1. What is Synchronous Speed?

Synchronous speed (N_s) is the speed of the rotating magnetic field in the stator of a synchronous 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 formula:

Where:

• \( N_s \) — Synchronous speed in RPM (revolutions per minute)
• \( f \) — Frequency of the power supply in Hz
• \( p \) — Number of poles in the motor (always an even number)

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

3. Importance of Synchronous Speed

Details: Knowing the synchronous speed is essential for motor selection, speed control applications, and understanding motor performance characteristics.

4. Using the Calculator

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

5. Frequently Asked Questions (FAQ)

Q1: Why is the number of poles always even?
A: Synchronous motors require pairs of north and south poles, so the number of poles is always an even number (2, 4, 6, etc.).

Q2: What's the difference between synchronous and actual motor speed?
A: In synchronous motors, the rotor turns at exactly the synchronous speed. In induction motors, there's a slight difference called "slip."

Q3: What are typical synchronous speeds?
A: For a 60Hz system: 3600 RPM (2-pole), 1800 RPM (4-pole), 1200 RPM (6-pole). For 50Hz: 3000 RPM, 1500 RPM, 1000 RPM respectively.

Q4: Can synchronous speed be changed?
A: Yes, by changing either the frequency (using a variable frequency drive) or the number of poles (though this requires physical motor modification).

Q5: Why is the constant 120 used in the formula?
A: The 120 comes from converting seconds to minutes (60) and accounting for the fact that each pair of poles produces one complete cycle (×2).