Three Phase Motor Amps Formula:
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The three phase motor amps calculation estimates the current drawn by a 10 horsepower three phase motor based on voltage, power factor, and efficiency. This calculation is essential for proper electrical system design and motor protection.
The calculator uses the formula:
Where:
Explanation: The formula converts horsepower to electrical power requirements, accounting for the three-phase power system characteristics and motor performance factors.
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 and efficiency as decimal values (e.g., 0.85 for 85%). All values must be valid positive numbers within their respective ranges.
Q1: Why is the conversion factor 746 used?
A: 746 watts equals 1 horsepower, so 10 horsepower equals 7,460 watts of mechanical power output.
Q2: What are typical power factor values for motors?
A: Power factor typically ranges from 0.8 to 0.95 for three-phase motors, depending on motor size, type, and load conditions.
Q3: What are typical efficiency values for motors?
A: Motor efficiency typically ranges from 0.85 to 0.95 for modern three-phase motors, with higher efficiency in larger motors.
Q4: Why is √3 used in the formula?
A: √3 (approximately 1.732) is the mathematical constant used to convert between line-to-line voltage and phase voltage in three-phase systems.
Q5: How does voltage affect motor current?
A: Current is inversely proportional to voltage - higher voltage results in lower current for the same power output, which is why higher voltage systems are used for larger motors.