How To Calculate Power Consumption Of A Motor

Three-Phase Motor Power Formula:

\[ P = \sqrt{3} \times V \times I \times PF \times Eff \]

Voltage (V):

volts

Current (I):

amps

Power Factor (PF):

(0-1)

Efficiency (Eff):

Motor Electrical Input Power (P):

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1. What Is Motor Power Consumption?

Motor electrical input power represents the actual power consumed by a three-phase motor from the electrical supply, accounting for voltage, current, power factor, and motor efficiency.

2. How Does The Calculator Work?

The calculator uses the three-phase motor power formula:

\[ P = \sqrt{3} \times V \times I \times PF \times Eff \]

Where:

\( P \) — Electrical input power (watts)
\( V \) — Line voltage (volts)
\( I \) — Line current (amps)
\( PF \) — Power factor (0-1)
\( Eff \) — Motor efficiency (%)

Explanation: The formula calculates the real power consumed by a three-phase motor, considering the square root of 3 factor for three-phase systems and adjusting for power factor and efficiency losses.

3. Importance Of Power Calculation

Details: Accurate power consumption calculation is essential for electrical system design, energy cost analysis, motor selection, and determining appropriate circuit protection and wiring requirements.

4. Using The Calculator

Tips: Enter line voltage in volts, line current in amps, power factor as decimal (0-1), and efficiency as percentage. All values must be positive numbers within reasonable 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 into mechanical work, reducing energy losses and operating costs.

Q3: What is the difference between input and output power?
A: Input power is electrical power consumed, while output power is mechanical power delivered. The difference represents losses (heat, friction, etc.).

Q4: Can this calculator be used for single-phase motors?
A: No, this calculator is specifically for three-phase motors. Single-phase motors use a different formula without the √3 factor.

Q5: How accurate are typical motor efficiency values?
A: Modern motors have efficiency ratings from 85% to 97%. Actual efficiency depends on motor type, size, load conditions, and operating temperature.