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Power Equations:
This calculator helps you convert between electrical power (watts) and current (amps) using the fundamental power equation, taking into account voltage and power factor.
The calculator uses these equations:
Where:
Explanation: The equations show the relationship between power, voltage, current, and power factor in AC circuits.
Details: Power factor represents the ratio of real power to apparent power. In purely resistive loads, it's 1.0. For inductive or capacitive loads, it's less than 1.0, meaning more current is required for the same real power.
Tips: Select whether you want to calculate power or current. Enter the known values (voltage is always required). For DC circuits, use power factor = 1. For AC circuits, use the appropriate power factor (typically 0.8-0.95 for motors).
Q1: What's the difference between real power and apparent power?
A: Real power (watts) does actual work. Apparent power (VA) is the product of voltage and current. Power factor = Real Power / Apparent Power.
Q2: When should I use power factor = 1?
A: For DC circuits or purely resistive AC loads (like incandescent lights or heaters).
Q3: Why is my motor drawing more current than expected?
A: Motors have power factors less than 1 (typically 0.8-0.9), requiring more current for the same real power.
Q4: How do I measure power factor?
A: You need a power meter that can measure both real power (watts) and apparent power (VA).
Q5: What's a typical power factor for household appliances?
A: Resistive loads: 1.0, Motors: 0.8-0.9, LED lights: 0.5-0.9, Computers: 0.6-0.7.