Motor Amps Calculation Formula:
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The 20 horsepower motor amps calculation determines the electrical current required by a 20 horsepower three-phase motor based on voltage, power factor, and efficiency. This is essential for proper electrical system design and motor protection.
The calculator uses the formula:
Where:
Explanation: The formula converts mechanical power (horsepower) to electrical power requirements, accounting for three-phase power characteristics and motor efficiency.
Details: Accurate current calculation is crucial for proper wire sizing, circuit breaker selection, motor protection device setting, and overall electrical system safety and efficiency.
Tips: Enter voltage in volts, power factor as a decimal (0.0-1.0), and efficiency as a decimal (0.0-1.0). All values must be positive and within valid ranges for accurate results.
Q1: Why is the conversion factor 746 used?
A: 746 watts equals 1 horsepower, so 20 horsepower equals 14,920 watts of mechanical power output.
Q2: What is a typical power factor for motors?
A: Power factor typically ranges from 0.8 to 0.95 for three-phase induction motors, depending on motor design and load conditions.
Q3: What efficiency values are typical for motors?
A: Modern three-phase motors typically have efficiencies between 0.85 and 0.95, with higher efficiency motors available.
Q4: Why is √3 used in the formula?
A: √3 accounts for the phase relationship in three-phase power systems, converting line-to-line voltage to phase voltage.
Q5: Can this calculator be used for single-phase motors?
A: No, this formula is specifically for three-phase motors. Single-phase motor calculations use a different formula without the √3 factor.