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The “Stadtwerke Crailsheim” (regional public utility Crailsheim) is expanding its grid – and thus positioning itself for the future. This will enable them to meet the new requirements resulting from the increased integration of renewable energies and the expansion of charging infrastructure for electromobility. As part of the expansion, a medium-voltage switchgear had to be extended, and we supplied eight new switchgear panels for this purpose. In close cooperation, a customized solution was created that enabled the smooth integration of the new panels into the older, excisting switchgear panels.
Stadtwerke Crailsheim has provided its customers with energy reliably for over 100 years. Today, the company operates power supply lines with a total length of almost 1,000 km to provide electricity, gas, district heating and drinking water in the Crailsheim network area. The energy supplier always lives up to its claim of keeping its networks technically up to date. This was also the case in 2011, when air-insulated medium-voltage switchgear with double busbars from the 1960s was replaced by a new switchgear building as part of a modernization project. At that time, Ormazabal equipped this with 16 cpg.1 switchgear panels. Since then, the utility has covered two districts with the system.
“In order for a third substation district to be added, we decided to expand the existing facility,” says Michael Weidner from Stadtwerke Crailsheim, explaining the reason for an extensive conversion measure in the substation. “The fact that we again relied on Ormazabal’s expertise was the logical consequence,” says Weidner, who is convinced of the advantages of cpg.1 after several years of experience with the system. Crucial for the decision were product features such as the space-saving design, the simple expansion option through use of external, solid-insulated busbars, the minimal maintenance effort through the use of a hermetically sealed gas tank combined with vacuum switching technology, as well as the clear operability. Consequently, we manufactured and supplied a total of eight new switch panels of cpg.1 to be integrated into the existing plant.
Our know-how as an expert in energy distribution was particularly beneficial with regard to connecting the new switchgear panels to those that were already more than ten years old. Although this is a common process for suppliers of medium-voltage technology like us, it requires the planning of an individual and customer-specific approach due to further technical developments.
“Of course, we have optimized our cpg.1 over time. We have improved both the external appearance, i.e. housing design and colour scheme, as well as technical details,” says Thomas Höfkens of the German Solutions Team, which supported our customer in connecting the functionally and visually revised versions of the cpg.1 securely to the predecessor models, both mechanically and electrically.
To ensure a quick and smooth connection, we developed a customized solution. The connection points of the cpg.1 double busbar have not changed, but since the newer versions no longer have doors in front of the operating areas, the operating front is slightly further back than before. In order to be able to integrate the required secondary technology components and another DC/DC converter, larger relay boxes were required. These could be connected to the relay boxes of the existing panels via a specially developed adapter. The new panels also had to be integrated into the interlocking system of the existing system. Here, various interlocks were made, for example between the switch panels and the busbar coupling panels, which prevent a faulty connection from both busbar sections via the feeder panels as long as the coupling is not switched on. Furthermore, our solutions team equipped the fields with up-to-date power differential protection and distance protection devices and prepared them for the integration of telecontrol technology on the part of Stadtwerke Crailsheim. For this purpose, it was necessary to wire all signals to a transfer terminal strip and to install a corresponding transducer for the measured values.
As a provider of innovative complete solutions, we were responsible for the customer-specific production and delivery of the systems. But also, our team coordinated the entire process starting with planning, mechanical as well as electrical assembly, installation, renewal of the old equipment including high-voltage testing and PD measurement up to commissioning and final acceptance. “Ormazabal provided us with reliable support from start to finish,” says Weidner. The good cooperation was evident, among other things, during the on-site installation, which our Solutions Team supervised. The connection of some switchgear panels, which could not be carried out during ongoing operation, was managed jointly by the employees of both companies on a weekend assignment during the off-peak phase.
For this, a timing was defined at which the grid load was as low as possible and the output from renewable energies as high as possible. This meant that the supply could run via just one transformer and the second one could be switched off for the conversion. To do this, there was a precise scheduling requirement on the part of Stadtwerke Crailsheim so that the security of supply to end consumers could always be ensured without interruption. “This worked flawlessly,” Weidner sums up. “After one day, the cubicles were fully connected and ready to be switched on. In particular, the time flexibility that Ormazabal displayed made me feel very positive – just like the strong solution orientation, even in challenging circumstances.”
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