1. What is Motor Current Calculation?

Definition: This calculator determines the electrical current required by an AC motor based on its horsepower rating and operating characteristics.

Purpose: Helps electricians and engineers properly size electrical circuits and components for motor applications.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( I \) — Current in amps
• \( HP \) — Motor horsepower rating
• \( V \) — Operating voltage (volts)
• \( \eta \) — Motor efficiency (0-1)
• \( PF \) — Power factor (0-1)

Explanation: Converts HP to watts (746W = 1HP), then divides by voltage and efficiency factors to get current draw.

3. Importance of Motor Current Calculation

Details: Accurate current calculation ensures proper wire sizing, circuit protection, and prevents equipment damage or safety hazards.

4. Using the Calculator

Tips: Enter motor HP, operating 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: 1 horsepower equals 746 watts, converting mechanical power to electrical power.

Q2: What's a typical power factor for motors?
A: Most AC motors have power factors between 0.8-0.9, but this varies with load and motor type.

Q3: How do I find motor efficiency?
A: Check motor nameplate or manufacturer specifications. Typical values range 0.85-0.95.

Q4: Does this work for 3-phase motors?
A: This calculates single-phase current. For 3-phase, multiply result by √3 (1.732).

Q5: Why is voltage important?
A: Higher voltage reduces current for the same power, allowing smaller conductors.