3-Phase Power Calculator
Real Power (Active):
0.00 kW
Apparent Power:
0.00 kVA
Reactive Power:
0.00 kVAR
Understanding 3-Phase Power Calculation
Three-phase electric power is a common method of alternating current (AC) electric power generation, transmission, and distribution. It is the most frequent method used by electrical grids worldwide to transfer power. It is also used to power large motors and other heavy loads.
In a balanced three-phase system, the power remains constant, which helps reduce vibration in large industrial motors. To calculate the power, we must consider the voltage (V), current (I), and the power factor (PF), which represents the phase shift between voltage and current.
The 3-Phase Power Formula
The standard formula to calculate the real power (P) in a balanced three-phase system using line-to-line voltage is:
P (Watts) = √3 × Voltage (V) × Current (A) × Power Factor (PF)
Where √3 (the square root of 3) is approximately 1.732.
Key Metrics Explained
- Real Power (kW): Also known as Active Power. This is the actual power used to perform work in a circuit.
- Apparent Power (kVA): The combination of real power and reactive power. It is the product of the root-mean-square (RMS) voltage and current.
- Reactive Power (kVAR): The power that oscillates between the source and the load without being "consumed." It is caused by inductive (motors, transformers) or capacitive loads.
- Power Factor: A ratio (0 to 1) representing how effectively the electricity is being used. A PF of 1.0 is ideal (purely resistive load).
Practical Example
Suppose you have an industrial motor running on a 480V three-phase supply. The measured line current is 50 Amps, and the motor has a power factor of 0.85.
- Apparent Power = 1.732 × 480 × 50 = 41,568 VA (or 41.57 kVA).
- Real Power = 41,568 × 0.85 = 35,332.8 Watts (or 35.33 kW).
- Reactive Power = √(41.57² – 35.33²) = 21.89 kVAR.