Hello friends, in this article we will know how many types of rotors are there? What is a Rotor? And you will know about many facts related to it.
rotor | rotor
shaft mounted rotor laminated It is a core which has slots on its outer periphery. The windings placed in these slots (called rotor windings) may be of one of the following two types:
- squirrel cage rotor
- wound rotor
Squirrel Cage Rotor | squirrel case rotor
It consists of a laminated cylindrical core with parallel slots on its outer circumference. A copper or aluminum bar is placed in each slot. All these rods are attached at each end to metal rings called end rings (see Fig. 20.2). This forms a permanently short-circuited winding that is indestructible.
The entire construction (bars and end rings) resembles a squirrel cage and hence the name. The rotor is not electrically connected to the supply, but to the stator. transformer Inspired by action. Induction motors that employ a squirrel cage rotor are called squirrel cage induction motors.
Most 3-phase induction motors use a squirrel cage rotor because it has a remarkably simple and robust construction that enables it to operate in the most adverse conditions. However, it suffers from the disadvantage of low starting torque. This is because the rotor bars are permanently short-circuited and for large starting torques it is not possible to add any external resistance to the rotor circuit.
Wound Rotor | Wound Rotor
It consists of a laminated cylindrical core and a 3-phase winding similar to the one on the stator (see Fig. 20.3). The rotor windings are evenly distributed in the slots and are usually star-connected.
The open ends of the rotor windings are brought out and connected to three insulated slip rings mounted on the rotor shaft, with a brush hinge on each slip ring. The three brushes are connected by a 3-phase star-connected rheostat. Initially, external resistors are included in the rotor circuit to give a large starting torque.
As the motor moves up to speed, these resistance fractions gradually drop to zero. External resistors are used only during the starting period. When the motor attains normal speed, the three brushes are short-circuited so that the wound rotor continues like a squirrel cage rotor.
Read in Hindi: What is a rotor? , What is the rotor?