1. What is Electric Motor Horsepower?

Horsepower (HP) is a unit of measurement for power that quantifies the rate at which work is done. For electric motors, it indicates the mechanical output power the motor can deliver.

2. How Does the Calculator Work?

The calculator uses the electric motor horsepower formula:

Where:

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

Explanation: The formula converts electrical power (considering power factor and efficiency) to mechanical horsepower.

3. Importance of Horsepower Calculation

Details: Calculating horsepower helps in selecting the right motor for an application, ensuring it can handle the required load without being oversized.

4. Using the Calculator

Tips:

• Measure voltage and current under typical operating conditions
• Typical power factor for motors: 0.8-0.95
• Typical efficiency for motors: 0.75-0.95 (75%-95%)
• For three-phase motors, multiply by √3 (1.732) for line-to-line voltage

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between HP and kW for motors?
A: 1 HP = 0.746 kW. HP is mechanical power, kW is electrical power input. The difference accounts for efficiency losses.

Q2: How does motor speed affect horsepower?
A: Horsepower = (Torque × RPM)/5252. At same horsepower, higher RPM means lower torque.

Q3: What's service factor in motor ratings?
A: It's a multiplier (e.g., 1.15) indicating how much above nameplate HP the motor can handle intermittently.

Q4: How to calculate for three-phase motors?
A: Use line-to-line voltage and multiply by √3 (1.732) in the formula.

Q5: Why is efficiency important?
A: Higher efficiency means less energy wasted as heat, reducing operating costs over motor lifetime.