1. What is Synchronous Speed?

The synchronous speed (N_s) is the speed of the rotating magnetic field in the stator of an induction motor. It depends on the frequency of the power supply and the number of poles in the motor.

2. How Does the Calculator Work?

The calculator uses the synchronous speed equation:

Where:

• \( N_s \) — Synchronous speed (RPM)
• \( f \) — Frequency of power supply (Hz)
• \( p \) — Number of poles in the motor

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

3. Importance of Synchronous Speed

Details: Synchronous speed is important for understanding motor performance, as the actual rotor speed will be slightly less than synchronous speed (slip speed). It helps in motor selection and performance analysis.

4. Using the Calculator

Tips: Enter frequency in Hz (typically 50 or 60 Hz) and number of poles (must be an even number, typically 2, 4, 6, or 8). All values must be valid (frequency > 0, poles ≥ 2).

5. Frequently Asked Questions (FAQ)

Q1: Why is synchronous speed important?
A: It determines the theoretical maximum speed of an induction motor and helps in understanding motor performance characteristics.

Q2: What is the relationship between poles and speed?
A: More poles result in lower synchronous speed. A 4-pole motor runs at half the speed of a 2-pole motor at the same frequency.

Q3: Why 120 in the formula?
A: The factor 120 comes from converting seconds to minutes (60) and accounting for the fact that each AC cycle produces two poles (60×2=120).

Q4: What is typical synchronous speed for 50Hz and 60Hz systems?
A: For a 4-pole motor: 1500 RPM at 50Hz, 1800 RPM at 60Hz. For a 2-pole motor: 3000 RPM at 50Hz, 3600 RPM at 60Hz.

Q5: Why doesn't the rotor reach synchronous speed?
A: The rotor always runs slightly slower (slip speed) to induce current in the rotor and produce torque.