Coal, O&M

Siemens supplies new design high-voltage switchgear to REE

14 March 2005 – In cooperation with the Spanish energy supplier and network operator Red Eléctrica de Espana (REE), Germany’s Siemens Power Transmission and Distribution (PTD) has developed a new substation concept, based on Highly Integrated Switchgear (HIS).

The gas-insulated substations are designed for outdoor installation and require about 70 per cent less space than comparable air-insulated equipment. By the end of 2004, two of these 420 kV HIS systems had been commissioned in Spain in a new novel ring configuration.

The design of the substations reflects a solution developed by REE on the basis of HIS modules. In this arrangement, known as New Segregated Ring (NSR), the circuit-breakers are grouped by poles. This allows not just new designs but innovative termination solutions too and enhanced availability of the overall system. A circuit-breaker module can be replaced in six hours.

The gas-insulated 420 kV HIS set up in the Palos de la Frontera transformer substation in southern Spain was the world’s first to feature outdoors the new ring arrangement devised by REE. The individual circuit-breaker modules are arranged in a ring and linked by way of encapsulated assemblies such as tubes, expansion joints and angle-type enclosures. At the corners of these resulting closed rings the switchgear is linked by means of outdoor bushings to the lattice of cables above, via which for example transformers and overhead lines can be connected. All the advantages of enclosed outdoor switchgear are provided, along with considerable versatility and scope for making terminations.

The units comprised circuit-breaker modules (fully assembled and tested in the Berlin manufacturing plant) with built-on transformers, disconnectors and enclosures for connection of the outdoor bushings. At the site, it was then possible to unload the complex components (of more than 7.5 meters in length) directly from the truck onto the preassembled framework. This reduced the effort involved in installation and testing, as well as the risk of errors.

Siemens likewise conceived the breaker pole modules such that they can be brought to the site as fully tested and mounted transport units. This design further makes it possible to replace a circuit-breaker (in the event of a fault or maintenance) within only six hours without having to shut off the power at the outdoor bushings – a notable additional advantage for the operator.