Commutator

A DC motor’s operation is dependent on the interaction of the revolving armature’s magnetic field with the magnetic field of a fixed stator. A force is produced on the armature as the north pole of the armature is attracted to the south pole of the stator (and vice versa). This causes the armature to turn. The commutator is a device linked to the armature that facilitates this switching of current. Commutation is the act of switching the field in the armature windings to provide constant torque in one direction.

Commutation’s main goal is to keep the torque acting on the armature in the same direction at all times. The armature generates alternating voltage, which is converted to direct current via the commutator. Simply put, the commutator controls the direction the electromagnetic fields are pointing by turning the coils on and off. The electricity should always flow “away” on one side of the coil and “towards” on the other.

Commutator

The commutator is an electrical rotating switch that is used in certain types of generators and motors. This is mostly used to reverse the current direction between the external circuit and the rotor. It consists of a cylinder with multiple metal contact segments resting on the machine’s revolving armature. Brushes or electrical contacts are designed sliding contact by consecutive segments of the commutator while it turns, using a carbon press material next to the commutator.

Application

Commutators are used in DC (direct current) devices such as DC generators, many DC motors, and universal motors. The commutator in a DC motor is responsible for supplying electric current to the windings. Torque (constant revolving force) is produced by changing the direction of current within the revolving windings every half turn.

Commutator construction and working

A commutator is made up of a collection of contact bars that are oriented toward the spinning shaft of a DC machine and connected to the armature windings. The commutator reverses the current flow within a winding when the shaft rotates. Once the shaft has completed one-half turn for a given armature winding, the winding will be connected so that current flows through it in the opposite direction.

The armature current causes the set magnetic field to employ a rotational force, rather than a torque, to make the winding circle in a DC motor. In a DC generator, mechanical force can be supplied in the direction of the shaft to keep the armature winding moving by stimulating a current within the winding via the stationary magnetic field. In these two circumstances, the commutators will occasionally reverse the direction of current flow throughout the winding, ensuring that the flow of current within the machine’s circuit remains in just one direction.

Function of commutator in DC Machines

The commutator acts as a reversing switch in DC machines, and its operation in both the motor and the generator is detailed below.

Commutator in DC Machines

In the case of a DC motor, the commutator reverses the flow of current from a DC source at the precise time that the armature’s coil crosses the magnetic unbiased axis. This is necessary to maintain a single-direction torque. As a result, the commutator converts direct current (DC) to alternating current (AC).

The induced e.m.f within the armature coil will affect the nature of the commutator in a DC generator. As a result, the current flow in the armature coil will be altered. The commutator will reverse this current precisely when the armature’s coil crosses the magnetic unbiased axis. So, if the load is external to the generator, it will receive a unidirectional current; otherwise, DC will be delivered (direct current).

Slip ring commutator

A slip ring commutator is an electro-mechanical device that allows power and electrical signals to be sent from a stationary to a rotating structure. This can be used in any electromechanical system that requires power transmission while rotating. It can restore mechanical action, simplify system operation, and eliminate cables that are prone to damage hanging from variable joints. A slip ring commutator is a method of connecting electrical components in a revolving assembly. It is, technically, an electric communication device that allows energy to travel between two electrical rotating parts in a motor.

Slip ring commutator construction

The structure of a slip ring commutator comprises immovable graphite, also known as metal contact, which wipes on the outside diameter of a spinning metal ring.

The flow of electric current or signal is accomplished through the stationary brush toward the metal ring for forming the connection when the metal ring twists. If more than one electrical circuit is necessary, an extra ring or brush gathering is stacked together with the revolving axis.

Conclusion

The page contains all of the critical information that a student needs to know about the commutator at the basic level, such as its application, working, function, among other things. This is a vital piece of equipment for most of the electric generators and motors. It consists of a cylinder made up of several metal contact segments.