# Eletrobras Furnas Commissions 500 kV Eco-Friendly Digital Substation at Serra da Mesa

> Brazilian utility giant Eletrobras Furnas has energized a state-of-the-art 500 kV digital substation expansion at the Serra da Mesa hydroelectric hub in Goiás, featuring vegetable ester-immersed shunt reactors, non-SF6 vacuum breakers, and a full optical Process Bus network complying with IEC 61850-9-2.

- **Publish Date:** 2026-09-26
- **Category:** transmission-substations
- **Reading Time:** 5 min
- **Original Source Citation:** [Eletrobras Furnas & ONS Brasil](https://www.eletrobras.com/pt/furnas/noticias/subestacao-digital-500kv-serra-da-mesa-inauguracao)
- **Tags:** Eletrobras, Furnas, 500 kV Substation, Digital Substation, IEC 61850, Vegetable Ester, Shunt Reactor, Brazil, ONS
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## Modernizing Brazil’s Central Hydro and Solar Transmission Crossroads

The Serra da Mesa complex in central Brazil serves as a crucial power transmission nexus, interconnecting the North-South transmission intertie with central industrial load centers. To accommodate surging gigawatt-scale solar generation in Goiás and Minas Gerais, Eletrobras executed a comprehensive high-voltage digital modernization.

The project replaces legacy electro-mechanical switchyards with an advanced digital substation topology that eliminates over 80% of copper control cabling, replacing it with resilient redundant fiber-optic rings operating under the High-availability Seamless Redundancy (HSR) protocol.

## Vegetable Ester Shunt Reactors and Vacuum Interrupters

Setting an environmental precedent for tropical grid infrastructure, the newly installed 500 kV 100 Mvar variable shunt reactors (VSR) are filled with natural vegetable-based ester dielectric fluids derived from sustainable crops. Natural ester fluids offer a fire point above 315°C and complete biodegradability, protecting surrounding river ecosystems.

The 500 kV switchgear incorporates high-voltage vacuum circuit breakers utilizing clean dry air insulation, eliminating greenhouse gas SF6 emissions across the facility.

## Real-Time Synchronized Phasor Teleprotection

Optical instrument transformers (OCTs/OVTs) measure current and voltage waveforms with microsecond timestamping, transmitting Sampled Values directly to digital protection relays.

National Grid Operator ONS commended the project as a technical blueprint for the Brazilian National Interconnected System (SIN), significantly bolstering transmission reliability across the Cerrado energy corridor.

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