In actual operation, rotor speed always lags the magnetic field’s speed, allowing the rotor bars to cut magnetic lines of force and produce useful torque. This speed difference is called slip speed. Slip also increases with load and it is necessary for producing of torque.
Why is slip important in an induction motor?
The difference between the synchronous speed of the electric motor magnetic field, and the shaft rotating speed is slip – measured in RPM or frequency. Slip increases with increasing load – providing a greater torque.
What happens if the slip of induction motor is one?
Slip = 1, means that rotor is stationary. Negative value of slip in induction motor can be achieved when the rotor speed is more than the synchronously rotating magnetic flux.
Under what condition the slip in an induction motor is greater than one?
So if the magnetic flux is revolving in the direction of clockwise, then the rotor will turn rotating in the anti-clockwise direction. So, the speed among them will be like (Ns + Nr). In braking or Plugging of this motor, the slip is greater than ‘1’ is attained to rapidly bring the rotor of the motor at rest.
What is normal slip of an induction motor?
Because of this speed difference, the motor rotates at a speed slightly slower than the synchronous speed. Slip is normally expressed in percentage. Slip of a power induction motor is 2 to 3% when the motor is operated under the rated load.
What is cogging and crawling in induction motor?
A.Cogging can also be reduced by using skewed rotor. Q.What is Crawling? A: It has been observed that squirrel cage type induction motor has a tendency to run at very low speed compared to its synchronous speed, this phenomenon is known as crawling. The resultant speed is nearly 1/7th of its synchronous speed.
What is Torque slip?
The torque slip curve for an induction motor gives us the information about the variation of torque with the slip. The slip is defined as the ratio of difference of synchronous speed and actual rotor speed to the synchronous speed of the machine.
What is slip speed of induction motor?
The speed at which the induction motor work is known as the slip speed. The difference between the synchronous speed and the actual speed of the rotor is known as the slip speed. In other words, the slip speed shows the relative speed of the rotor concerning the speed of the field.
How is motor rating slip calculated?
The multiplication of 100 and speed difference divided by the synchronous speed is known as slip of an induction motor. It’s always represented in percentage, generally it ranges from 0.4% to 6% based on its design factors.
What does negative slip mean?
If slip is negative, the “input power” to the electrical terminals will be negative, implying that power is flowing out of the electrical terminals.
What is synchronous speed?
Synchronous speed is a significant parameter for the rotating magnetic field-type AC motor. It is determined by the frequency and the number of magnetic poles. Synchronous speed No = [rps, revolutions per second] f = Frequency [Hz]
What type of rotor is most commonly used in an induction motor?
How does an induction motor start?
When the supply is connected to the stator of a three-phase induction motor, a rotating magnetic field is produced, and the rotor starts rotating and the induction motor starts. … At the time of starting, the motor slip is unity, and the starting current is very large.
What are the applications of induction motor?
AC induction motors are the most common electric motors in the world. These simple, reliable and economical motors are found in refrigerators, washing machines and furnaces, as well as conveyors, pumps, winders, wind tunnels and other industrial equipment.