1. What is Motor RPM Calculation?

The RPM (Revolutions Per Minute) calculation determines the rotational speed of an AC motor based on the frequency of the power supply and the number of poles in the motor. This is fundamental for motor selection and application in various industries.

2. How Does the Calculator Work?

The calculator uses the synchronous speed formula:

Where:

• \( RPM \) — Revolutions per minute
• \( Hz \) — Frequency of the power supply in Hertz
• \( p \) — Number of poles in the motor (always an even number)

Explanation: The formula calculates the synchronous speed of an AC motor, which is the theoretical speed at which the motor's magnetic field rotates.

3. Importance of RPM Calculation

Details: Knowing a motor's RPM is crucial for proper equipment selection, ensuring compatibility with driven equipment, and predicting performance characteristics like torque and power output.

4. Using the Calculator

Tips: Enter the power supply frequency in Hz and the number of poles in the motor. The number of poles must be an even number (2, 4, 6, etc.). Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What is synchronous speed vs actual speed?
A: Synchronous speed is the theoretical speed, while actual speed is slightly lower due to slip in induction motors. This calculator gives synchronous speed.

Q2: Why must poles be an even number?
A: AC motors always have pairs of magnetic poles (north and south), so the total number is always even.

Q3: What's the RPM for a 4-pole motor at 50Hz?
A: (120 × 50) / 4 = 1500 RPM (common for European industrial motors).

Q4: How does frequency affect motor speed?
A: Motor speed is directly proportional to frequency. Double the frequency = double the speed (for same number of poles).

Q5: Can this be used for DC motors?
A: No, DC motor speed depends on voltage and is not determined by this formula.