The electric induction motor has almost constant speed. Small power induction motors are most often single phase with shorted rotor and need special devices since they do not have their own starting. The three-phase induction motors are of higher power and have their own starting. Since they need a large current of the network, at the moment of starting, special devices are used to decrease it. In series or universal single-phase motors, the rotor winding is brought to https://www.mrosupply.com/motors/dc-motors/2525284_10801400_leeson/ the brushes by interference from a switch, which is a collector made up of blades insulated from one another and connected to the stator.
This type of electric motor works with both direct and alternating current and has variable speed. In the motor to the repulsion the winding of the rotor is taken to the brushes that are connected in short circuit. It has variable speed, being usually used as motor repulsion induction. At start it functions as a repulsion motor that has its own start and then, through a centrifugal device, the slides of the collector are shorted, starting to function as a single-phase induction motor.