Forensic Engineering Analysis of an Electrical Substation Fire in a Manufacturing Plant in Brazil

A cable splice failure in one of the cables associated with one of the 6 MVAR capacitor banks in an electrical substation at a manufacturing plant in South America caused a fire in the 88/4.16kV electrical substation. The fire caused the plant to stop production for approximately 29 days while temporary repairs were made. Operating two shifts per day/seven days a week, and stopping for maintenance once a year, the manufacturing production generates approximately $750,000 in revenue per day. The cable splice failure caused an electrical short circuit in the substation 4.16kV distribution system for approximately 120 seconds. The cable splice failure ignited the adjacent cables in the cable tray, causing damage to various sections of the 4.16kV cables, three 88kV disconnect switches, and four 88kV – 4.16kV transformers. The cable fire in the electrical substation resulted in property damages and business interruption losses with an estimated value of $20 million. The four 88kV – 4.16kV transformers that were in service at the time of the substation fire were exposed to voltage transients and electromagnetic forces produced by the short-circuit currents for approximately120 seconds.