Still Going Strong

For 20 years, the VACUTAP® VV® has been helping customers across the globe to operate their trans­formers with virtu­ally no main­te­nance. The story of a best­seller.

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.

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”.“


The very first tap changer

The first VACUTAP® VV® to leave the produc­tion plant in Regens­burg set off on a long journey. Its desti­na­tion was Kuwait City in the emirate of the same name on the Arabian Penin­sula. The tap changer has reli­ably been carrying out its work inside a Hungarian trans­former at a primary substa­tion in the Yarmouk district of the city since May 2000. And it’s still going strong. To this day, it hasn’t expe­ri­enced a single failure. And a good job too! Summer temper­a­tures in this desert city climb to 50 degrees Celsius, making air-condi­tioning an absolute neces­sity for its resi­dents.


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.

More infor­ma­tion

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