Reliable Energy Supply for the city of Graz, Austria

In order to improve the energy supply for the city of Graz, CCC GmbH Berlin installed new cable connections across the town between the transformer stations of Graz-South and Graz-West. The entire underground engineering, i.e. the joint base installation mand complete trenching construction was built by STEWEAG-STEG GmbH. The new cable installation is one of the city’s main transmission lines and is heavily loaded. In order to optimize the transmission performance and to guarantee its secure reliability, the cable installation has been equipped with large scale cross-bonding systems at its sheath. In addition, by the help of the LIOS Distributed Temperature Sensing (DTS) system, the level of backup capacity can be assessed. These optical fibres can monitor the cable temperature along the trench and have been integrated into the sheath area of the cable.

Highlights

• 110 kV high-voltage power cables between transformer stations Graz-South and Graz-West
• 3 cable lines with a length of 3,2 km each (total 9,6 km cable),one of which is equipped for the entire distance of 3,2 km with integrated optical fibres in a steel tube integrated in the copper screen of the HV-cable for temperature monitoring (DTS)
• 18 sets of accessories
• Cross-bonding system in order to maximize transmission performance
• During the planning period numerous calculations for currentcarrying capacity were carried out in order to judge the influenceof crossing long-distance heating lines.
• Direct DTS data interface for temperature and operational data into the overall SCADA system of STEWEAG-STEG (Fernwirkanlage STEWEAG-STEG) using protocol IEC 60870-5-104