1. What is the 3 Phase Motor Speed Formula?

The 3 Phase Motor Speed Formula calculates the rotational speed of an AC induction motor based on the power supply frequency and the number of magnetic poles in the motor. This is fundamental for motor selection and application in industrial settings.

2. How Does the Calculator Work?

The calculator uses the motor speed equation:

Where:

• \( RPM \) — Revolutions per minute
• \( f \) — Power supply frequency in Hertz (Hz)
• \( p \) — Number of magnetic poles in the motor (always an even number)

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

3. Importance of Motor Speed Calculation

Details: Knowing a motor's speed is crucial for proper equipment selection, ensuring compatibility with driven machinery, and optimizing performance in applications like pumps, fans, and conveyors.

4. Using the Calculator

Tips: Enter the power supply frequency in Hz and the number of poles (must be an even number). Common pole configurations are 2, 4, 6, or 8 poles.

5. Frequently Asked Questions (FAQ)

Q1: Why is the number of poles always even?
A: AC induction motors require pairs of north and south poles, so the pole count is always an even number.

Q2: What are typical motor speeds?
A: For 60Hz systems: 3600 RPM (2-pole), 1800 RPM (4-pole), 1200 RPM (6-pole). For 50Hz systems: 3000 RPM, 1500 RPM, 1000 RPM respectively.

Q3: Why doesn't my motor run at exactly the calculated speed?
A: The formula gives synchronous speed. Actual speed is slightly less due to "slip" which allows torque production in induction motors.

Q4: Can I use this for single-phase motors?
A: The formula applies to single-phase motors too, but their performance characteristics differ significantly from three-phase motors.

Q5: How does variable frequency drive affect motor speed?
A: VFDs change the input frequency, allowing motor speed control according to this formula.