Removing The Roadblock: Enhanced arc Flash Safety Using Integrated Primary Vacuum Fault Interruption and Secondary Sensing Systems on Transformers : Copyright Material IEEE Paper No. PCIC-2021-52

Conventional primary fusing alone, while effective for protecting the primary of the transformer, is insufficient in protecting against arc flash dangers. This results in extremely high arc flash values on the secondary of the transformer through the secondary overcurrent protective device. Utilizing a combination of primary vacuum interrupting technology with secondary overcurrent sensing, arc-light sensing, and micro-processor-based relaying, allows secondary fault interruption response time to be significantly reduced, greatly decreasing incident arc energy in some cases by as much as 90%. Integrating this solution into a prefabricated and pretested piece of equipment offers drastically simplified arc flash modeling and equipment installation process, reducing the project timeline and risk of potential errors and complications in the field. Additionally, this technology can be used without the need to activate or engage other protective settings, delivering protection system simplicity and effectiveness to the user with minimal roadblocks or pitfalls. This paper outlines the theory, methodology, and implementation of an integrated transformer arc flash protection system for reducing the incident energy for secondary arcing events, thus, improving the safety of people working in close proximity to medium voltage transformers.