Table of Contents
The slip of an Induction motor can never be zero. This is because 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.
Why the slip of induction motor is never zero b What happens if the slip of induction motor is one c What is the value of the slip for an induction motor at no load and full load?
This is the reason; slip is never zero in an induction motor. 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.
What happens if a slip is between 0?
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 happens if slip of induction motor is 1?
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 slip formula?
Formula to find slip = (ns – n) x 100/ns. substitute the values in the above formulas. speed difference = 1500 – 1450. = 50. slip = 50/1500 x 100.
What does negative slip mean?
Negative slip indicates that the motor is running above synchronous speed. This can happen only when it is driven by a prime mover. This motor becomes an induction generator.
What is the value of slip at stand still?
When the motor is at standstill, the relative speed of the rotating magnetic field and the rotor is equal to 1. The difference in the synchronous speed of the motor and the actual speed of the rotor is unity. In other words, the slip of the motor is unity when the rotor is at standstill.
When can only slip of an induction motor is zero?
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.
How does load affect DC motor?
As the load torque increases the speed of the motor decreases, and assuming the terminal voltage stays constant, the EMF will become lower and thus the armature current will increase. Dec 7, 2014
What is true synchronous mode?
In true synchronous mode, the stator supply frequency is controlled from an independent oscillator. Frequency from its initial to the desired value is changed gradually so that the difference between synchronous speed and rotor speed is always small. This allows rotor speed to track the changes in synchronous speed.
What causes motor slip?
The interaction of currents flowing in the rotor bars and the stators’ rotating magnetic field generate torque. 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.
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 will happen when the slip is 100%?
What will happen when the slip is 100 and zero? As the rotor ends are short circuited current flows through the rotor. So when slip is zero there is no phase difference between stator flux and rotor flux and there is no torque exerted on rotor and rotor does not rotate .
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 a high slip motor?
A high slip motor allows the torque to increase torque per amps even as the motor moves from fixed speed to the locked rotor state. Standard NEMA Design A, B, or C motors operate at one to five percent slip. A NEMA D motor has a high slip of five to thirteen percent.
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 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 are the advantages of synchronous motor?
Advantages of Synchronous Motor
- The advantage of using synchronous motor is the ability to control the power factor.
- Speed remains constant irrespective of the loads in synchronous motors.
- Synchronous motors are built with wider air gaps than induction motors which make them mechanically more stable.
Why there is no slip in synchronous motor?
Because the rotor turns at the same speed as synchronous speed (speed of the rotating magnetic field), there is no slip. The speed of rotation of the motor is constant in a synchronous motor, and does not vary with load, as in an induction motor.
What is the role of slip in induction motor?
In induction motor, slip is important because slip determines torque and also the machine behaviour. Explained as follows: (1) Torque depends on rotor power factor which, in turn, depends on slip. So, torque is lowest when slip(s) is equal to 1 i.e. at standstill.
What is rotor slip?
“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. Slip is required to produce torque.
