1. What is the Amperage from Horsepower Calculator?

Definition: This calculator determines the electrical current (amperage) required for a motor based on its horsepower rating and electrical characteristics.

Purpose: It helps electricians, engineers, and technicians properly size electrical components and wiring for motor installations.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( I \) — Current in amperes (A)
• \( HP \) — Horsepower rating of the motor
• \( V \) — Voltage of the electrical supply
• \( \eta \) — Motor efficiency (as a decimal, e.g., 0.9 for 90%)
• \( PF \) — Power factor (as a decimal, typically 0.8-0.95)

Explanation: The formula converts horsepower to watts (746W = 1HP), then divides by the product of voltage, efficiency, and power factor to find current.

3. Importance of Amperage Calculation

Details: Accurate current calculation ensures proper wire sizing, circuit breaker selection, and prevents electrical hazards from undersized components.

4. Using the Calculator

Tips: Enter the motor's horsepower, system voltage (default 480V), motor 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 - this converts mechanical power to electrical power.

Q2: What's a typical power factor for motors?
A: Most AC motors have power factors between 0.8 and 0.95, with 0.85 being common.

Q3: How do I find motor efficiency?
A: Check motor nameplate or manufacturer specifications. Typical values range from 0.8 to 0.95.

Q4: Does this work for three-phase motors?
A: This formula is for single-phase. Three-phase requires an additional factor of √3 (1.732).

Q5: Why is voltage important in this calculation?
A: Higher voltages require less current for the same power, following Ohm's Law (P = VI).