Still Going Strong

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From the drawing board to the grid

Those were the days! When Wolf­gang Albrecht joined MR’s devel­op­ment depart­ment as an engi­neer back in 1987, on-load tap-chang­ers were still being designed on a draw­ing board, as you can see in this image of his col­league Leo Pillmeier. This was also true for the ini­tial drafts of the VACUTAP® VV®, which was designed by a devel­op­ment team led by Albrecht.

“When it was launched on the mar­ket in 2000, it was the world’s first high-speed resis­tor-type tap-chang­er involv­ing vac­u­um tech­nol­o­gy and insu­lat­ing oil.” Of course, draw­ing boards have long since been replaced with 3D CAD sys­tems at MR, but apart from a few small tech­ni­cal changes, the VACUTAP® VV® still oper­ates based on the same con­cept.

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The starting point

In con­ven­tion­al tap chang­ers, an elec­tric arc con­t­a­m­i­nates the insu­lat­ing oil when switch­ing takes place, mean­ing that the oil reg­u­lar­ly needs chang­ing. In appli­ca­tions with hun­dreds of thou­sands of switch­ing oper­a­tions, that’s quite often! As envi­ron­men­tal and cost con­cerns became more promi­nent among ener­gy sup­pli­ers, the call for an alter­na­tive low-main­te­nance solu­tion grew loud­er.

Pioneering work

MR moved into vac­u­um-switch­ing tech­nol­o­gy at the end of the 1980s when it pur­chased the reac­tor-type tap-chang­er divi­sion of West­ing­house Elec­tric Cor­po­ra­tion. How­ev­er, the tech­nol­o­gy remained a side­line for a long time and only real­ly caught on with the VACUTAP® VV®.

The solution

The elec­tric arc can­not cause dam­age in vac­u­um inter­rupters, so there’s no need to change the oil. What’s more, this switch­ing tech­nol­o­gy enables alter­na­tive, envi­ron­men­tal­ly friend­ly insu­lat­ing flu­ids to be used. Devel­op­ing the VACUTAP® VV® was tricky, recalls Albrecht: “The biggest chal­lenge was to adapt the spring ener­gy accu­mu­la­tors for switch­ing. The vac­u­um forces of the six vac­u­um inter­rupters mean that much high­er dri­ve torques are required when switch­ing”.“

2,525 operators

world­wide are using the vac­u­um on-load tap-chang­er. It is oper­at­ing in trans­form­ers from 399 dif­fer­ent man­u­fac­tur­ers.

27,123 VACUTAP® VV®

units have been sold since the mar­ket launch. Ini­tial­ly, orders grew slow­ly but more and more grid oper­a­tors and man­u­fac­tur­ers soon rec­og­nized the ben­e­fits.

switching operations

(at least) can be com­plet­ed by today’s VACUTAP® VV® before a ser­vice is due, with just inter­im main­te­nance per­formed after 300,000 switch­ing oper­a­tions. With the first VV, the main­te­nance inter­val was just 150,000 switch­ing oper­a­tions.

— 25 (40) to + 120 °C

The tap chang­er is approved for this oil oper­at­ing tem­per­a­ture range. At sub-zero tem­per­a­tures, the oil is very vis­cous, while at high tem­per­a­tures, it is run­ny. Despite this, the switch­ing process always has to work reli­ably in the same way.

40 bis 145 Kilovolt

The VACUTAP® VV® can be designed for this volt­age range. Depend­ing on the oper­at­ing volt­age, the tap chang­er is between 1.80 and 2.40 meters in height.

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More information

Want to know more about vac­u­um tech­nol­o­gy at MR?
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