Electric Motor Power Formula

Three-Phase Electric Motor Power Formula:

\[ P = \sqrt{3} \times V \times I \times \cos \phi \times \text{Eff} \]

Voltage (V):

Current (I):

Power Factor (cos φ):

unitless

Efficiency (Eff):

unitless

Electrical Input Power (P):

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1. What is the Electric Motor Power Formula?

The three-phase electric motor power formula calculates the electrical input power required by a three-phase motor. It considers voltage, current, power factor, and efficiency to determine the actual power consumption.

2. How Does the Calculator Work?

The calculator uses the three-phase power formula:

\[ P = \sqrt{3} \times V \times I \times \cos \phi \times \text{Eff} \]

Where:

\( P \) — Electrical input power (Watts)
\( \sqrt{3} \) — Constant for three-phase systems (approximately 1.732)
\( V \) — Line voltage (Volts)
\( I \) — Line current (Amperes)
\( \cos \phi \) — Power factor (unitless, 0 to 1)
\( \text{Eff} \) — Motor efficiency (unitless, 0 to 1)

Explanation: This formula accounts for the phase relationship in three-phase systems and the efficiency losses in the motor.

3. Importance of Electrical Power Calculation

Details: Accurate power calculation is essential for proper motor sizing, energy consumption analysis, electrical system design, and cost estimation in industrial applications.

4. Using the Calculator

Tips: Enter line voltage in volts, line current in amperes, power factor (typically 0.8-0.95 for motors), and motor efficiency (typically 0.8-0.95). All values must be positive and within valid ranges.

5. Frequently Asked Questions (FAQ)

Q1: What is power factor and why is it important?
A: Power factor represents the ratio of real power to apparent power. Low power factor indicates poor electrical efficiency and may result in utility penalties.

Q2: How does motor efficiency affect power consumption?
A: Higher efficiency motors convert more electrical energy to mechanical work, reducing energy costs and heat generation.

Q3: What is the difference between single-phase and three-phase power?
A: Three-phase systems are more efficient for industrial applications, providing constant power delivery and requiring less conductor material for the same power output.

Q4: When should this formula be used?
A: This formula is specifically for three-phase AC motors. For single-phase motors, different formulas apply.

Q5: How accurate is this calculation?
A: The calculation provides theoretical input power. Actual power may vary due to operating conditions, temperature, and motor load variations.