Example Problems with Transformers

Problems 1-3

Kevin Starkey, Nick Christman, Aric Vyhmeister

Problem 1. An ideal step down transformer has a winding of $N_{1}=10{\text{ turns and }}N_{2}=2$ turns. If the input voltage is 1200V, what is the resulting output voltage?

Figure 1: Model for an ideal transformer.

Figure 2: Magnetic circuit of an ideal transformer.

Solution

By modifying equation 5-39 (Mohan 5-22) we can obtain an equation for the output voltage. That is,

$e_{2}=\left({\frac {N_{2}}{N_{1}}}\right)e_{1}$.

With the information provided we can now determine the output voltage:

$e_{2}=\left({\frac {N_{2}}{N_{1}}}\right)e_{1}=\left({\frac {2}{10}}\right)1200V=240V$