100 Years
100 Years
Deep Dive

100 Years Original. 
100 Years First.

From the first on-load switching operation to the new vacuum generation – developed together with grid operators and transformer manufacturers.

Since 1926, we have been setting the pace for stable power grids: from the very first resistor-type on-load tap-changer to the latest VACUTAP® generation. At MR, “being first” is not a label — it is a mindset: the original that sets standards and keeps redefining them.

What drives us? Partnership. Solutions at MR emerge together with grid operators and transformer manufacturers — based on their needs, engineered with our expertise, for reliable grids. Mechanical and digital. As stand‑alone products or complete system solutions. For the global market and for specialized applications. For the all‑electric society.

1929
First On‑Load Switching – Type C

Dr. Jansen’s new resistor principle made on-load switching possible for the very first time. The first prototype from 1929 marked the beginning of modern voltage regulation.

  • 14 operating positions
  • Selector principle
  • Max. 1.1 kV
  • Three patents (1928/1929)

1933
Technical Leap in Tube Design – Type C

For the first time, Type C combined tap-changer and selector in a protected tubular housing — compact, weatherproof, and service-friendly.

  • Rotating contact system
  • Approx. 8,770 units
  • Voltage up to 66 kV

1938
More Safety Through Separate Switching Mechanics – Type D

Type D introduced separate mechanical assemblies – a milestone on the way to higher operational safety and performance.

  • Rotating contact system
  • Small series from 1943
  • Up to 230 kV
  • More than 13,000 units produced

1973
The Global Market Changer – OILTAP® M

OILTAP® M was the first MR tap-changer to be manufactured in real series production – compact, robust, and internationally successful.

  • GRP oil vessel instead of hard paper
  • High production volumes
  • Mechanical optimizations

1974
Seven at One Stroke – First Semiconductor Tap-Changer

For extreme switching frequencies, MR developed a hybrid tap-changer with external power electronics.

  • Up to 300,000 operations per year
  • Maintenance-free up to 1,000,000 operations
  • External semiconductor technology
  • 7 units produced

1990
Vacuum Meets Reactor Design – First Reactor Tap-Changer VACUTAP® RMV

With the VACUTAP® RMV, MR entered reactor tap-changer technology – for the first time with reactor bridging impedance.

  • More than 12,000 units in service
  • Maintenance-free up to 500,000 operations
  • Oil heating system for arctic region

1995
Safe Without Oil – Vacuum Tap-Changer for Dry-Type Transformers – VACUTAP® VT®

VACUTAP® VT® was one of the world’s first vacuum tap-changers for cast resin and dry-type transformers.

  • Service life up to 800,000 operations
  • Spring energy storage integrated into the selector
  • Modular “one switch per limb” principle

2000
The Vacuum Standard in Oil Tanks – VACUTAP® VV®

VACUTAP® VV® brought vacuum technology into oil-filled transformers – less wear, longer service life, and minimal maintenance.

  • Selector + diverter switch in a single oil vessel
  • More than 12,000 units
  • Maintenance-free up to 300,000 operations

2012
Regulating Distribution Grids – GRIDCON® iTAP®

The first series solution for regulated distribution transformers – modular, precise, robust.

  • Vacuum switching technology
  • Service life up to 700,000 operations
  • Freely positionable in the winding

2014
Fully Electronic – The First Full Semiconductor Tap-Changer – Power X12

With Power X12, MR demonstrated that fully electronic tap-changers are technically possible – a look into the future.

  • Developed for arc furnace transformers
  • Complete thyristor technology
  • Concept study, not transferred to serial production

2015
Digitalization at the Transformer Head – TAPMOTION® TD ISM®

The first motor drive with integrated monitoring laid the foundation for intelligent transformers.

  • ISM® technology
  • Data basis for monitoring and control
  • Control cabinet–linked functions

2016
Electronic, Efficient, Compact – ECOTAP® VPD®

ECOTAP® VPD® is the world’s first electronically controlled resistor-type tap-changer for distribution transformers.

  • Local voltage control for greater grid flexibility
  • More hosting capacity without reinforcement
  • Enables cost‑efficient, future‑ready grids

2018
The Digital Breakthrough – ETOS®

With ETOS®, the first open operating system for power transformers emerged – networked, modular, future-ready.

  • Real-time monitoring of all components
  • Open to third-party integration
  • Complete sensor and control integration

2025
The New Vacuum Generation – VACUTAP® VI

VACUTAP® VI opens a new class of high-performance vacuum switching technology – more compact, more efficient, more sustainable.

  • First integrated type tap-changer
  • Up to 13% reduced tap changer size
  • Higher power density

Less. Better. VACUTAP® VI

A new class of high-performance vacuum switching technology – more compact, more efficient, more sustainable.

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