Low Voltage Arcing and Fire Testing: Experiments to Compare Arc Flash and Fire Hazard Between Faults Inside LVAC Enclosures and LVDC Enclosures

Abstract

Electrical fires are a significant hazard to the public in both low voltage AC networks and potential hybrid AC DC networks. New Zealand electricity customers are typically linked to an underground LV distribution network using a service fuse located inside an LV enclosure at the boundary between the road and the house. Each year, a small fraction (less than 0.1%) of the pillars on the network may catch fire due to internal component failure, known as a pillar fire. Pillar fires pose a considerable risk to individuals, property, and reputation because of the large number of assets in the fleet and their close proximity to residential and bustling metropolitan areas. Identifying how overheating of connections might result in a fire is essential for managing this risk. The research commences by underlining the importance of fire testing in elevating safety standards and advocates for a stringent safety protocol to safeguard researchers, equipment, and the surrounding infrastructure. It then delves into the procedural steps crucial for executing fire testing experiments, encompassing the development of experimental objectives, methodology, and test plans. The thesis further addresses the setup and calibration of measurement instruments, emphasizing the creation of controlled test environments to ensure precise data collection. Additionally, the report underscores the significance of documentation and data collection, as well as post-experiment analysis and reporting. This thesis's contribution lies in reporting experiments that elucidate the process from hot spots to pillar fires and arc flash events for both LVAC plastic pillars currently in use and the potential response of these pillars in LVDC-operated networks. The experimental setup, dedicated to studying LVAC/LVDC overheating and arc faults, examines the characteristics of AC and DC arc faults at LV levels. The potential data that can be collected aids in a better understanding of fire ignition involving materials associated with plastic LV pillars. The results of these experiments enhance our comprehension of the process leading from overheating connections to pillar fires and arc flash events. Consequently, improvements in equipment specifications and requirements aim to reduce the occurrence of faults due to overheating, thereby mitigating associated risks.