When modernizing plants, AVU Netz GmbH relies on a sophisticated interface concept. New power transformers are equipped in such a way that they can cover all the relevant interface configurations encountered in the AVU network. How well this functions in practice is demonstrated by the three new 110/10-kV transformers in the 50 MVA performance class at their respective locations. The identically constructed transformers are connected differently according to need. This is possible because at all phases and neutral points, CONNEX device connection components are permanently integrated into the power transformers. By means of these components, various dry-insulated CONNEX components can be plugged in quickly and easily, without having to intervene in the inner workings of the systems.
“The more transformers are equipped with CONNEX, the more flexible is our plant system overall"
says Volker Jost, who has project responsibility as a member of the High-Voltage Systems Team at AVU Netz GmbH. The intelligent connection-pairing of the third transformer, located in the Altenvoerde substation, is also forward-looking. The HV-CONNEX connecting components located at the base are equipped with cables that connect to gas-insulated switchgear in the neighboring building. The interfaces at the location that are not required for the horizontal bushing connection are sealed with blanking plugs of high electric strength.
Suited to the location – in the AVU substation at Witten this meant connecting the transformer located outdoors to existing gas-insulated switchgear in a building without making any modifications. A smart solution is achieved here with HV-CONNEX bushings on the high-voltage side of the transformer. These bushings are connected with cables via intermediate surge arresters on existing SF6 gas-insulated wall bushings. In the AVU substation at Schwelm, on the other hand, the local situation demanded a conventional connection of the second transformer to the outdoor switchgear. Yet the standard configuration offers room for mobility because the HV-CONNEX bushings can also be inserted horizontally. This corresponds with the profile specifications of Germany’s Deutsche Bahn railway company. In an emergency, the transformer can thus be temporarily moved by rail or low-loader to one location or another, in order to replace a damaged transformer at that location.