Specialist areas

New constructions (national)

Umspannwerk National


In general electricity is not actually used where it is produced. The electrical energy that is generated in wind turbines or solar power plants therefore has to be fed into the supply grid.

These transport networks operate with different voltages, regional networks, for instance, with voltages of around 110 kV, local distribution networks, however, only with voltages of 30 kV to 60 kV. A transformer station has to be constructed in order to connect these networks with one another.

After the completion of the planning the civil engineering work begins, a site road may be created depending on the individual requirements. Following this, all the necessary foundations and control and monitoring buildings will be erected. Finally, the core item, the transformer, is installed. Elaborate structural measures have to be taken into account here. Thus in the case of oil-filled transformers, an oil pan is always installed under the transformer in order to meet the required levels of environmental protection.

The construction time alone for a single transformer station at WT Energiesysteme GmbH is usually only 16 weeks. The work is completed by means of the acceptance by the energy supply company and the subsequent connection to the high voltage grid.

New constructions (international)

Neubau International


With over 15 years of experience and more than 100 start-ups, we are strong enough to penetrate the international market. WT Energiesysteme GmbH has put together a flexible, strong and international team to this end.

In 2016, we were awarded a contract for the construction of several transformer stations in Europe’s largest onshore wind farm of Markbygden in northern Sweden. Huge turbines with rotor diameters of 137 metres respectively are being constructed there. As the partner of „GE Renewable Energy“, of the „Wood Group“ and the „Green Investment Group“ we also help to ensure the connection of the wind turbines to the Swedish power grid.

With a total output of 4GW it will become the biggest onshore wind park at a European site and increase the installed basis of wind turbines in Sweden by more than 12.5 per cent. For international operations we rely on employees from the respective region and on training courses on the language and culture. Our teams not only consist of specialists, but also flexible allrounders who are able to familiarise themselves with different specialist fields and thus support their colleagues. Due to the international makeup of our team we also have advantages in terms of our knowledge of the country-specific regulations.

The topic of environmental protection is gaining increasing importance worldwide. Germany is a pioneer in many areas there. We can make use of this experience in our international operations. Our customers benefit from the fact that we consider the environmental protection aspect in every project. Due to our experience with this topic, we are able to respond flexibly, rapidly and reliably to the respective challenges at hand.


Umspannwerk Rielasingen


Sooner or later every transformer station has to be either retrofitted or modernised. The reasons for this are frequently due to age-related wear and tear, sometimes in new statutory regulations, but also often due to the ever increasing energy demand.

The conversion of an existing transformer station is a much bigger challenge than the construction of a new one. In principle the transformer station should remain connected to the power grid for as long as possible. This means that the conversion is usually performed while the plant is still “live” – it requires increased caution, experience and competence of the employees. In addition, in most reconstructions old and new control technology must be merged.

With our diverse team, we are able offer all the retrofitting services from a single source. As in the case of new buildings you also only work with one contact here. This is, due to the short decision-making paths involved, a major advantage of working with a medium-sized company such as WT Energiesysteme GmbH.

Extra high voltage

Umspannwerk Höchstspannung

Transformer stations between local distribution networks, which switch from, for instance, 6 kV to 30 kV, are often designed as indoor installations. Outdoor facilities are generally constructed when transforming voltages from inter-regional distribution grids to regional grids. However, the largest transformer stations are those for the extra high voltage lines of up to 380 kV for the national transport networks, such as the planned north-south route by the name of Südlink (southern link).

For the construction of transformer stations, we provide comprehensive services in the areas of planning, project planning, assembly, modernisation, maintenance and documentation. With our many years of experience, we are partners of energy suppliers both in the performance of individual tasks and also for the complete realisation of turn-key projects.

Our services for your transformer stations and switching stations with outputs of up to 380kV:

  • Project planning of construction technology, primary and secondary systems as well as telecontrol and station control technology with CAD support
  • Impementation of the approval procedure for your projects
  • Construction of factory buildings, foundations for equipment benches, transformers and portals, as well as civil engineering works
  • Supply and assembly of all the steel constructions (tables, stanchions, portals, scaffolding)
  • Supply and installation of switchgears / switchgear systems, transformers, devices for earth fault treatment
  • Supply and assembly of the auxiliary power supply
  • Construction of the cable networks (power cables, secondary cables)
  • Construction of the earthing network and earthing measurement – Construction of the entire infrastructure (roads, paths, lighting, fencing, monitoring, sewage and oil-water treatment)- Project management and auditing of the secondary project with CAE support – Execution of tests and controls for all system parts – Implementation of parameterisations and tests of control and protection equipment and telecontrol equipment
  • Implementation of the start-up inspections
  • Servicing, maintenance and modernisation
  • Setting up of provisional arrangements for the site clearance, e.g. with 110 kV field installation cables
  • Consultancy relating conversion solutions and plant upgrades