Primary- and Secondary Systems for the Substation Nord (Wels Strom)


Medium voltage switchgear (double busbar) inclusive redundant station control

As a subsidiary of the Elektrizitätswerk Wels AG and the Energie AG, Wels Strom GmbH acts as the local electricity supplier for the area of Wels (Upper Austria).

In order to guarantee electricity supply for the city of Wels, the 10 kV grid in the north-western area of Wels had to be expanded by a new substation.

The new substation “Umspannwerk Nord” was built for meeting the increasing electricity demands and for supporting existing stations, which finally leads to a higher supply security.

It is assumed, that especially in this area power demand is going to increase most. Also, the location of the substation “Nord” provides ideal connection possibilites to the existing high voltage grid.

As the main contractor, Sprecher Automation was assigned to deliver the 12 kV medium voltage switchgear (10 kV operating voltage) as well as the secondary systems for the 110 kV and the 10 kV switchgears.


SPREPOWER MV-M6-DSS: air-insulated medium voltage switchgear with pressure release outwards
DURESCA busbars

Innovative medium voltage concept with secondary systems

SPREPOWER Medium voltage switchgear

SPREPOWER MV-M6-DSS was applied as the main medium voltage switchgear, which is type-tested against EN 62271-200. It is designed as for double busbars and equipped with a pressure release duct. The main switchgear covers 22 bays (31.5 kA/1 sec., 2500 A).

The transformer bays of the medium voltage switchgear are connected to the transformers with DURESCA® busbars (2000 A).

The installation of these fully insulated and shock-proof busbars guarantees highest possible operation safety and availability.

Beside the main switchgear Sprecher Automation also delivered the medium voltage switchgear (SPREPOWER MV-M1) for the auxiliary systems, which is designed as a single busbar switchgear with 10 cubicles (25 kA/1 sec., 630 A).

Sprecher Automation also installed components of the AF (audio-frequency) remote control system into two cubicles of the switchgear for the auxiliary systems. The modulation of the audio-frequency (1996 Hz) takes place within a 10 kV oscillating circuit. The system is used for control of domestic water heating, security services, street lighting and heat pumps.

Bay overview of the SPREPOWER MV-M6-DSS switchgear


Redundant SPRECON-E station control system

In addition to the switchgears, Sprecher Automation installed all secondary sytems (SPRECON-E) for the high and medium voltage switchgears.

The station control system consists of redundant station computers and is remote-maintained by Sprecher Automation. Both station computers are connected to a control center via IEC 60870-5-104.

Beside engineering and design of circuit diagrams, Sprecher Automation also performed the overall installation and commissioning works.

In October 2007, all delivered systems were put into full operation.

SPRECON-E station control system for the high and medium voltage switchgears of the substation “Nord”