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3-Phase Motor Current Formula:
The motor current calculation formula estimates the current drawn by a three-phase AC motor based on its power rating, supply voltage, power factor, and efficiency. This is essential for proper circuit design and protection.
The calculator uses the 3-phase motor current formula:
Where:
Explanation: The formula accounts for the three-phase power system (√3 factor) and the motor's power factor and efficiency which affect the actual current draw.
Details: Accurate current calculation is crucial for selecting proper wire sizes, circuit breakers, overload protection, and ensuring safe operation of electrical systems.
Tips: Enter power in watts, voltage in volts, power factor (typically 0.8-0.95 for motors), and efficiency (typically 0.85-0.95). All values must be positive numbers within their valid ranges.
Q1: What's the difference between single-phase and three-phase current calculation?
A: Single-phase uses I = P/(V×PF×η) without the √3 factor. Three-phase is more efficient and common for industrial motors.
Q2: Why does power factor affect current?
A: Power factor represents the phase difference between voltage and current. Lower PF means more current is needed for the same real power.
Q3: What are typical power factors for motors?
A: Induction motors typically have 0.8-0.9 PF at full load, dropping at lighter loads. Synchronous motors can achieve unity (1.0) PF.
Q4: How does voltage affect current?
A: Current is inversely proportional to voltage for a given power. Higher voltage systems use less current for the same power.
Q5: When would I need to calculate motor current?
A: When sizing electrical components, troubleshooting performance issues, or verifying nameplate specifications.