ROTAVOLT Variable Auto Transformers

Rotavolt Variable Auto-Transformers provide a continuous linear regulation of AC voltage, with high efficiency and negligible waveform distortion. It offers a precise and effective method of controlling current, light, heat, motor speed and any parameter with a voltage factor.

Single and three phase models come in 9 frame sizes and rating up to 60kVA. Motorised versions available for remote or automatic operation.

ROTAVOLT Ratings and Dimensions


  • 9 frame sizes and ratings up to 60kVA.
  • Single and three phase models.
  • Ideal for high-speed servo applications.
  • Multi ganged units available.
  • Motorised versions available for remote or automatic operation.
  • Maximum input voltage +6% of nominal, i.e. 240V models are continuously rated at 254V.
  • Output Voltage continuously variable from 0 - 115% of input voltage.
  • Low torque operation, ideal for multi ganged units.
  • Load Power Factor: Any
  • Waveform distortion negligible.
  • Rated current: May be exceeded by 20% on parts of the track. Performance curves are available upon request.
  • Quality Management System. Assessed and approved to ISO 9001:2000
  • CE Conformity Conforms to the requirements of council directive 89/336/EEC EMC (Valid to Oct 2009) & 2004/108 EEC emissions / immunity and directive 2006/95/EC, (Formally 73.23.EEC) Low voltage directive.
  • Surge rating
Units up to 2.5A (CO1 &CO2)
6 times for 1 sec
3 times for 1 min
2 times for 5 mins

 All larger models
10 times for 1 sec
3 times 1 min
2 times 5 mins
  • Rugged construction for safe portable use and to eliminate transit damage.
  • Enclosure: All models supplied in open form, ventilated covers to IP20 BS60529 can be provided if required.
  • Mounting: All models can be surface or panel mounted.
  • Fixing: Three fixing points equally spaced by 120 deg. Alternate fixings provided on some models.