Anatomy of a Complex Electrical Failure and its Forensics Analysis

• Published in: IEEE transactions on industry applications Vol. 50; no. 4; pp. 2910 - 2918
• Main Authors: Mardegan, Claudio S., Shipp, David D.
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.07.2014; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Anatomy; Capacitance; Catastrophic failure analysis; Failure; Forensic engineering; Joining; Overvoltage; Power transformer insulation; Readers; Surge protectors; Surges; Switches; Transient analysis; Voltage control; transferred surge; surge protection; power system analysis; protection; flashover; switching transient; overvoltage; power system design; grounding monitoring; forensics; Arc flash; transient overvoltage; ungrounded system; grounding
• ISSN: 0093-9994; 1939-9367
• DOI: 10.1109/TIA.2014.2301866

This paper depicts an accident that happened in 2010 in a Brazilian chemical plant. A combination of different events, installations, and commissioning errors coupled with equipment failures involving the primary substation resulted in catastrophic failure. A single-phase failure of a 138-kV disconnect switch, during closing, initiated events and phenomena that resulted in a complete plant shutdown. This paper will walk the reader through the events, forensics analysis, and power system analysis that allowed the authors to identify what happened, how it happened, and what to do to prevent it from happening again. This paper will show how the anatomy of the problem, involving equipment failure, single-phase arcing, switching transients, overvoltage, capacitive coupling, transferred surge voltages, ungrounded system, transient overvoltage due to an arcing ground fault on an ungrounded system, insulation coordination, flashover, and lack of adequate surge protection, all of which resulted in a catastrophic failure of an arc resistant switchgear and a potentially serious arc flash incident. The research followed some steps that will be commented on here as well as the lessons learned.