What is the role of commutator in DC generator?

A brush is a device which conducts current between stationary wires and moving parts, most commonly in a rotating shaft. Typical applications include electric motors, alternators and electric generators.

In DC machines the air gap length changes between the slot and teeth of the armature when the armature is rotating under constant magnetic field. So in order to avoid this vibration effect armature teeth is skewed.

If you reverse the wire polarities so that each wire is connected to the opposing power supply terminal, then the motor rotates counter clockwise. DC Motor rotation does have to do with the voltage polarity and the direction of the current flow.

When the armature of a d.c. motor rotates under the influence of the driving torque, the armature conductors move through the magnetic field and hence e.m.f. is induced in them as in a generator. The induced e.m.f. acts in opposite direction to the applied voltage V (Lenz’s law) and in known as back or counter e.m.f.

Commutation is defined as giving up part or all of the pension payable from retirement in exchange for an immediate lump sum. Commutation factors (usually calculated by the Scheme Actuary) are used to determine the amount of pension which needs to be given up in order to provide the lump sum.

Forced Commutation : The process of turning OFF a thyristor or SCR by using external circuits is known as Forced Commutation. The circuit used for this commutation method is known as commutation circuit and the components that are used in the circuitry , are known as commutating components.

the act of substituting one thing for another; substitution; exchange. the changing of a prison sentence or other penalty to another less severe. the act of commuting, as to and from a place of work.

Function of commutator: To keep the torque on a DC motor from reversing every time the coil moves through the plane perpendicular to the magnetic field, a split-ring device called a commutator is used to reverse the current at that point.

A commutator is a specialized slip ring typically used on Direct Current motors and electrical generators to transfer electrical power between the stationary housing and the rotating armature with the added purpose of reversing the electrical current direction.

A commutator in quantum mechanics tells us if we can measure two ‘observables’ at the same time. If the commutator of two ‘observables’ is zero, then they CAN be measured at the same time, otherwise there exists an uncertainty relation between the two.

How does a DC Motor work? The DC motor is a machine that transforms electric energy into mechanical energy in form of rotation. Its movement is produced by the physical behavior of electromagnetism. DC motors have inductors inside, which produce the magnetic field used to generate movement.

The armature winding is the main current-carrying winding in which the electromotive force or counter-emf of rotation is induced. The current in the armature winding is known as the armature current. The armature windings of dc motors are located on the rotor, since they must operate in union with the commutator.

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.

So the current in the coil becomes opposite. Thus the forces again reverse which makes the coil to continue it’s rotation along a single direction. So the commutator reverses the current in every half turn producing a steady torque and the armature coil rotates in a single direction.

An armature generally refers to one of the two principal electrical components of an electromechanical or electrical machine — generally in a motor or generator — but it may also mean the pole piece of a permanent magnet or electromagnet, or the moving iron part of a solenoid or relay.

Field magnet refers to a magnet used to produce a magnetic field in a device. It may be a permanent magnet or an electromagnet. When the field magnet is an electromagnet, it is referred to as a field coil.

In a DC machine, the main field is produced by field coils. In both the generating and motoring modes, the armature carries current and a magnetic field is established, which is called the armature flux. The effect of armature flux on the main field is called the armature reaction.

Thus, a reverse voltage will appear across the device simultaneously, which will turn off the thyristor immediately. This process is called as natural commutation as thyristor is turned off naturally without using any external components or circuit or supply for commutation purpose.

In a DC motor, the magnet (and its magnetic field) is fixed in place and forms the outside, static part of the motor (the stator), while a coil of wire carrying the electric current forms the rotating part of the motor (the rotor).