1. What is the Electric Motor Speed Formula?

The electric motor speed formula calculates the rotational speed (in RPM) of an AC induction motor based on the power supply frequency and the number of magnetic poles in the motor. This fundamental relationship helps in motor selection and performance analysis.

2. How Does the Calculator Work?

The calculator uses the synchronous speed formula:

Where:

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

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

3. Importance of Motor Speed Calculation

Details: Knowing the synchronous speed is essential for proper motor selection, understanding motor performance characteristics, and ensuring compatibility with driven equipment.

4. Using the Calculator

Tips: Enter the power supply frequency in Hz and the number of poles (must be an even number). Standard frequencies are 50Hz or 60Hz depending on region.

5. Frequently Asked Questions (FAQ)

Q1: What is synchronous speed vs actual speed?
A: Synchronous speed is theoretical; actual speed is slightly less due to slip (typically 2-5% less for induction motors).

Q2: Why must poles be even numbers?
A: Magnetic poles always come in pairs (north and south), so the number must be even (2, 4, 6, etc.).

Q3: What are typical pole numbers?
A: Common configurations are 2-pole (3600 RPM at 60Hz), 4-pole (1800 RPM), 6-pole (1200 RPM), etc.

Q4: Does this work for DC motors?
A: No, this formula is for AC induction motors. DC motor speed depends on voltage and load.

Q5: How does voltage affect speed?
A: In induction motors, voltage affects torque but not synchronous speed (which depends only on frequency and poles).