ISA Energia Brasil S.A., also known as ISA CTEEP, is Brazil's leading private electricity transmission company. Founded in 1999 and based in São Paulo, it operates as a subsidiary of the multi-Latin American group ISA. The company plays a vital role in the energy transition by connecting renewable energy sources, such as wind, solar, and hydropower, to major consumption centers across Brazil. ISA Energia Brasil manages an extensive infrastructure that includes approximately 23,000 km of transmission lines and 137 substations, handling about 30% of Brazil's National Interconnected System electricity transmission. The company operates in 18 states and employs around 1,600 people. It is committed to network maintenance, modernization, and expansion, having successfully won 19 transmission auction lots since 2016. The company's activities are coordinated by the National Electricity System Operator and regulated by the National Electricity Agency.