1. Design of Three Phase Transformer

2. Contents Types of transformers Position of HV & LV windings
Core & Yoke cross-sectional area
Importance of mitered joints
Different types of transformers windings
Different methods for cooling of transformers

3. Types of transformers Power transformers Distribution transformers
Step-up transformers
Step-down transformers
Core type transformers
Shell type transformers
Single phase transformers
Three phase transformers

4. Position of HV & LV windings

5. Core & Yoke cross-sectional area

7. Importance of Mitred joints
The Iron loss and the no load current can be decreased if the flux lines are made to flow along the direction of the grain orientation. This is possible in mitred (bevelled) joints are used for cores and yoke as shown in figure.

8. Different types of transformers windings
Cylindrical windings
Helical windings
Double helical windings
Multi-layer helical windings
Cross-over windings
Disc & continuous disc windings
Aluminum windings

9. Different methods for cooling of transformers
Medium => Air => Gas => Synthetic oil => Mineral oil => Solid insulation => Water
Circulation => Natural => Forced

10. Cooling method for DRY type x’mer 1) Air natural (AN) 2) Air Blast (AB)
Cooling methods for Oil immersed x’mer 1) Oil Natural (ON) 2) Oil Natural Air Forced (ONAF) 3) Oil Natural Water Forced (ONWF) 4) Forced Circulation of Oil (OF) i) Oil Forced Air Natural (OAFN) ii) Oil Forced Air Forced (OFAF) iii) Oil Forced Water Forced (OFWF)