Working of DC Generator

Working of DC Generator Points : Working of DC Generator As the D.C. supply is given to field winding, which is wound on field poles. This field current is flowing through N turns of winding produces the emf, which sets up the constant magnitude of flux, which flows from N pole to S pole, When the rotor (armature) rotates, (actually generator is not self rotating, but it is coupled with prime-mover) as prime-mover rotates, armature of generator will rotate, the armature winding will cut the flux and according to Faraday’s law of electromagnetic induction, dynamically induced emf will induce in armature winding.

Coil ABCD has N turns rotating in clockwise direction with co rad/sec. The ends of coil joined to two slip ring a and b through brushes 1 and 2. The voltages available at load will be alternating in nature because after every 1800, coil changes their positions so the direction of current will also be changed.

For getting unidirectional (d.c.) voltage, remove two slip ring by one split ring, cut it into two halves and insulate each other by Mica sheet. These two halves are called as commutator. Numbers of commutator segments are equal to number of armature coils.

In first half (0 — 180°) current flows along ABLMCD i.e. brush No. 1 is connected to +ve supply. From (1800 — 360°), direction of current is reversed but at the same instant of time, position of segments a and b have also reversed so again brush No. 1 comes into each with +ve supply and the direction of current through load will be same i.e., L to M.