1. What is Motor Speed Calculation?

The motor speed calculation determines the rotational speed of an AC induction motor based on the electrical supply frequency and the number of magnetic poles in the motor. This is essential for motor selection and performance analysis.

2. How Does the Calculator Work?

The calculator uses the motor speed equation:

Where:

• \( RPM \) — Revolutions per minute
• \( f \) — Frequency of the power supply (Hz)
• \( p \) — Number of magnetic poles in the motor

Explanation: The equation shows that motor speed is directly proportional to frequency and inversely proportional to the number of poles.

3. Importance of RPM Calculation

Details: Knowing the motor speed is crucial for proper motor selection, system design, and ensuring the motor meets the requirements of the driven equipment.

4. Using the Calculator

Tips: Enter the power supply frequency in Hertz (Hz) and the number of poles in the motor (must be an even number). Typical values are 2, 4, 6, or 8 poles.

5. Frequently Asked Questions (FAQ)

Q1: Why is the number 120 used in the formula?
A: The factor 120 comes from converting seconds to minutes (60) and accounting for the fact that each complete AC cycle produces two poles (60 × 2 = 120).

Q2: What are typical motor speeds?
A: Common speeds for 60Hz systems: 3600 RPM (2-pole), 1800 RPM (4-pole), 1200 RPM (6-pole), 900 RPM (8-pole).

Q3: Does this work for DC motors?
A: No, this formula is specifically for AC induction motors. DC motor speed depends on different factors like voltage and load.

Q4: What is slip in motor speed?
A: Actual speed is slightly less than synchronous speed (calculated here) due to slip, typically 2-5% for induction motors.

Q5: Can I use this for variable frequency drives?
A: Yes, this shows the synchronous speed at any given frequency, though actual speed will be slightly less due to slip.