On-load tap-changers (OLTC) for regulating transformers

For about 80 years now we have been manufacturing on-load tap-changers and we still keep coming up with epoch-making innovations.

The VACUTAP® series, just one example, with its vacuum switching technology for on-load tap-changers in oil-immersed and dry-type transformers. This is now the most common form of technology in reactor-type tap-changers and has revolutionised resistor-type tap-changers. We have been using this technology since the 1980´s and are continuously refining it thus bringing you advantages such as no service requirements before 150,000 to 500,000 switching operations, drastically reduced running costs for the whole physical life, increased availability of the transformer, no oil carbonization, no replacement of contacts and no oil filter systems - to mention but a few of the many benefits.

To a great extent the OILTAP® - program with its conventional tap-changer technology (arcing contacts in oil) and already well-known to you, is still available as an alternative.

VACUTAP® VM® VV® VR® VT® AVT RMV-A RMV-II
Max. rated through-current (1-phase) 1500 A 400 A 1,600 respectively 2,600 A * 500 A - - -
Max. rated through-current (3-phase) 650 A 600 A 1,300 A 500 A 170 A 1320 A 1500 /
2000 /
2500 A
Max. rated step voltage 3300 V 2000 V 4000 V 900 V 500 V 300 V 2000 V
Max. rated switching capacity (1- / 3-phase) 3500 / 1625 kVA 700 kVA 3000 kVA 250 kVA 75 kVA    
Highest voltage for equipment Um 72,5 - 300 kV 40 - 145 kV 72,5 - 362 kV 40,5 kV 11,5 kV 15 kV 70 kV
Application at neutral point (three-phase) or at any selectable winding position:
Operating positions without change-over selector max. 22 max. 12 max. 18 max. 9 max. 9 max. 17 max. 17
Operating positions with change-over selector max. 35 max. 23 max. 35     max. 33 max. 33
* with enforced current splitting of the transformer winding


OILTAP® V MS M R G RM
Max. rated through-current (1- / 3-phase) 200 / 400 A 300 A 1500 / 600 A 3000 /
1200 A
2000 A 1500 / 600 A
Max. rated step voltage 1500 V 3300 V 3300 V 4000 V 5000 V 4000 V
Max. rated switching capacity (1- / 3-phase 525 kVA 1000 kVA 3500 kVA 6000 / 3000 kVA 5000 kVA 4280 / 2400 kVA
Highest voltage for equipment Um 40 - 123 kV 72,5 - 245 kV 72,5 - 300 kV 72,5 - 362 kV 72,5 - 362 kV 72,5 - 300 kV
Application at neutral point (three-phase) or at any selectable winding position:
Operating positions without change-over selector max. 14 max. 14 max. 22 max. 18 max. 18 max. 18
Operating positions with change-over selector max. 27 max. 27 max. 35 max. 35 max. 35 max. 35