1. What is the Motor Speed Formula?

The motor speed formula calculates the rotational speed of an AC induction motor based on the electrical frequency and the number of magnetic poles in the motor. This relationship is fundamental in electrical engineering and motor design.

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 120 factor comes from converting seconds to minutes (60) and accounting for the fact that each AC cycle produces two poles (60 × 2 = 120).

3. Importance of RPM Calculation

Details: Knowing a motor's speed is crucial for proper application selection, mechanical design, and performance evaluation in industrial and commercial settings.

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: Why is the formula different for synchronous and induction motors?
A: This formula calculates synchronous speed. Induction motors typically run slightly slower (slip speed) due to load.

Q2: What are typical pole numbers for AC motors?
A: Common configurations are 2-pole (3600 RPM at 60Hz), 4-pole (1800 RPM), 6-pole (1200 RPM), etc.

Q3: How does voltage affect motor speed?
A: In induction motors, voltage affects torque but not synchronous speed. Speed is primarily determined by frequency and poles.

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

Q5: What's the relationship between Hz and RPM?
A: At 60Hz with 2 poles, synchronous speed is 3600 RPM. At 50Hz (common in Europe), it's 3000 RPM for 2-pole motors.