Motor Horsepower Calculator

Motor Horsepower Formula:

\[ HP = \frac{V \times I \times PF \times \eta}{746} \]

Voltage (V):

volts

Current (I):

amps

Power Factor (PF):

(0-1)

Efficiency (η):

(0-1)

Motor Horsepower (HP):

Unit Converter ▲

Unit Converter ▼

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1. What is Motor Horsepower?

Horsepower (HP) is a unit of measurement for power, or the rate at which work is done. For electric motors, it represents the mechanical output power the motor can deliver. The electrical input power is converted to mechanical power with some losses due to inefficiency.

2. How Does the Calculator Work?

The calculator uses the motor horsepower formula:

\[ HP = \frac{V \times I \times PF \times \eta}{746} \]

Where:

\( V \) — Voltage (volts)
\( I \) — Current (amps)
\( PF \) — Power factor (unitless, 0-1)
\( \eta \) — Efficiency (unitless, 0-1)
746 — Conversion factor from watts to horsepower

Explanation: The formula calculates the input electrical power (V × I), adjusts for power factor (real vs. apparent power), accounts for motor efficiency, and converts watts to horsepower.

3. Importance of Horsepower Calculation

Details: Knowing a motor's horsepower is essential for proper motor selection, sizing for applications, energy efficiency analysis, and troubleshooting performance issues.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between brake horsepower and electrical horsepower?
A: Brake horsepower (BHP) is measured at the motor output shaft, while electrical horsepower is calculated from input power. This calculator gives BHP when using the motor's efficiency factor.

Q2: Why is power factor important?
A: Power factor accounts for the phase difference between voltage and current in AC circuits. A low PF means more current is required for the same real power.

Q3: What's a typical efficiency for electric motors?
A: Standard efficiency motors are typically 85-90%, while premium efficiency motors can reach 92-96%.

Q4: Can I use this for three-phase motors?
A: Yes, but you'll need to multiply by √3 (1.732) for three-phase power calculations.

Q5: How does motor speed affect horsepower?
A: Horsepower is directly related to torque and speed (HP = Torque × RPM / 5252). At the same horsepower, higher speed means lower torque.