Online Insulation Monitoring of Low-Voltage Unearthed Distribution Systems

摘要

This paper deals with the implementation of online insulation monitoring of low-voltage unearthed distribution systems. The purpose of choosing and applying unearthed distribution systems is the various advantages it possesses in the industrial safety area such as continuity of service and prevention from risk of fire and shock. It is an important task to detect insulation fault in the energized (online) system without affecting the distribution system. The main purpose is to deal with the insulation fault in the energized system and maintain the continuity of the system supply. The idea is to continuously monitor the low-voltage distribution system and detect the insulation/ohmic faults in the ungrounded energized low-voltage distribution system using an insulation monitoring device (IMD). Basically, 'online' suggests real-time measurement and 'insulation monitoring' is the continuous insulation monitoring and leakage fault detection of ungrounded distribution systems. The IMD detects insulation faults between the energized system and earth. An external injection, generated by the IMD, is made in the distribution system to monitor the system. During the healthy condition of the distribution system, the IMD reads and displays high insulation values. When an insulation fault occurs, the IMD reading drops down to the corresponding value of insulation fault, which is proportional to the voltage. Evaluation of various studies has been made, and various cases have been studied and implemented using Multisim software. Based on these case studies, testing of the hardware and hardware implementation of one of the case studies has been showcased.