Page 68 - Electrical Equipment Handbook _ Troubleshooting and Maintenance

TRANSFORMERS

TRANSFORMERS 3.25

1. Wye-wye (Y-Y)
2. Wye-delta (Y- )
3. Delta-wye ( -Y)
4. Delta-delta ( - )
Figure 3.22 illustrates a Y-Y connection.

TRANSFORMER RATINGS

Transformers have ratings for apparent power, voltage, current, and frequency.

Voltage and Frequency Ratings of a Transformer
The voltage rating of a transformer is used to protect the winding insulation from fail-
ure due to high voltage applied to it. It also has a second purpose associated with the

FIGURE 3.22 Three-phase transformer Y-Y connections and wiring diagram.

Downloaded from Digital Engineering Library @ McGraw-Hill (www.digitalengineeringlibrary.com)
Copyright © 2004 The McGraw-Hill Companies. All rights reserved.
Any use is subject to the Terms of Use as given at the website.