How do you prevent an induction motor from crawling?
The primary method of avoiding or minimizing these problems is to select an optimum number of stator and rotor slots and an optimum winding distribution scheme. In addition, it is helpful to select a skew angle for the rotor slots. The shapes of the slots can also be optimized to reduce flux wave distortion.
What is the cause of crawling in induction motor?
The crawling in the induction motor is caused by harmonics developed in motor. Crawling is the tendency of particularly squirrel cage rotor to run at speeds as low as one-seventh of their synchronous speed. This phenomenon is known as the crawling of an induction motor.
What are the disadvantages of slip ring induction motor?
Initial and maintenance cost is more compared to squirrel cage motor because presence of slip rings, brushes, short circuiting devices etc. Speed regulation is poor when operated with external resistances in rotor circuit.
What measure can be taken for minimizing the effect of crawling?
Cogging and crawling are less in slipring induction motor due to it’s high starting torque . In cage rotor motors cogging and crawling can be reduced by proper choice of coil span and skewing (slightly twisting the rotor teeth). By chosing proper combination of stator and rotor slots we can minimize crawling.
What is crawling in machine?
Crawling of Induction Motor It has been observed that squirrel cage type induction motor has a tendency to run at very low speed compared to its synchronous speed, this phenomenon is known as crawling. The resultant speed is nearly 1/7th of its synchronous speed.
What is crawling in induction motor & how it will be reduced?
Crawling of Induction Motor The gap in the motor can be developed with harmonic fluxes because of the magnetic field of the induction motor. The harmonic fluxes in the motor will create an extra torque field. When the synchronous speed of the motor is under 1/7 then crawling can occur.
What is the use of slip rings in slip ring induction motor?
A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure. A slip ring can be used in any electromechanical system that requires rotation while transmitting power or signals.
What is cogging crawling?
because of Cogging motors do not accelerate at all, and crawling induction motors stop accelerating at part speed. Acceleration can also be limited by the torque output of the motor relative to the load torque at that speed. Crawling and Cogging is explain for Induction Motor below.
What is the principle of slip ring induction motor?
This motor runs on the principle of Faraday’s law of electromagnetic induction. When a stator winding is excited with an AC supply, the stator winding produces magnetic flux. Based on faraday’s law of electromagnetic induction, the rotor winding gets induced and generates a current of magnetic flux.