|Electrical Machines - Basic vocational knowledge (Institut für Berufliche Entwicklung, 144 p.)|
|8.3. Three-phase transformer|
Figure 145 - Utilisation of transformer vector groups in power supplies
1 Power station generator, 2 Machine transformer, 3 Network transformer, 4 Distribution transformer, 5 Substation transformer
Block and machine transformers
- Block transformers along with a generator make up one unit. They establish the connection between the generator and the high-voltage side.
- Machine transformers operate in the same manner as block transformers whereby, initially, several generators work together on a bus bar.
- Preferred vector group for both transformers is Yd5.
- Mains transformers function as a link between transmission networks of differing voltage planes, e.g. between the 380 kV and 220 kV mains.
- Network transformers are preferred in the Yy0 vector group.
Distribution and urban network transformers
- Distribution transformers link the transmission network to the consumer system.
- Urban network transformers are transformers whose undervoltage is less than 1 kV. Particular significance accrues to supplying the asymmetrically loaded urban network.
- The vector group Dy5 is suitable for urban network and distribution transformers.