ECEN 459 Lab #4 Background Transformers are passive devices which exist primarily to increase or decrease voltage in order to facilitate the distribution of power in a grid. As the name entails, step-up transformers increase the voltage, while step-down transformers decrease the voltage. Transformers that are deployed in the grid are provided a set of rated values, which can be measured physically. However, using an equivalent circuit model seen in Figure 1 and simulations, they may also be calculated. Both approaches use what are known as open-circuit and short-circuit tests