Understanding the commutator

                                                                                         

The commutator is a term that is widely applied in the fields of electronics and mathematics. In the literal sense, it means an electrical switch that periodically and consistently reverses the flow of electric current in a motor or a generator. While in mathematics, the commutator is used to indicate the extent of failure in binary operations. In electronics, a commutator is commonly seen in rotating devices that use direct current. When the direction of the flow of electricity is reversed, a steady torque is produced that is then used to rotate the armature. The pattern is preset and it balances the flow of electricity in the circuit.

What it is

A typical commutator consists of a set of copper segments that are set around the outer part (circumference) of the rotating part of a rotor. Carbon made spring loaded brushes are fixed to the stationary part and these brushes carry electric current to the motor or away from it as in a generator. Each of the segments is separated from the rest by means of an insulated covering. Mica was used in the early days however; extensive research into the field of polymers has led to the usage of plastic spacers. In smaller equipments, the commutator fragments can be made of sheet metal however, in larger machines, copper casting is used.

Pros and Cons

Wear and tear caused due to friction amidst the brushes and the segments has been one of the major issues plaguing commutator devices since the early days. Carbon brushes which suffer greater wear and tear are designed in such a way that they can be replaced easily without dismantling the machine. Copper brushes (commonly used in older devices) on the other hand, cause the commutator more damage. Hence in smaller devices, the motor is simply discarded when rendered useless.

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