Thanks to the Smart Grid initiative, the focus for medium-voltage MV (13.8–34 kV) smart meters leveraged the development of sensors for distribution application. In order to be useful at power quality monitoring, the sensors needs to attend, at least, the International Electrotechnical Commission (IEC) 61000–4-30 and IEC 61000–4-7 standards with high-accuracy in terms of voltage (less than 0.1%), current (less than 1.0%) and measuring the waveform distortion data up to the 50th harmonic of 50 or 60 Hz alternating frequency. This kind of sensor is built with two capacitors connected in series. The first capacitor is a commercial electronic low-voltage device. One terminal of this capacitor is connected to the medium-voltage (MV) conductor. The second one, is connected to the other capacitor that is constructed using the own sensor packaging. This second capacitor has an electrode, that is connected with the first capacitor and the other terminal is connected to the ground. The voltage is measured between the terminals of the low voltage capacitor. The performance of this capacitor depends on the geometry and the materials used in the electrical insulation. This chapter describes the simulations and modeling of the capacitor electrodes using a finite-elements software, COMSOL Multiphysics, for modeling in order to optimize the performance of sensor in terms of electric field distribution.