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Three-Phase Motor Current Formula:
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Three-phase motor current calculation determines the electrical current drawn by a three-phase motor based on its power rating, voltage, power factor, and efficiency. This is essential for proper circuit design and protection.
The calculator uses the three-phase current formula:
Where:
Explanation: The formula accounts for the three-phase power system characteristics and motor efficiency to calculate the actual current drawn from the supply.
Details: Accurate current calculation is crucial for selecting appropriate circuit breakers, wire sizes, overload protection, and ensuring safe operation of three-phase motors in industrial applications.
Tips: Enter power in kW, voltage in volts, power factor as decimal (0-1), and efficiency as percentage. All values must be positive and within valid ranges for accurate results.
Q1: Why is power factor important in current calculation?
A: Power factor represents the phase difference between voltage and current. Lower power factor means higher current for the same power, affecting system efficiency.
Q2: What is typical power factor for three-phase motors?
A: Typically ranges from 0.8 to 0.95 for induction motors, depending on motor size, load, and design.
Q3: How does efficiency affect current calculation?
A: Lower efficiency means more input power is required to deliver the same output power, resulting in higher current draw.
Q4: When should this calculation be used?
A: For motor selection, circuit design, protection device sizing, and energy consumption analysis in three-phase systems.
Q5: Are there limitations to this formula?
A: This provides full-load current. Starting current (inrush) can be 5-8 times higher and requires separate consideration for protection devices.