Master thesis : State of the art, design and development of a digital leakage current sensor with high sensitivity and fast response

Abstract

In any high voltage installation, leakage currents can lead to losses and damage to power installations. It can also injure or kill people if the current flows through a body. It is thus important to measure and monitor these currents and react accordingly. This thesis report aims to document the conception of a device capable of measuring leakage currents and report the measurements to a master system. This sensor has a high sensitivity, a low error, and a fast response. It works both on AC and DC leakage currents. The sensor embeds an STM32 microcontroller and the communication with the master is done via SPI. This report contains a state-of-the-art review of the leakage current sensing techniques. It also presents a computer modeling of the technique used to choose the configuration and to study the different parameters that might influence the sensitivity. An explanation of the hardware and software designs is given. The experimental validation shows that the device has a decent sensitivity and excellent linearity. However, it was not possible to have both a good differential mode rejection and a good magnetization error rejection at the same time.