Slip is a specific performance parameter of an asynchronous motor. The current and electromotive force of the rotor part of the asynchronous motor are generated due to the induction with the stator, so the asynchronous motor is also called an induction motor.
To evaluate the speed of an asynchronous motor, it is necessary to introduce the slip of the motor. The difference between the actual speed of the motor and the synchronous speed of the magnetic field, that is, the slip, determines the change of the motor speed.
For different series of motors, due to the particularity of the actual application, or the tendency to achieve certain performance requirements of the motor, it will be realized through the adjustment of the slip ratio. For the same motor, the slip of the motor is different in different specific states.
During the motor starting process, the motor speed is a speed-up process from static to rated speed, and the motor slip is also a change process from large to small. At the moment of starting the motor, that is, the specific point at which the motor applies voltage but the rotor has not yet moved, the slip rate of the motor is 1, the speed is 0, and the induced electromotive force and induced current of the rotor part of the motor are the largest, which is reflected in the appearance of the stator part of the motor The starting current of the motor is particularly large. As the motor changes from stationary to rated speed, the slip becomes smaller as the speed increases, and when the rated speed is reached, the slip is in a stable state.
In the no-load state of the motor, the resistance of the motor is very small, and the speed of the motor is basically equal to the value calculated according to the ideal slip, but it is always impossible to reach the synchronous speed of the motor. The slip corresponding to no-load is basically about 5/1000 .
When the motor is in the rated operating state, that is, when the motor applies the rated voltage and drags the rated load, the motor speed corresponds to the rated speed. As long as the load does not change much, the rated speed is a stable value lower than the speed of the no-load state. At this time, the corresponding The slip rate is around 5%.
In the actual application process of the motor, starting, no-load and load operation are three specific states, especially for asynchronous motors, the starting state control is particularly important; during the operation, if there is an overload problem, it is intuitively manifested as the motor winding At the same time, according to the different degrees of overload, the speed of the motor and the actual voltage of the motor will also change.
Post time: Mar-29-2023