Improving Design Concepts for Overtemperature System Protection of Transformer Through Analysis of System Events Following an Accident

The project staff investigates and discovers if the output contact of the protection relay fails in an electrical accident. In a short-circuit accident, the protection relay may not issue commands to fix the fault by activating the switch. The investigation result can be used to find the primary cause of the accident and why the equipment was damaged. In replacing the faulty protection relay, all newly installed relays must be tested to verify the functionality of their input and output contacts. Precautionary measures need to be ensured to prevent a similar incident. Poor equipment quality and improper installation cause a newly added power system’s protection relay not to output signals correctly. Despite general procedures of testing the relay’s output and input contacts before integrating the relay into the grid, accidents caused by the abovementioned reasons are still unavoidable. In this study, an in-depth analysis of the data logs and relevant protection relay settings was conducted, focusing on reliability and failure prevention. The analysis result revealed that the protection relay of transformer temperature was set conservatively, failing the backup protection. The case study results and discussions in this study provide a reference for power engineering designers and a guiding framework for accident analysis.