1. What is RPM?

RPM (Revolutions Per Minute) is a measure of the frequency of rotation, specifically the number of complete turns made in one minute. It's a crucial parameter for electric motors and rotating machinery.

2. How Does the Calculator Work?

The calculator uses the RPM formula:

Where:

• \( f \) — Frequency of the power supply (Hz)
• \( p \) — Number of poles in the motor
• 120 — Constant factor (60 seconds × 2 poles per revolution)

Explanation: The formula calculates the synchronous speed of an AC induction motor based on the frequency of the power supply and the number of magnetic poles in the motor.

3. Importance of RPM Calculation

Details: Knowing a motor's RPM is essential for proper equipment selection, performance analysis, and ensuring compatibility with driven machinery.

4. Using the Calculator

Tips: Enter the power supply frequency in Hertz (Hz) and the number of poles in the motor. Both values must be positive numbers.

5. Frequently Asked Questions (FAQ)

Q1: What's the difference between synchronous and actual RPM?
A: Synchronous RPM is theoretical speed, while actual RPM is slightly less due to slip in induction motors.

Q2: How do I determine the number of poles in a motor?
A: Check motor nameplate or divide 120 × frequency by the rated RPM (round to nearest even number).

Q3: Why is 120 used in the formula?
A: It combines 60 (seconds per minute) and 2 (poles per revolution in a single-phase system).

Q4: Does this work for DC motors?
A: No, DC motor speed depends on voltage and load, not poles and frequency.

Q5: What's a typical RPM range for AC motors?
A: Common speeds are 3600, 1800, 1200, and 900 RPM for 60Hz systems (2, 4, 6, and 8 poles respectively).