New clamping technology for shunt reactor production successfully implemented globally

Shunt reactors are basically composed of an active part, frame structure and tank. The active part mainly consists of the gaped core limb, winding block, yokes, return limbs and clamping structure (tie rods, traverses). Once assembled, the different parts need to be clamped and locked between the upper and bottom yokes using tie rods, to ensure that the whole assembly is tight enough to withstand the transport accelerations and safely operate in the high voltage power grid.

The former design was cost intensive due to the needed expensive high-tensile-steel for traverses and tie rods. In addition, the traverses increased the height of the reactor’s active part by approximately 30 centimeters.

Siemens Energy employees at the Power Transformer Technology Center developed a new design version designated as the "New Clamping Concept" and the Siemens factory in Brazil was selected to prototype the solution. The developed design reduces the active part dimensions by improving the assembly structure between the upper yoke, the main core and the return limbs. By changing the step lap construction, it was possible to increase the contact area between the core sheets, which are compressed by screw fittings. This increases the friction and holds the whole assembly tight and under pressure. The clamping force on the core column is applied and maintained by the yokes and the return limbs. Accordingly, this new clamping technology eliminates the external tie rods and traverses, which lowers the active part by an average of 30 centimeters.

The New Clamping Concept was used the first time in 2019 to assemble the active part of a shunt reactor. Now the concept has been rolled out to the complete shunt reactor factory network and almost seventy units have been built.

Shunt reactors built with the New Clamping Concept features include:

• significantly reduced active part dimensions, tank dimensions
• less insulation oil, lower weight and consequently reduced costs for transportation

Transmission products play a vital role in the energy value chain. Siemens Energy Transmission offers all key elements including power and distribution transformers, gas-insulated and / or air-insulated switchgear and associated components, individually, bundled or as a system with related engineering and service. Our global factory network and innovations help provide the highest level of quality and reliability to support our customers’ operational and environmental objectives.