - what the supply must provide. These form a right triangle where S² = P² + Q², with power factor being cos($\theta$) = P/S.

Power Factor Impact: Power factor quantifies how effectively electrical power is converted to useful work. Unity power factor (1.0) means all supplied power does useful work - typical for resistive loads like heaters. Lower power factors indicate reactive power presence - motors typically operate at 0.8-0.9 PF, meaning 10-20% of supplied power doesn't do useful work. This "lost" capacity still requires infrastructure sizing, causing inefficiencies and higher costs. Industrial facilities often pay penalties for power factors below 0.90-0.95.

Equipment Rating Considerations: Generators, transformers, and UPS systems are rated in kVA because this represents their maximum current-carrying capacity regardless of power factor. However, they deliver power in kW based on load power factor. A 100 kVA generator can supply 100 kW to resistive loads (PF=1.0) but only 80 kW to typical motor loads (PF=0.8). This distinction is critical for proper equipment specification and avoiding costly oversizing or dangerous undersizing.