Direct Current (D.C.) Generator

A direct current is one that current always flows in one direction even though it may vary in value

A direct current is obtained by connecting a split ring known as a commutator to an external resistance or load. The two ends of the coil are attached to the commutator, which balances the charges to and from the generator, thus resulting in a current that does not alter direction.

As the coil rotates, the two halves of the commutator also rotate. The speed of rotation is the same for the coil and the commutator.

Each of the two halves of the commutator connects to a brush that connects to a different end of the circuit. The brush is stationary and does not rotate.

When the commutator has rotated through half of one complete rotation, the end of the circuit to which each half of the commutator connects changes. This means that the end of the coil to which each half of the circuit connects also changes.

The split ring commutator helps to reverse the connections to the external resistance in every half-turn of the coil so that the current produced flows through the circuit in the same direction.

To Produce Larger E.M.F in Ac or Dc Generators:

1. the armature should have a larger number of turns in the coil
2. the coil should be wound on a soft iron core, to increase magnetic flux through the coil 
3. a strong magnet should be used to produce a strong magnetic field
4. increase the speed of rotation of the coil