1. What is Motor RPM Calculation?

Motor RPM calculation determines the rotational speed of an AC motor based on the electrical frequency and number of magnetic poles. This formula calculates the synchronous speed - the theoretical maximum speed at which the motor would run if there were no slip.

2. How Does the Calculator Work?

The calculator uses the motor RPM formula:

Where:

• \( RPM \) — Rotational speed in revolutions per minute
• \( Freq \) — Electrical frequency in Hertz (Hz)
• \( Poles \) — Number of magnetic poles in the motor
• \( 120 \) — Constant conversion factor

Explanation: The formula calculates synchronous speed, which is the speed of the rotating magnetic field in the motor stator.

3. Importance of RPM Calculation

Details: Accurate RPM calculation is essential for motor selection, speed control applications, mechanical system design, and troubleshooting motor performance issues.

4. Using the Calculator

Tips: Enter frequency in Hz, number of poles (must be even number, typically 2, 4, 6, or 8). All values must be valid (frequency > 0, poles ≥ 2 and even).

5. Frequently Asked Questions (FAQ)

Q1: What is synchronous speed vs actual speed?
A: Synchronous speed is theoretical maximum; actual speed is slightly lower due to slip, which is necessary for torque production in induction motors.

Q2: Why must poles be an even number?
A: Magnetic poles always come in pairs (north and south) in AC motors, so the number must be even for proper magnetic field generation.

Q3: What are typical pole numbers?
A: Common configurations are 2-pole (3600 RPM at 60Hz), 4-pole (1800 RPM), 6-pole (1200 RPM), and 8-pole (900 RPM).

Q4: How does frequency affect motor speed?
A: Motor speed is directly proportional to frequency. Doubling frequency doubles the synchronous speed.

Q5: Can this be used for DC motors?
A: No, this formula applies only to AC synchronous and induction motors. DC motor speed depends on voltage and load characteristics.