Slip is the differentiation between synchronous and asynchronous speed. … 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.
Why is slip necessary in an induction motor?
If the rotor is spun at synchronous speed there would be zero induction and hence zero torque produced. What you see is slip and that slip creates enough induction which leads to enough torque to overcome residual friction and losses when no proper mechanical load is connected.
What is slip and its significance?
What is the significance of slip? The induction motor is called asynchronous motor because the actual speed of the motor is always less than its synchronous speed. The difference in the actual speed and the synchronous speed is called slip. The torque of the motor depends on the slip.
What happens if the slip of induction motor is one?
When the Value of Slip is >1
If the slip value of the motor is greater than one then the rotor will turn in the opposite direction to the revolution of magnetic flux. So if the magnetic flux is revolving in the direction of clockwise, then the rotor will turn rotating in the anti-clockwise direction.
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 slip in 3 phase induction?
The interaction of currents that is flowing in rotor and stator bars generate a torque. In an actual operation, the rotor speed always lags the magnetic field’s speed, thereby allowing the rotor bars to cut the magnetic lines of force and produce torque. This speed difference is called slip.
What is slip formula?
Formula to find slip = (ns – n) x 100/ns. substitute the values in the above formulas. speed difference = 1500 – 1450. = 50.
What causes slip in a motor?
Slip increases with increasing load – providing a greater torque. It is common to express the slip as the ratio between the shaft rotation speed and the synchronous magnetic field speed. When the rotor is not turning the slip is 100 %.
What does negative slip mean?
A positive slip indicates that the wheels are spinning; negative slip indicates that they are skidding. Locked brakes, , means that and sliding without rotating. Rotation with no velocity, and , means that .
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 is slip torque?
Torque Slip Characteristics of Three Phase Induction Motor. 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 synchronous speed?
: a definite speed for an alternating-current machine that is dependent on the frequency of the supply circuit because the rotating member passes one pair of poles for each alternation of the alternating current.
What happens when slip is zero?
Zero slip means that rotor speed is equal to synchronous speed. If rotor is rotating at synchronous speed in the direction of rotating magnetic field the, there will be no flux cutting action, no emf in the rotor conductors, no current in rotor bar conductor and hence no development of electromagnetic torque.
What is the function of induction motor?
An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor can therefore be made without electrical connections to the rotor.
What is cogging and crawling in induction motor?
Sometimes, squirrel cage induction motors exhibits a tendency to run at very slow speeds (as low as one-seventh of their synchronous speed). This phenomenon is called as crawling of an induction motor. This action is due to the fact that, flux wave produced by a stator winding is not purely sine wave.