The damper winding (also amortisseur winding) is a squirrel-cage-like winding on the rotor of a typical synchronous

electric machine Electricity is the set of physical phenomena associated with the presence and motion of matter possessing an electric charge. Electricity is related to magnetism, both being part of the phenomenon of electromagnetism, as described by ...

. It is used to dampen the transient oscillations and facilitate the start-up operation. Since the design of a damper winding is similar to that of a

asynchronous motor An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor that produces torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor theref ...

, the winding technically enables the direct-on-line start and can even be used for the motor operation in the asynchronous mode. Originally the damper winding was invented by

Maurice Leblanc Maurice Marie Émile Leblanc (; ; 11 December 1864 – 6 November 1941) was a French novelist and writer of short stories, known primarily as the creator of the fictional gentleman thief and detective Arsène Lupin, often described as a French ...

in France and

Benjamin G. Lamme Benjamin Garver Lamme (January 12, 1864 – July 8, 1924) was an American electrical engineer and chief engineer at Westinghouse, where he was responsible for the design of electrical power machines. Lamme created an efficient induction motor f ...

in the US to deal with the problem of

hunting oscillation Hunting oscillation is a self-oscillation, usually unwanted, about an Mechanical equilibrium, equilibrium. The expression came into use in the 19th century and describes how a system "hunts" for equilibrium. The expression is used to describe phe ...

s due to the early generators being driven by the directly connected

steam engine A steam engine is a heat engine that performs Work (physics), mechanical work using steam as its working fluid. The steam engine uses the force produced by steam pressure to push a piston back and forth inside a Cylinder (locomotive), cyl ...

s with their pulsating

torque In physics and mechanics, torque is the rotational analogue of linear force. It is also referred to as the moment of force (also abbreviated to moment). The symbol for torque is typically \boldsymbol\tau, the lowercase Greek letter ''tau''. Wh ...

. In the modern designs the generators are driven by

turbine A turbine ( or ) (from the Greek , ''tyrbē'', or Latin ''turbo'', meaning vortex) is a rotary mechanical device that extracts energy from a fluid flow and converts it into useful work. The work produced can be used for generating electrical ...

s and the issue of hunting is less important, although pulsating torque is still encountered by motors, for example, while driving the piston compressors. The construction of the damper windings is complex and largely based on

empirical knowledge Empirical evidence is evidence obtained through sense experience or experimental procedure. It is of central importance to the sciences and plays a role in various other fields, like epistemology and law. There is no general agreement on how the ...

. A typical damper winding consists of short-circuit bars that in the machines with

cylindrical rotor 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 ...

s share the slots with the

field winding A field coil is an electromagnet used to generate a magnetic field in an electro-magnetic machine, typically a rotating electrical machine such as a motor or generator. It consists of a coil of wire through which the field current flows. In a ...

s, and in the case of salient pole rotors are located in the dedicated slots on the surfaces of

pole shoe 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 ...

s. There are no bars in the quadrature axis area of the salient pole machines. The bars are terminated on rings or plates encircling the rotor.

References

Sources

* * * Electrical engineering Electromagnetic coils {{improve categories, date=July 2023