“We don’t have to advertise much”

Säch­sisch-Bay­erische Stark­strom-Geräte­bau GmbH (SBG) is a lead­ing man­u­fac­tur­er of dis­tri­b­u­tion trans­form­ers and spe­cial equip­ment. SBG was one of the first com­pa­nies that decid­ed to inte­grate the new ECOTAP VPD on-load tap-chang­er into its reg­u­lat­ed dis­tri­b­u­tion trans­form­ers. Man­ag­ing Direc­tor Erwin Bir­bach­er and Sales Engi­neer Michael Büh­n­ert report on their expe­ri­ences.


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 out­set that we want­ed to work 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 stand 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 & play solu­tion that is inter­est­ing for all users who want to improve their net­work qual­i­ty. In addi­tion to sup­ply net­work oper­a­tors, this also applies to indus­tri­al com­pa­nies that have increased demands in rela­tion to a sta­ble volt­age band in the net­work due to sen­si­tive process­es.

What sets the VRDT with ECOTAP VPD apart?

BÜHNERT:A key advan­tage is the abil­i­ty to inte­grate the VRDT into exist­ing infra­struc­tures. The VRDT foot­print, i.e., the floor space that it occu­pies, is near­ly iden­ti­cal to that of its unreg­u­lat­ed coun­ter­part. In addi­tion, it can switch under load and com­plete tap changes under all con­di­tions. 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 net­work, or as a sup­port to sta­bi­lize the medi­um-volt­age net­work. In addi­tion, the tap-chang­er does not cause any addi­tion­al loss­es. This is not only impor­tant in terms of effi­cien­cy, but also in terms of heat devel­op­ment.

Was it a complicated development process to get the VRDT ready for series production?

BIRBACHER: We are gen­er­al­ly very quick at design­ing a func­tion­al mod­el. Ulti­mate­ly, we were deal­ing with a trans­former with addi­tion­al taps, which we then opti­mized over the course of many devel­op­ment steps. It was there­fore pos­si­ble to test var­i­ous wind­ing and reac­tor designs. As a result of devel­op­ing our own reac­tors and thanks to their instal­la­tion posi­tion, we were able to halve the addi­tion­al loss­es in bridge posi­tions, as well as fur­ther opti­mize the size and sound emis­sion. We were able to improve these aspects even more by chang­ing to the high-speed resis­tor-type tap-chang­er prin­ci­ple of the ECOTAP VPD. We worked close­ly with Rein­hausen on all the steps, and we have both prof­it­ed great­ly from this coop­er­a­tion. We have been sup­ply­ing ser­i­al-pro­duc­tion VRDTs since 2012. By now they are part of the stan­dard oper­at­ing equip­ment for ener­gy providers.

Were there any difficult obstacles during this optimization phase?

BÜHNERT: There were three main points. 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 from 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 with regard to the oper­at­ing tem­per­a­ture.

How easy was it to integrate the VRDT into live production?

BIRBACHER: We are used to pro­duc­ing spe­cial solu­tions. There­fore, series pro­duc­tion was not a prob­lem. The tap-chang­er is very easy to inte­grate with­out any spe­cial tools. Nor­mal­ly, we install de-ener­gized tap-chang­ers, which can be switched off, in dis­tri­b­u­tion trans­form­ers. These are adjust­ed accord­ing­ly to match the grid volt­age. The prin­ci­ple is basi­cal­ly the same, except that the ECOTAP VPD is slight­ly larg­er and heav­ier in com­par­i­son to tap-chang­ers that can be switched off.

How do you rate the market potential?

BIRBACHER:Around 70 per­cent of the approx. 1,000 VRDTs in Ger­many were pro­duced by SBG. The emer­gence of oth­er mar­kets will obvi­ous­ly depend on how the respec­tive gov­ern­ments pro­mote alter­na­tive ener­gies. Among oth­er things, we see fur­ther poten­tial in the expan­sion of e‑mobility infra­struc­tures. We main­ly attract sup­ply net­work oper­a­tors and ener­gy sup­ply com­pa­nies, and of course we also car­ry out projects direct­ly with indus­tri­al cus­tomers and com­pa­nies for alter­na­tive ener­gy gen­er­a­tion. For exam­ple, we can sup­ply wind ener­gy plants with con­trol tech­nol­o­gy, which means that the feed-in already has the opti­mum volt­age qual­i­ty. Over­all, we are in a growth mar­ket with the VRDT.


Share with your network!

Never miss an issue again!

Click here to subscribe for free.