Explain the purpose of tertiary winding in transformers. How does the winding minimize 3rd orderharmonics?

The purpose of the tertiary winding in transformers is to provide a third voltage level, to supply for auxiliary loads, or to serve as a delta connected stabilizing winding in a wye-delta connected transformer.

In terms of minimizing 3rd order harmonics, the tertiary winding, which is usually delta-connected, provides a path for the zero sequence currents and the third harmonic components.

Here's a step-by-step explanation:

1. Harmonics in power systems are generated due to the operation of non-linear loads like transformers, electric machines, and power electronic converters.

2. The third harmonic is a type of non-triple harmonic, which means it cannot circulate in the delta winding of the transformer.

3. However, the tertiary winding, which is delta-connected, provides a closed path for these harmonic currents.

4. This allows the third harmonic currents to circulate within this winding, preventing them from flowing into the power system.

5. As a result, the tertiary winding helps in reducing the distortion of the sinusoidal waveform of the power system caused by these harmonics.

6. This not only improves the power quality but also enhances the efficiency and lifespan of the power system equipment.

In conclusion, the tertiary winding in transformers plays a crucial role in providing an additional voltage level and mitigating the effects of third harmonic currents.