Slip, which varies from zero at synchronous speed and 1 when the rotor is stalled, determines the motor’s torque. Since the short-circuited rotor windings have small resistance, even a small slip induces a large current in the rotor and produces significant torque.
Why do induction motors have slip?
Motor Slip is Necessary for Torque Generation
Copper wire coils are wound around these poles. These primary windings are connected to a voltage source to produce a rotating magnetic field.
What is slip in induction motor?
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 there is no slip in synchronous motor?
In motors the number of rotor slots and stator slots are different and thus cogging (magnetic locking) can’t happen. And thus The slip motor can’t run at rated speed. Torque developed by induction motor is proportional to the slip. At synchronous speed,slip is zero and hence torque developed by the motor is zero.
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.
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 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 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 negative slip?
Slip of reciprocating pump: Slip of a pumps defined as the difference between the theoretical discharge and actual discharge of the pump. … Negative slip occurs when delivery pipe is short, suction pipe is long and pump is running at high speed.
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 slip speed?
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.
Why motor starting current is high?
When 3 phase voltage applied across the stator winding for starting of induction motor, high inrush currents magnetize the air gap between the stator and rotor. An induces emf is generated in the rotor windings of the induction motor because of the rotating magnetic field.
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.
Can slip of induction motor be negative?
From the above equation it is clear that, for slip to be negative, the rotor speed should be greater than synchronous speed. Hence,Negative slip is a situation when an induction motor becomes an Hence,Negative slip is a situation when an induction motor becomes an induction generator.
What is motor rated speed?
The rated speed is the speed at which the motor will first produce its maximum designed power output, and “maximum speed,” the fastest the motor can spin while producing that same amount of power./:m] ]The reduction ratio should be applied on the RPM while your load is attached to the motor.