How to Calculate Motor Speed

The Motor Speed Calculator computes the synchronous speed for AC motors based on frequency and number of poles. The formula used is:

Where:

• \( N_s \): Motor speed in RPM.
• \( f \): Frequency in Hz.
• \( p \): Number of poles.

Enter the frequency and number of poles to calculate the synchronous speed in RPM.

Using the Motor Speed Calculator

This calculator is useful for electrical engineers and technicians to determine the synchronous speed of AC motors, which is essential for motor selection and system design.

Input the frequency (default: 60 Hz) and number of poles (default: 4). The calculator outputs the speed in RPM.

Example: Calculate speed for a motor with 60 Hz frequency and 4 poles.

1. Frequency: \( 60 \, \text{Hz} \)
2. Poles: \( 4 \)
3. Calculation: \( N_s = \frac{120 \times 60}{4} = 1800 \, \text{RPM} \)
4. Result: \( 1800 \, \text{RPM} \)

Use this tool for precise synchronous speed calculations in motor applications.

Common FAQ

Below are frequently asked questions about Motor Speed calculations:

• Q: What is synchronous speed?
  A: Synchronous speed is the speed at which the magnetic field rotates in an AC motor, calculated using the given formula.
• Q: Why is the constant 120 used?
  A: The 120 comes from 60 seconds per minute times 2 (for pole pairs), converting frequency to RPM.
• Q: Does this apply to all AC motors?
  A: This is for synchronous motors; induction motors run slightly slower due to slip.
• Q: What if the number of poles is odd?
  A: Number of poles is typically even (2, 4, 6, etc.), but the formula works for any positive integer.
• Q: How accurate is this calculator?
  A: It uses the standard formula, providing results rounded to 3 decimal places.