The rotor is a moving component of an electromagnetic system in the electric motor, electric generator, or alternator. Its rotation is due to the interaction between the windings and magnetic fields which produces a torque around the rotor's axis.
Squirrel-cage rotor
The squirrel-cage rotor consists of laminated steel in the core with evenly spaced bars of copper or aluminum placed axially around the periphery, permanently shorted at the ends by the end rings. This simple and rugged construction makes it the favorite for most applications. The assembly has a twist: the bars are slanted, or skewed, to reduce magnetic hum and slot harmonics and to reduce the tendency of locking. Housed in the stator, the rotor and stator teeth can lock when they are in equal number and the magnets position themselves equally apart, opposing rotation in both directions. Bearings at each end mount the rotor in its housing, with one end of the shaft protruding to allow the attachment of the load. In some motors, there is an extension at the non-driving end for speed sensors or other electronic controls. The generated torque forces motion through the rotor to the load.
Wound rotor
Wound rotor
The rotor is a cylindrical core made of steel lamination with slots to hold the wires for its 3-phase windings which are evenly spaced at 120 electrical degrees apart and connected in a 'Y' configuration. The rotor winding terminals are brought out and attached to the three slips rings with brushes, on the shaft of the rotor. Brushes on the slip rings allow for external three-phase resistors to be connected in series to the rotor windings for providing speed control. The external resistances become a part of the rotor circuit to produce a large torque when starting the motor. As the motor speeds up, the resistances can be reduced to zero.
The rotor is a large magnet with poles constructed of steel lamination projecting out of the rotor’s core. The poles are supplied by direct current or magnetized by permanent magnets. The armature with a three-phase winding is on the stator where voltage is induced. Direct current (DC), from an external exciter or from a diode bridge mounted on the rotor shaft, produces a magnetic field and energizes the rotating field windings and alternating current energizes the armature windings simultaneously.
Non-salient rotor
Non-salient rotor
The cylindrical shaped rotor is made of a solid steel shaft with slots running along the outside length of the cylinder for holding the field windings of the rotor which are laminated copper bars inserted into the slots and is secured by wedges. The slots are insulated from the windings and are held at the end of the rotor by slip rings. An external direct current (DC) source is connected to the concentrically mounted slip rings with brushes running along the rings. The brushes make electrical contact with the rotating slip rings. DC current is also supplied through brushless excitation from a rectifier mounted on the machine shaft that converts alternating current to direct current.
A turbine is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced by a turbine can be used for generating electrical power when combined with a generator. A turbine is a turbomachine with at least one moving part called a rotor assembly, which is a shaft or drum with blades attached. Moving fluid acts on the blades so that they move and impart rotational energy to the rotor. Early turbine examples are windmills and waterwheels.
Gas, steam, and water turbines have a casing around the blades that contains and controls the working fluid. Credit for invention of the steam turbine is given both to Anglo-Irish engineer Sir Charles Parsons (1854–1931) for invention of the reaction turbine, and to Swedish engineer Gustaf de Laval (1845–1913) for invention of the impulse turbine. Modern steam turbines frequently employ both reaction and impulse in the same unit, typically varying the degree of reaction and impulse from the blade root to its periphery. Hero of Alexandria demonstrated the turbine principle in the first century AD and Vitruvius mentioned them around 70 BC.
Gas, steam, and water turbines have a casing around the blades that contains and controls the working fluid. Credit for invention of the steam turbine is given both to Anglo-Irish engineer Sir Charles Parsons (1854–1931) for invention of the reaction turbine, and to Swedish engineer Gustaf de Laval (1845–1913) for invention of the impulse turbine. Modern steam turbines frequently employ both reaction and impulse in the same unit, typically varying the degree of reaction and impulse from the blade root to its periphery. Hero of Alexandria demonstrated the turbine principle in the first century AD and Vitruvius mentioned them around 70 BC.
The word "turbine" was coined in 1822 by the French mining engineer Claude Burdin from the Greek (τύρβη, tyrbē, meaning "vortex" or "whirling", in a memo, "Des turbines hydrauliques ou machines rotatoires à grande vitesse“), which he submitted to the Académie royale des sciences in Paris. Benoit Fourneyron, a former student of Claude Burdin, built the first practical water turbine.
