Eliminating the Fifth Harmonic Component in a Three-Phase AC Generator

Introduction:
In a three-phase AC generator, the induced voltage waveform consists of multiple harmonic components. The fifth harmonic component is one of these components, and under certain circumstances, it may need to be eliminated. This can be achieved by using a specific winding pitch.

Understanding Harmonics:
Harmonics are sinusoidal components with frequencies that are integer multiples of the fundamental frequency. In the case of a three-phase AC generator, the fundamental frequency is the frequency of the power supply (typically 50 or 60 Hz). The fifth harmonic component has a frequency five times higher than the fundamental frequency.

Winding Pitch:
The winding pitch refers to the distance between consecutive coil sides in a winding. It is determined by the number of slots and poles in the generator. The winding pitch plays a crucial role in the distribution of harmonic components in the induced voltage waveform.

Eliminating the Fifth Harmonic Component:
To eliminate the fifth harmonic component, a specific winding pitch can be used. Option 'B' states that the required winding pitch is 4/5.

Explanation:
When the winding pitch is set to 4/5, the induced voltages in the generator's windings cancel out the fifth harmonic component. This cancellation occurs because the winding pitch of 4/5 ensures that the voltages induced in adjacent poles have a phase difference of 144 degrees.

Reasoning:
The fifth harmonic component can be eliminated by ensuring that the voltages induced in adjacent poles have a phase difference of 144 degrees. By using a winding pitch of 4/5, this phase difference is achieved, resulting in the cancellation of the fifth harmonic component.

Conclusion:
In conclusion, the fifth harmonic component of the induced voltage in a three-phase AC generator can be eliminated by using a winding pitch of 4/5. This specific winding pitch ensures that the voltages induced in adjacent poles have a phase difference of 144 degrees, leading to the cancellation of the fifth harmonic component.