1 Answer
The RPM (Revolutions Per Minute) of a synchronous motor is determined by the frequency of the supply current and the number of poles of the motor. The formula to calculate the synchronous speed (in RPM) is:
\[
N_s = \frac{120 \times f}{P}
\]
Where:
Explanation:
\[
N_s = \frac{120 \times 60}{4} = 1800 \text{ RPM}
\]
If the supply frequency were 50 Hz, the synchronous speed for a 4-pole motor would be:
\[
N_s = \frac{120 \times 50}{4} = 1500 \text{ RPM}
\]
This means the rotor of the synchronous motor will rotate at exactly 1800 RPM or 1500 RPM, depending on the supply frequency, as long as the motor is running synchronously with the magnetic field.
\[
N_s = \frac{120 \times f}{P}
\]
Where:
- \(N_s\) is the synchronous speed in RPM.
- \(f\) is the supply frequency in hertz (Hz).
- \(P\) is the number of poles of the motor.
Explanation:
- Synchronous speed refers to the speed at which the motor’s magnetic field rotates, and the rotor follows this magnetic field at this speed.
- For example, if the motor is connected to a 60 Hz power supply and has 4 poles, the synchronous speed would be:
\[
N_s = \frac{120 \times 60}{4} = 1800 \text{ RPM}
\]
If the supply frequency were 50 Hz, the synchronous speed for a 4-pole motor would be:
\[
N_s = \frac{120 \times 50}{4} = 1500 \text{ RPM}
\]
This means the rotor of the synchronous motor will rotate at exactly 1800 RPM or 1500 RPM, depending on the supply frequency, as long as the motor is running synchronously with the magnetic field.