# Eletrobras Furnas Completes 765 kV Transformer Modernization at Foz do Iguaçu Substation for Itaipu Hydropower Delivery

> To guarantee the transmission integrity of 14,000 MW generated by the binational Itaipu Hydroelectric Plant, Eletrobras Furnas has successfully energized five replacement 500 MVA 765/500 kV single-phase autotransformers at Foz do Iguaçu Substation in Paraná, Brazil.

- **Publish Date:** 2026-09-18
- **Category:** transformers-grid
- **Reading Time:** 5 min
- **Original Source Citation:** [Eletrobras Furnas Engineering & Maintenance Board](https://eletrobras.com/en/media/press-releases/foz-do-iguacu-765kv-autotransformer-modernization-completion-september-2026)
- **Tags:** Eletrobras, Furnas, 765 kV, Autotransformers, Itaipu, Brazil, Hydropower
- **Canonical URL:** https://voltformer.com/news/eletrobras-furnas-completes-765kv-foz-do-iguacu-transformer-modernization
- **Markdown Source:** https://voltformer.com/news/eletrobras-furnas-completes-765kv-foz-do-iguacu-transformer-modernization.md

## Replacing 40-Year-Old Extra-High-Voltage Transformers

The Foz do Iguaçu 765 kV Substation is the origin terminal for the massive AC transmission corridors feeding São Paulo and Rio de Janeiro from the Itaipu dam. Original autotransformer banks commissioned in the 1980s were approaching their operational life limits with elevated paper degradation indicators.

The five new 500 MVA single-phase units form a primary 1,500 MVA three-phase bank plus two fast-acting on-site hot spares, featuring modern step-lap core designs that reduce no-load core losses by 22%.

## Advanced Bushing Sensor Integration and Online GIC Monitoring

Because the 765 kV system spans over 900 km of open terrain, the transformers are equipped with real-time geomagnetically induced current (GIC) neutral sensors and continuous capacitive bushing dissipation factor monitors.

Eletrobras completed the complex transport of the 230-tonne units across mountainous terrain without incident, reinforcing the backbone of Brazil’s National Interconnected System (SIN).

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