On the 3rd of October at 8:55 pm, an explosion followed by fire of grounding transformer caused a short circuit in one of the autotransformers of substation Foz do Iguaçu - 60 Hz. The disturbance resulted in the complete loss of the transformation and the consequent separation of generation in 60 Hz of Itaipu hydroelectric plant of the Brazilian Interconnected Power System - BIPS. There was action of ERAC in the South / Southeast / Midwest and Acre / Rondônia, which resulted in the shutdown of 3,332 MW of load.

Main actions and measures implemented:

• Replacement of the protection relay relating to the scheme against overload of AT04 autotransformer bank, whose poor performance was responsible for the aggravation of the disturbance.
• Restoration of dielectric insulating capacity of the affected area by cleaning and washing of the bay reached by flames and soot.