Question: Why There Is Slip In Induction Motor

“Slip” in an AC induction motor is defined as: As the speed of the rotor drops below the stator speed, or synchronous speed, the rotation rate of the magnetic field in the rotor increases, inducing more current in the rotor’s windings and creating more torque.

Does induction motor have slip?

Definition: In Induction Motor, a slip is a speed among the rotary magnetic flux as well as rotor expressed in terms of for every unit synchronous speed. It can be measured in dimensionless & the value of this motor cannot be zero.

Why the slip is never zero in an induction 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 is the 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 the effect of slip on the working of an induction 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.Number of poles, frequencies and synchronous induction motor speed. No. of Magnetic Poles Frequency (Hz) 50 60 20 300 360.

Why do Motors slip?

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.

Can slip be negative?

If the rotor of an induction machine rotates above synchronous speed, slip is negative, as are torque, mechanical output power and air gap power. i.e. the machine is operating as a generator. Rotational losses are 2450W.

When slip is zero rotor will?

If Slip is equal to zero, rotor current is zero and torque is zero. The zero torque means motor will not rotate at all.

What type of motor has a slip factor of 0 %?

In two-pole single-phase motors, the torque goes to zero at 100% slip (zero speed), so these require alterations to the stator such as shaded-poles to provide starting torque. A single phase induction motor requires separate starting circuitry to provide a rotating field to the motor.

What is slip percentage?

The difference between theoretically calculated forward speed based on angular speed of the rim and rolling radius, and actual speed of the vehicle, expressed as a percentage of the latter, is called ‘slip ratio’.

Is 3 phase induction motor is self starting?

Three-phase induction motor is self-starting, because winding displacement is 120 degrees for each phase and supply also has 120 phase shift for 3-phase. It results in a unidirectional rotating magnetic field is developed in air gap which causes 3-phase induction motor to self-start.

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.

What is the importance of slip?

Slip creates a relative speed between the RMF and rotor. That keeps a torque continuously acting on it when the motor is running. So what would happen if slip becomes zero? Bcoz there will be no relative speed between RMF and rotor, and which will stop inducing rotor current.

How can we prevent motor slip?

Slip compensation can be added to AC drives, to reduce the effect of motor slip. A load torque signal is added to the speed controller to increase the output frequency in proportion to the load.

What are the main parts of 3 phase induction motor?

The stator of the three-phase induction motor consists of three main parts : Stator frame, Stator core, Stator winding or field winding.

What is motor slip formula?

Slip speed is the speed difference between the Synchronous speed and Rotor speed. Slip speed = Synchronous speed – Rotor speed = Ns -N. Slip, s = (Ns – N) / Ns.

What does slip power mean?

SLIP-POWER: A PART OF THE AIR-GAP POWER WHICH IS NOT CONVERTED INTO MECHANICAL POWER IS CALLED SLIP POWER. IT IS REPRESENTED BY sPg. where s=slip, Pg= air-gap powerSLIP RECOVERY: THE AIR GAP POWER WHICH IS GETTING WASTED IN ROTOR IS FED BACK TO THE SUPPLY MAINS THIS IS CALLED SLIP RECOVERY.

What is the maximum value of slip?

This is maximum value of slip s possible for induction motor which occurs at start. While s = 0 given us N = Ns which is not possible for an induction motor. So slip of induction motor can not be zero under any circumstances. Practically motor operates in the slip range of 0.01 to 0.05 i.e. 1 % to 5 %.

What is the concept slip?

We know that, an induction motor consists of two assemblies i.e., rotor and stator. 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 the value of slip at synchronous speed?

Synchronous Speed Pairs of Poles Synchronous RPM Slip (RPM) 1 3600 108–180 2 1800 54–90 3 1200 36–60 4 900 27–45.

What is positive slip?

A positive slip indicates that the wheels are spinning; negative slip indicates that they are skidding.

What is meant by 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.