More power for the grids! 

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Regens­burg in the sum­mer of 2025. Series pro­duc­tion of the new VACUTAP^® VI begins. Five years of devel­op­ment work have gone into the inno­v­a­tive tap-chang­er con­cept, which takes up sig­nifi­cant­ly less space than con­ven­tion­al on-load tap-chang­ers. All tests have been passed, and now the time has final­ly come for it to con­quer the world’s trans­form­ers. In August, the first two new tap chang­ers leave the fac­to­ry. One is on its way to Czechia, not far from the Pol­ish bor­der, but only for a stopover; it will even­tu­al­ly be put into ser­vice in Geor­gia. The oth­er is head­ed to the far north of Nor­way. There, the VACUTAP^® VI will even be used in an appli­ca­tion for which it was not orig­i­nal­ly intend­ed. Two site vis­its. 

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More power in the substation 

Elpro-Ener­go Trans­form­ers s.r.o., based in Hno­jník, Czech Repub­lic, is still a rel­a­tive­ly young com­pa­ny, but since its found­ing in 2018, it has quick­ly become a sought-after man­u­fac­tur­er of dis­tri­b­u­tion trans­form­ers. Today, Elpro-Ener­go Trans­form­ers employs around 130 peo­ple and pro­duces up to 3,000 trans­form­ers annu­al­ly, pri­mar­i­ly for dis­tri­b­u­tion net­work oper­a­tors, but also for indus­tri­al com­pa­nies, pow­er plants, and pub­lic insti­tu­tions such as hos­pi­tals. usi­ness is going well, but the mar­ket served by the Czech man­u­fac­tur­er is also very volatile, as elec­tri­cal engi­neer Miroslav Mra­j­ca reports:

“Last year, for exam­ple, there was strong demand for trans­form­ers for pho­to­volta­ic sys­tems, where­as demand is sig­nifi­cant­ly low­er this year. We adapt to these fluc­tu­a­tions by also focus­ing on areas where com­pe­ti­tion is weak­er.” Com­pe­ti­tion is par­tic­u­lar­ly fierce in the stan­dard trans­former sec­tor, espe­cial­ly when it comes to price. One impor­tant lever for remain­ing com­pet­i­tive is there­fore the effi­cient use of key mate­ri­als such as alu­minum, cop­per, and elec­tri­cal steel. Anoth­er lever is inno­v­a­tive prod­ucts that enable the trans­former man­u­fac­tur­er to stand out from the crowd. Mra­j­ca explains: “This requires opti­miz­ing trans­former designs while at the same time fur­ther devel­op­ing trans­form­ers with mod­ern tech­nolo­gies.”

A product that was still missing 

Elpro-Ener­go Trans­form­ers there­fore wel­comes inno­va­tions such as the new VACUTAP^® VI on-load tap-chang­er. The com­pa­ny has used this inno­v­a­tive switch con­cept for the first time in a trans­former with a capac­i­ty of 2,500 kilo­volt-amperes for a cus­tomer in Geor­gia. The cus­tomer want­ed a very com­pact solu­tion, but with a rat­ed volt­age of 6 kilo­volts, the cur­rent exceed­ed 100 amperes.  

This was too high for the ECOTAP^® VPD^® from MR, which Elpro-Ener­go Trans­form­ers usu­al­ly uses for such appli­ca­tions. The very com­pact design of the VACUTAP^® VI, com­bined with its high per­for­mance, there­fore imme­di­ate­ly con­vinced Mra­j­ca. The new tap chang­er can  

han­dle cur­rents of up to 400 amperes at up to 27 tap posi­tions. “The advan­tage is that the tank and cov­er of the trans­former do not require any spe­cial mod­ifi­ca­tions, except for a built-in flange plate, which great­ly sim­plifies cal­cu­la­tions and draw­ings in the plan­ning phase. In addi­tion, con­nect­ing the wind­ings to the tap-chang­er con­tacts is straight­for­ward, as all out­puts are locat­ed on one side,” says Mra­j­ca.

This makes assem­bly very quick and easy for pro­duc­tion per­son­nel. Mra­j­ca also sees a major advan­tage in the fact that the shared oil sup­ply means that the tank size can be small­er, which not only saves mate­r­i­al but also requires less oil. This is not only an impor­tant plus point in terms of costs and the envi­ron­ment, but also opens up new oppor­tu­ni­ties for grid oper­a­tors because the space required for trans­form­ers in sub­sta­tions is reduced–while per­for­mance lev­els are main­tained.  

Elec­tri­cal engi­neer Mra­j­ca is also impressed by the inno­v­a­tive direct dri­ve and auto­mat­ic con­trol sys­tem, which com­plete­ly elim­i­nates the need for dri­ve shafts: “I expect high­er pre­ci­sion and reli­a­bil­i­ty with low­er main­te­nance require­ments, faster response to grid fluc­tu­a­tions, improved volt­age sta­bil­i­ty, and intel­li­gent mon­i­tor­ing. Over­all, this should lead to high­er effi­cien­cy, greater secu­ri­ty, and a longer ser­vice life.”

The trans­former for the Geor­gian cus­tomer is there­fore unlike­ly to be the last one that Elpro-Ener­go-Trans­form­ers equips with the VACUTAP^® VI. Mra­j­ca sees great poten­tial, espe­cial­ly for small­er trans­form­ers where larg­er vac­u­um tap chang­ers would be over­sized but the ECOTAP^® VPD^® reach­es its per­for­mance lim­its. “I think such a prod­uct has been miss­ing in the OLTC mar­ket until now,” says Mra­j­ca.

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Increased capacity for the medium-voltage grid 

With its majes­tic fjords, rugged moun­tains and deep val­leys, thou­sands of lakes and vast forests, Nor­way is known for its unspoiled nature. With a pop­u­la­tion of just under six mil­lion inhab­i­tants in an area rough­ly equiv­a­lent to that of Ger­many, the coun­try is very sparse­ly pop­u­lat­ed. Except for urban cen­ters such as Oslo, Bergen, and Trond­heim in the south and south­west, many com­mu­ni­ties and towns are scat­tered far apart and often very remote. What makes the land­scape so appeal­ing is a real chal­lenge for reli­able pow­er sup­ply. Since medi­um-volt­age lines from the grid con­nec­tion point to the near­est set­tle­ment are often twen­ty kilo­me­ters or longer, keep­ing the volt­age sta­ble for con­sumers here is any­thing but easy. In addi­tion, elec­tric­i­ty demand fluc­tu­ates great­ly between win­ter and sum­mer, as heat­ing in Nor­way is pre­dom­i­nant­ly elec­tric.  

Magtech AS, based in Steinkjer, spe­cial­izes in prob­lems like these. Found­ed in 2001, the com­pa­ny o«ers inno­v­a­tive solu­tions for volt­age reg­u­la­tion and grid opti­miza­tion and man­u­fac­tures volt­age reg­u­lat­ed dis­tri­b­u­tion trans­form­ers and volt­age boost­ers as well as volt­age reg­u­la­tors for medi­um-volt­age net­works (MV reg­u­la­tors). An MV reg­u­la­tor com­pen­sates for volt­age drops or ris­es in the mid­dle or last third of long lines. But it can do even more, as Alexan­der Kris­tensen, CCO at Magtech, explains: “Even if the ther­mal capac­i­ty of the line is avail­able, the volt­age drop means that, with­out reg­u­la­tion, not all of the pow­er can be trans­mit­ted. Depend­ing on the design, an MV reg­u­la­tor can even triple the capac­i­ty of a line.” This elim­i­nates the need for com­plex and cost­ly grid expan­sion.

In addi­tion to Nor­way, the main sales area for Magtech’s solu­tions is pri­mar­i­ly the oth­er Scan­di­na­vian coun­tries, as they face sim­i­lar chal­lenges. And demand for MV con­trollers is increas­ing with the grow­ing loads on the grid. In addi­tion to new con­sumers such as elec­tric cars, cli­mate change is plac­ing addi­tion­al demands on the pow­er grid:

“Last win­ter was extreme­ly warm in Nor­way, and the snow began to melt at a time when tem­per­a­tures nor­mal­ly hov­er around minus 20 degrees Cel­sius. All reg­u­la­tors and trans­form­ers are designed for win­ter con­di­tions, but sud­den­ly there was decen­tral­ized, unreg­u­lat­ed hydropow­er that was not planned for. This definite­ly caus­es a lot of prob­lems for dis­tri­b­u­tion net­work oper­a­tors,” explains Kris­tensen. As such events become more fre­quent, there are increas­ing­ly cas­es where Magtech has to sup­ply its volt­age reg­u­la­tors even fol­low­ing con­ven­tion­al grid expan­sion, because the grid expan­sion alone was not suf­fi­cient to solve the volt­age prob­lems.  

More capacity for Lofoten 

Until now, Magtech has relied on ECOTAP^® VPD^® for its MV reg­u­la­tors. Last year, the man­u­fac­tur­er even received a Nor­we­gian inno­va­tion award for its device con­cept. How­ev­er, there are increas­ing requests from cus­tomers who require more pow­er­ful devices. One such cus­tomer is the ener­gy sup­pli­er ELMEA, which sup­plies elec­tric­i­ty to the Lofoten Islands, a remote arch­i­pel­ago in north­ern Nor­way. It need­ed an MV reg­u­la­tor with 10 MVA. How­ev­er, with the ECOTAP^® VPD^® and its max­i­mum cur­rent of 100 amps, the lim­it is already reached at a load lim­it of 3.3 MVA when oper­at­ing at 22 kV. 

The new VACUTAP^® VI opens up com­plete­ly new pos­si­bil­i­ties here. “We had to adapt our design because the VACUTAP® VI is actu­al­ly designed for pow­er trans­form­ers and not for appli­ca­tions like ours. But in the end, instal­la­tion is still quite sim­ple,” says Kris­tensen. Although the MV reg­u­la­tor with the new tap chang­er is now longer, it is still sig­nifi­cant­ly more com­pact than devices from oth­er man­u­fac­tur­ers in this pow­er class. “I think we have a real­ly good prod­uct here that is also very cost‑e«ective,” says Kris­tensen.  

Since the ECOTAP^® VPD^® also shares the oil sup­ply with the wind­ings in the tank, switch­ing to the new tap chang­er was not a major change. The most impor­tant aspect is that vac­u­um tech­nol­o­gy allows up to 300,000 switch­ing oper­a­tions with­out main­te­nance, which is espe­cial­ly impor­tant for Magtech since its devices are used in very remote regions. “Our cus­tomers are very satisfied with the ECOTAP^® VPD^® and I expect it to be the same with the VACUTAP^® VI,” says Kris­tensen. In any case, he has no real choice–Magtech’s cus­tomers want noth­ing oth­er than MR tech­nol­o­gy. “I am delight­ed that the fact that we can build MV con­trollers of up to 10 MVA has opened up a new mar­ket for us, espe­cial­ly in the Nordic coun­tries.”