KOLEKTOR ETRA Oil-Immersed Power Transformers

MV / HV Solutions from the SANERGRID Group

KOLEKTOR ETRA oil-immersed power transformers from the SANERGRID Group meet the requirements of the most complex medium- and high-voltage projects in electricity generation, transmission and distribution.

Designed by our Slovenian partner based in Ljubljana for power ratings from 10 to 500 MVA and voltages up to 420 kV, they are intended for grid operators, power producers and industrial clients facing high performance, safety and availability constraints.

The SANERGRID Group supports the entire transformer lifecycle: engineering study, supply, commissioning, industrial risk management and operation, with French-speaking technical support and a comprehensive approach integrating environmental and regulatory requirements.

Present in France for more than 10 years, KOLEKTOR ETRA transformers are installed across the electrical network — from generation to transmission and distribution — serving major public and private stakeholders such as EDF, RTE, ENEDIS, Schneider Electric, Omexom, Bouygues-Equans, CNR, ENGIE and SNCF.

MV / HV Solutions from the SANERGRID Group

KOLEKTOR ETRA oil-immersed power transformers from the SANERGRID Group meet the requirements of the most complex medium- and high-voltage projects in electricity generation, transmission and distribution.

Designed by our Slovenian partner based in Ljubljana for power ratings from 10 to 500 MVA and voltages up to 420 kV, they are intended for grid operators, power producers and industrial clients facing high performance, safety and availability constraints.

The SANERGRID Group supports the entire transformer lifecycle: engineering study, supply, commissioning, industrial risk management and operation, with French-speaking technical support and a comprehensive approach integrating environmental and regulatory requirements.

Present in France for more than 10 years, KOLEKTOR ETRA transformers are installed across the electrical network — from generation to transmission and distribution — serving major public and private stakeholders such as EDF, RTE, ENEDIS, Schneider Electric, Omexom, Bouygues-Equans, CNR, ENGIE and SNCF.

An ETRA Range Adapted to Every Application

ETRA OFFSHORE WIND

The ETRA OFFSHORE WIND oil filled power transformers are designed for marine and coastal environments exposed to severe corrosion, vibration and access constraints. Their design integrates reinforced anti-corrosion protection and architectures adapted to offshore wind farms. It ensures reliable evacuation of power to the grid, with optimized loss performance. Discover ETRA OFFSHORE WIND

ETRA HYDRO

The ETRA HYDRO oil immersed power transformers are specifically developed for hydroelectric power plants, from small installations to large dams. It is dimensioned to withstand rapid load variations related to turbine operation and strict noise and fire safety requirements. Its design optimizes dielectric withstand and insulation lifetime. Discover ETRA HYDRO

ETRA SUBSTATION

The ETRA SUBSTATION oil filled power transformers are designed for transmission and distribution substations (primary substations, MV/HV substations, grid interconnections). It meets the requirements of operators for voltage stability via On-Load Tap Changer (OLTC). These power transformers for substations are used for both new installations and capacity replacement projects. Discover ETRA SUBSTATION

Covered Application Fields

Power Generation and Renewable Energy

ETRA high voltage power transformers are installed close to generation units: onshore and offshore wind, hydropower, solar and photovoltaic plants. Each unit is dimensioned to minimize losses, control temperature rise and contribute to grid stability.

Transmission, Distribution and Railway Traction

For transmission and distribution networks, the SANERGRID Group supplies HV oil-filled transformers for:

  • ENEDIS substations (primary and distribution substations)

  • RTE transmission networks and interconnections

  • Railway traction substations, including TER and TGV applications

Critical Infrastructure and Data Centers

Our medium voltage oil-filled transformers are also adapted to highly demanding environments such as data centers. They are designed for continuous high load regimes and enhanced requirements in terms of reliability and redundancy.

Design, Performance and Key Equipment

Insulation, Tank and Mechanical Safety

The performance of oil immersed power transformers depends on insulation quality. ETRA designs combine optimized paper/oil insulation systems and bushings compliant with required overvoltage withstand levels. The tank is equipped with safety devices (pressure relief valves, oil level indicators) ensuring continuous monitoring.

Protection, Control and Monitoring

High voltage power transformers can integrate a complete protection chain including:

  • Temperature, gas and pressure sensors

  • Protection relays and SCADA interfaces

  • Buchholz relay for internal fault detection Monitoring enables condition-based maintenance for oil-filled power transformers and improved operational anticipation.

From Engineering to Operation: SANERGRID Group Support

Transformer Risk Engineering and Management

The SANERGRID engineering division performs site studies integrating fire, pollution, noise and vibration risks. This expertise results in:

SONEC-KESF: Transformer Commissioning and After-Sales

Field teams handle installation and transformer commissioning in coordination with operators. Since early 2026, SONEC has become the official on-site service entity in France for the KOLEKTOR ETRA Group under the name KOLEKTOR ETRA Service France, ensuring local transformer after-sales service.

KOLEKTOR ETRA Industrial Capabilities and Expertise

The KOLEKTOR ETRA range covers 10 to 500 MVA up to 420 kV. As a leading European power transformer supplier, we offer:

  • Cooling modes ONAN / ONAF

  • Custom power transformers with specific industrial coatings

  • Routine and type testing at the factory (FAT) and transformer commissioning on site (SAT)

  • Coordinated turnkey delivery and handling to secure schedules.

Accessories and Spare Parts via TECHNIKELEC

To facilitate maintenance for oil-filled power transformers, the TECHNIKELEC platform offers a selection of accessories:

  • Insulators and gaskets

  • Oil level indicators and pressure sensors

  • PTFE plates and MV/HV protection solutions Technical support is available to validate reference compatibility for your oil filled power transformers.

Why Work with the SANERGRID Group?

A Comprehensive and Coherent Approach

Beyond transformer supply, the SANERGRID Group masters related challenges: dielectric oil management, fire prevention, and transformer risk engineering and management. This cross-disciplinary approach simplifies multi-lot projects.

Responsiveness, Proximity and Support

With teams based in France and a European industrial network, we prioritize direct technical exchanges and strong field proximity to secure timelines and guarantee optimal installation availability.

Your Oil-Immersed Power Transformer Project

Are you preparing a power generation, transmission or distribution project? Send us your key parameters. We will propose a custom power transformers architecture adapted to your project, integrating energy performance and safety requirements.

Contact the SANERGRID Group for an initial technical discussion, budgetary estimate or site visit.