Home
Back
Power Formula:
| From: | To: |
The Power Watt Formula (P = V × I × PF) calculates the real power in an electrical circuit by multiplying voltage (V), current (I), and power factor (PF). It's fundamental in electrical engineering for determining power consumption and system design.
The calculator uses the power formula:
Where:
Explanation: For DC circuits or purely resistive AC circuits, PF = 1. For AC circuits with reactive components, PF represents the phase difference between voltage and current.
Details: Accurate power calculation is essential for circuit design, energy consumption estimation, electrical safety, and proper sizing of electrical components and wiring.
Tips: Enter voltage in volts, current in amperes, and power factor (1 for DC circuits). All values must be valid (voltage > 0, current > 0, 0 ≤ PF ≤ 1).
Q1: What's the difference between real, apparent, and reactive power?
A: Real power (P) does actual work, apparent power (V×I) is the product of RMS values, and reactive power results from phase shifts in AC circuits.
Q2: When is power factor not 1?
A: In AC circuits with inductive or capacitive loads (motors, transformers, etc.) where current and voltage waveforms are out of phase.
Q3: How to improve power factor?
A: Adding capacitors (for inductive loads) or inductors (for capacitive loads) to bring voltage and current back in phase.
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 power supplies often have PF=0.6-0.7.
Q5: Why is power factor important?
A: Low PF increases current for same real power, requiring larger conductors and causing greater losses. Utilities often charge penalties for low PF.