Calculate Motor Horsepower From Amps

Three-Phase Motor Horsepower Formula:

\[ HP = \frac{V \times I \times \sqrt{3} \times PF \times Eff}{746} \]

Voltage (V):

volts

Current (I):

amps

Power Factor (PF):

(0-1)

Efficiency (Eff):

(0-1)

Motor Horsepower (HP):

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1. What Is Three-Phase Motor Horsepower Calculation?

The three-phase motor horsepower calculation determines the mechanical power output of an electric motor based on electrical input parameters. It converts electrical power to mechanical horsepower, accounting for motor efficiency and power factor.

2. How Does The Calculator Work?

The calculator uses the three-phase motor horsepower formula:

\[ HP = \frac{V \times I \times \sqrt{3} \times PF \times Eff}{746} \]

Where:

\( V \) — Voltage (volts)
\( I \) — Current (amps)
\( \sqrt{3} \) — Three-phase power constant (approximately 1.732)
\( PF \) — Power Factor (0-1)
\( Eff \) — Efficiency (0-1)
\( 746 \) — Conversion factor from watts to horsepower

Explanation: This formula calculates the actual mechanical power output by considering both the apparent power (V×I) and the motor's efficiency in converting electrical to mechanical energy.

3. Importance Of Horsepower Calculation

Details: Accurate horsepower calculation is essential for motor selection, load matching, energy efficiency analysis, and proper system design in industrial applications.

4. Using The Calculator

Tips: Enter voltage in volts, current in amps, power factor (typically 0.8-0.95 for motors), and efficiency (typically 0.85-0.95). All values must be positive and 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 require power factor correction.

Q2: How does motor efficiency affect horsepower?
A: Higher efficiency means more electrical power is converted to mechanical power, resulting in higher horsepower output for the same electrical input.

Q3: What are typical power factor values for motors?
A: Most three-phase motors have power factors between 0.80-0.95 at full load, decreasing at lighter loads.

Q4: Can this formula be used for single-phase motors?
A: No, single-phase motors use a different formula: HP = (V × I × PF × Eff) / 746 (without the √3 factor).

Q5: Why is the conversion factor 746?
A: 746 watts equals 1 horsepower, based on James Watt's original definition of mechanical horsepower.