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Three-Phase Power by Two Wattmeters Calculator

This calculator estimates the total active power in a three-phase system using the two-wattmeter method. It’s commonly used for both balanced and unbalanced load systems in electrical engineering. You can input line voltages, line currents, and the phase angle between voltage and current.

Two Wattmeters Power Measurement Tool

Input Fields
V₁₂
V
I₂
A
θ
°
V₁₃
V
I₃
A
If enabled, the result will update automatically when you change any value.

Two Wattmeter Method Power Formula

Formula
$$P = V_{12} \cdot I_2 \cdot \cos(30^\circ + \theta) + V_{13} \cdot I_3 \cdot \cos(30^\circ – \theta)$$

Where:

  • $$P$$ = Total active power (W)
  • $$V_{12}$$ = Voltage between line 1 and 2
  • $$V_{13}$$ = Voltage between line 1 and 3
  • $$I2, I3$$ = Line currents
  • $$ heta$$ = Phase angle between voltage and current

This method is effective for measuring power in three-phase three-wire systems, even under unbalanced conditions.


The two-wattmeter method is a widely used technique for measuring power in three-phase systems. It works for both balanced and unbalanced loads without needing a neutral connection. This calculator simplifies the process by allowing users to input line voltages (V12 and V13), currents (I2 and I3), and phase angle (θ). The result is the total active power in watts, which is essential for system monitoring and load analysis in electrical installations.

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