Joint Press Release

"Öko-R-ONT" of SBG Neumark put to practical test at Netze BW

Doubly-innovative transformer in a local network station in the Ravensburg district Bodnegg. How does vegetable oil behave as insulator in a controllable transformer? Netze BW and Sächsisch-Bayerische Starkstrom-Gerätebau (SBG) have been investigating this question since the Easter week in a local network station in Bodnegg (rural district of Ravensburg].

According to the Managing Director Erwin Birbacher, approximately 700 of the controllable transformers (‘R-ONT‘) built by the Neumark/Saxony-based SBG have already been installed at distribution network operators’ in Germany. Local network transformers operated with vegetable oil have been tested by Netze BW in approx. 70 sites so far. Martin Konermann, Technical Director of the EnBW subsidiary, assumes that “we are probably the first by far to combine these two technical innovations”.

The low-voltage level of Netze BW is increasingly subject to voltage fluctuations due to an especially high density of photovoltaic systems, as is the case in the area of Rotheidlen, a part of Bodnegg. The expected increase in the number of electric recharging points could aggravate these fluctuations in maximum-load phases even further. The auto-controlling transformers stabilize the grid. “Thus, we can avoid a costly and often time-consuming expansion”, states Konermann. Thanks to an innovative on-load tap changer made by Maschinenfabrik Reinhausen, SBG’s R-ONT provides additional benefits, according to Birbacher: “It is able to switch in on-load condition and to complete switching operations under all conditions". Moreover, it has the same footprint as its conventional counterpart. This is practical for Netze BW, as it fits into the existing station perfectly.

Netze BW will equip a total of 102 of its approx. 26,500 local network stations in Baden-Wurttemberg with ‘eco transformers'. Special measuring systems determine the behaviour of the insulating fluid, which is primarily obtained from oilseed rape, under hot, cold and humid conditions or under high UV exposure. However, remote monitoring from Stuttgart also covers the operating data at Bodnegg for automatic voltage control. The background of the vegetable oil project: mineral oil is not admissible for operation of transformers, especially in ecosensitive areas such as water conservation areas. The alternatives implemented so far are considered to be technically complex and, moreover, costly. If test results prove to be positive, future transformers could do without mineral oil completely.