1. What is a Motor HP to Amps Calculator?

Definition: This calculator converts motor horsepower to electrical current (amps) based on voltage, efficiency, and power factor.

Purpose: It helps electricians and engineers determine the current draw of electric motors for proper circuit sizing and protection.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( I \) — Current (amps)
• \( HP \) — Horsepower
• \( V \) — Voltage (volts)
• \( \eta \) — Motor efficiency (0-1)
• \( PF \) — Power factor (0-1)

Explanation: The formula converts mechanical power (HP) to electrical power (watts) using the 746 watts/HP conversion factor, then calculates current based on electrical power, voltage, efficiency, and power factor.

3. Importance of Current Calculation

Details: Proper current calculation ensures correct wire sizing, circuit breaker selection, and prevents electrical hazards like overheating.

4. Using the Calculator

Tips: Enter the motor horsepower, voltage (default 480V), efficiency (default 0.9), and power factor (default 0.85). All values must be > 0.

5. Frequently Asked Questions (FAQ)

Q1: Why 746 in the formula?
A: 746 watts equals 1 horsepower, converting mechanical power to electrical power.

Q2: What's a typical motor efficiency?
A: Standard motors range from 0.85-0.95 efficiency, with higher efficiency for premium motors.

Q3: What affects power factor?
A: Induction motors typically have 0.8-0.9 PF at full load, lower at partial loads.

Q4: How does voltage affect current?
A: Higher voltage reduces current for the same power (inverse relationship).

Q5: Should I add a safety factor?
A: Yes, consider adding 25% to the calculated current for startup surges and safety margins.