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Rearranging and cable shifting at the Nieder-Wöllstadt substation


Due to the advanced age of the system, the Nieder-Wöllstadt substation needed some amendments. In order to implement the required service, EQOS Energie performed the upgrades to the 110-kV system and shifted the 20-kV cables to new switchgear. Over the course of 14 months, the company disassembled and reconstructed the two 110-kV line bay and two transformer cubicles including busbar and foundations.

The goal of this project was to implement extensive rearrangement in order to increase supply security based on a modernised distribution network as well as operational reliability for the network and the system. In addition, the 110-kV and 20-kV networks were to be modernised. To accomplish these goals while continuously safeguarding power supply for consumers, EQOS Energie performed disassembly and fitting in two steps of construction in order to continue the supply to the existing transformer and subsequently the switchgear.

The project started with the disassembly of the first transformer cubicle and subsequent reconstruction. Additionally, an arc suppression coil foundation was incorporated. Next, the medium-voltage system which had already been constructed was fed in and the feeder cables for the local network were shifted to the new part of the system. This process was repeated for the second line bay. To conclude the project, EQOS Energie upgraded the transformer access road and rebuilt the surfaces. The work required great caution in distinguishing between the necessary secondary cables, since part of the work was conducted on an active high-voltage system. In addition, provisional set-ups had to be constructed in order to be able to continue operation of parts of the existing system. Due to space constraints of the system, a 400-tonne mobile crane was deployed for the placement of the 110-kV transformers.

Despite a longer break during the winter, the project was completed on time.

The project

  • Customer: OVAG Netz AG
  • Wöllstadt, Germany
  • Period of construction: June 2016 to August 2017

Overview of services

  • Disassembly of 2 line fields, 110 kV, 2 transformer cubicles, busbar, cable dismantling, including foundations
  • Delivery and fitting of the steel construction/equipment supports
  • Overall coordination, earth measurement, medium-voltage measurement, participation in functional testing and commissioning
  • Installation of approx. 3,000 metres of medium-voltage cable

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