Frequency of Rotor Current in a 50 Hz 3 Phase Induction Motor

Introduction:
A 3-phase induction motor is an asynchronous motor that operates on the principle of induction. The stator winding produces a magnetic field that rotates at synchronous speed. The rotor winding is short-circuited and the magnetic field induces a current in the rotor. This current produces a magnetic field that interacts with the stator field and produces torque.

Frequency of Rotor Current:
The frequency of the rotor current in a 3-phase induction motor is not the same as the frequency of the supply voltage. The rotor current frequency is affected by the slip of the motor. Slip is the difference between the synchronous speed and the actual speed of the rotor. The rotor frequency can be calculated using the following formula:

fr = (s x fs) / p

Where,
fr = rotor frequency
s = slip
fs = supply frequency (50 Hz in this case)
p = number of poles

Answer:
In a 50 Hz 3 phase induction motor, the frequency of the rotor current is about 2 Hz. This is because the slip of the motor is typically between 2% to 5%. For example, if the motor has a slip of 3%, then the rotor frequency would be:

fr = (0.03 x 50) / 2 = 0.75 Hz

However, it is important to note that the frequency of the rotor current is not constant and varies with the load on the motor. As the load increases, the slip also increases, which results in a decrease in the rotor frequency.