SBG was one of the pioneers in the field of regulated distribution grid transformers. Since as early as 2012, the transformer manufacturer has produced VRDTs with the ECOTAP® VPD® on-load tap-changer from Reinhausen. Managing Director Erwin Birbacher and Head of Sales Michael Bühnert report on their experiences.
"We are in a growth market with the VRDT"
Since 2012, Saxon-Bavarian Starkstrom-Gerätebau GmbH (SBG) has been delivering series-production VRDTs (regulated local grid transformers). Since then, they have become established as standard operating equipment for energy providers.
"We are in a growth market with the VRDT"
Since 2012, Saxon-Bavarian Starkstrom-Gerätebau GmbH (SBG) has been delivering series-production VRDTs (regulated local grid transformers). Since then, they have become established as standard operating equipment for energy providers.
In order to manufacture a regulated distribution transformer, you have chosen to use on-load tap-changers from Reinhausen. Why?
BIRBACHER: For us, it was clear from the start: We would team up with a strong partner, agree on the interfaces and develop a product that was reliable, safe to operate and, above all, could be launched on the market quickly. Both of our companies have an excellent reputation and are known for many years of experience, quality and longevity. If we say that we combine SBG expertise with Reinhausen tap-changer technology, we don't have to advertise much more than that.
BÜHNERT: One major advantage is that we offer a plug-and-play solution that is useful for all users who want to improve their power quality. In addition to supply grid operators, this also applies to industrial companies that have increased demands with regard to a stable voltage band in the grid due to sensitive processes.
What sets the VRDT with ECOTAP® VPD® apart?
BÜHNERT: The VRDT footprint, i.e. the floor space that it occupies, is nearly identical to that of its unregulated counterpart. It can switch under load and we can cover the entire voltage band with a control bandwidth of plus/minus ten percent. For example, the VRDT can be used as a direct regulator in the low-voltage grid or to stabilize the medium-voltage grid. Furthermore, the tap changer does not cause any additional losses. It is not only efficient, it also does not generate any additional heat.
„The VRDT can be used as a regulator in the low-voltage grid or to stabilize the medium-voltage grid.“
Was it a complicated development process to get the VRDT ready for series production?
BIRBACHER: Designing a functional model generally goes very quickly. We also tested various winding and reactor designs. As a result of developing our own reactors and thanks to their installation position, we were able to cut the additional losses in bridge positions in half and also optimize the size and sound emission. We were able to improve these points by switching to the ECOTAP® VPD®.
Were there any obstacles during this phase?
BÜHNERT: There were three main ones. First of all, it was difficult to coordinate the interfaces between the transformer, the tap changer and the control technology. In addition, a transformer with a tap changer behaves differently than a conventional one. This was something that we had to consider during the design phase. The third point was the behavior with alternative insulating media. Due to the internal mechanics, there was a lot to consider when considering the operating temperature.
„The VRDT's footprint is nearly identical to that of its unregulated counterpart.“
How easy was it to integrate the VRDT into production?
BIRBACHER: We produce many special-purpose solutions. Therefore, series production was not a problem. The tap changer is very easy to integrate. Normally, we install de-energized tap-changers that can be switched off in distribution transformers. They are adjusted to match the line voltage accordingly. The principle is basically the same. The ECOTAP® VPD® is just a bit larger and heavier.
How do you rate the market potential?
BIRBACHER: Which markets open up will depend on the spread of alternative energies. We see further potential in the expansion of e-mobility infrastructure. We attract supply grid operators and energy supply companies and we carry out projects directly with industrial customers and companies for alternative energy generation. For example, we can equip wind energy plants with control technology, which means that the feed-in already has the optimum power quality.
