The electrical submersible pump (ESP) system is intended to lift large volumes of fluids in an efficient and cost-effective manner. Several variables in the lifting process affect the production level. The variable speed drive (VSD) enables the operator to control performance of the ESP system, changing the speed of the motor installed at the bottom of the well, by making changes in the frequency. Fluid production at the surface is affected to a large extent by the motor operation. Motors installed at the bottom may generate a maximum torque depending on the voltage applied to their terminals at a given frequency. Due to the differences in fluid properties, it is necessary to vary the motor speed in order to obtain the maximum torque; this is achieved by modifying the voltage applied at the motor terminals. This is one of the reasons for using VSD in ESP systems. Typically, VSD output voltages are lower than those required by the ESP system motor for optimal operation. In addition, since the VSD operating frequency varies depending on the well characteristics and, given that the VSD wave contains harmonics, use of a conventional transformer is not possible in these cases. For these reasons, a special step-up transformer must be used.