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Because of the above phenomenon, the rotor speed “N” is always less than the synchronous speed “Ns” which keeps the motor moving. This difference between synchronous speed of the rotating magnetic field and synchronous speed is known as slip. Hence slip is an essential feature for proper working of the induction motor.
What is the importance of slip?
What is the importance of slip? Slip plays an important role in the operation of the induction motor. The torque produced by the induction motor is directly proportional to induction motor slip. At no-load induction motor requires small torque to meet with the frictional, iron and other losses, therefore slip is small.
Why is slip necessary in an induction motor?
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 does a slip occur in the three phase induction motor?
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 full load slip?
At full load the speed of the motor is 1350 rpm. Hence slip at full load = 5.33% When the motor is so loaded that the rotor speed is reduced to 0, the value of Slip is 1. Hence, value of Slip gradually increases from no-load to full load.
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 slip in AC 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. Slip is required to produce torque.
What is percentage slip and 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.
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.
How is slip speed calculated?
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 do you mean by negative slip and when it occurs?
Negative slip will occur when suction pipe is long, delivery pipe is short and pump is running at high speed.
What happens when slip of 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. At synchronous speed,slip is zero and hence torque developed by the motor is zero.
Which type of motor is mostly used in the industry?
The majority of industrial motors are three-phase AC induction motors due to its reliability and low cost. In this case, the electric current in the stator winding generates a rotating magnetic field that “induces” (hence the name) electric current in the rotor.
What is negative slip?
If the rotor of an induction machine rotates above synchronous speed, slip is negative, as are torque, mechanical output power and air gap power. 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 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 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.
- Cached
| No. of Magnetic Poles | Frequency (Hz) | |
|---|---|---|
| 50 | 60 | |
| 16 | 375 | 450 |
| 20 | 300 | 360 |
What is positive slip?
A positive slip indicates that the wheels are spinning; negative slip indicates that they are skidding. Locked brakes, , means that and sliding without rotating.
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 is synchronous speed and slip?
Slip is the difference between the synchronous speed of a motor and its actual speed. Mathematically it is determined by. Slip = Synchronous Speed − Actual Speed. Using the example above for synchronous speed of a motor with four poles operating at 60 hertz, the value was calculated to be 1800 RPM.
What will happen when the slip is 100 and zero?
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 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 no load slip?
At no-load condition, the rotor speed is almost equal to the synchronous speed. e.g A 4 pole, 60 Hz induction motor at no load turning at ηr = 1790 RPM will have slip = (1800 – 1790)/(1800) = 0.55% Where 1800 is the synchronous speed of 4 pole, 60 Hz induction motor.
