Motor Speed Formula:
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Definition: This calculator determines the rotational speed (RPM) of an AC motor based on the electrical frequency and number of poles.
Purpose: It helps engineers, technicians, and electricians understand and predict motor performance characteristics.
The formula calculates synchronous speed:
Where:
Explanation: The formula gives the synchronous speed - the theoretical maximum speed before slip is considered.
Details: Knowing motor speed is crucial for proper equipment selection, performance prediction, and system design.
Tips: Enter the electrical frequency (typically 50 or 60 Hz) and number of poles (default 4). All values must be > 0.
Q1: What is synchronous speed?
A: The theoretical speed at which the motor's magnetic field rotates, before accounting for slip.
Q2: What's a typical number of poles?
A: Common configurations are 2, 4, 6, or 8 poles, with 4 being most common for standard motors.
Q3: Why 120 in the formula?
A: It comes from converting seconds to minutes (60) and accounting for the electrical cycle (2 poles per cycle).
Q4: How does this differ from actual motor speed?
A: Actual speed is typically 2-5% less due to slip, which allows the motor to produce torque.
Q5: What frequency should I use?
A: Use your local power frequency - 60 Hz in North America, 50 Hz in most other countries.