How To Working Of D.C. Generator

Working Of D.C. Generator

A single conductor loop ABCD is placed between two field poles N (North) and S (South). The conductor ab is connected to x and c, d to y segments of the commutator as shown in figure 10.

If the loop is rotated in an anticlockwise direction then the direction of induced EMF in conductor abe is from b to the induced current flows towards B to A through the brush A. While in the same time the direction of induced EMF in conductor CD is from d to c. therefore, the potential of brush A remains higher than the of brush B or the brush A is Positive and the brush B is negative.

After half cycle, conductor CD comes near field-pole and the direction of induced EMF, in it is from c to d, while in conductor ab, it is from a to b. In this position, commutator segment x comes in contact with brush A and the segment y with brush B. Even know the direction of current in the external circuit is from B to A. Therefore, the induced EMF is unidirectional, as shown in figure 11(a).

If two coils are used, then 4 commutator segments will be required. the brush a will get positive e.m.f. 4 times in each cycle of rotation, and thus the output available at the brushes A and B will be of the shape, as shown in figure 11 (b). In this way, if more than two coils are used then the resulting EMF will be of nearly ostrich line shape.

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