Regavolt and Portavolt Variable Transformers

Regavolt logo

Regavolt® variable transformers are auto-wound variable transformers, incorporating a moving brush which can travel across the surface of an exposed part of the winding.  This acts as a variable tapping over the winding and allows the output to be adjusted from 0–100% and/or 0-113%, depending on the Regavolt® model. The 0-113% option is particularly useful in electrical, electronics, test and development workshops, and for testing products to ensure they meet British Standards.

The Regavolt Range

The latest Regavolt® range is the latest development in the long history of the brand.  It is now a registered trademark of The Allendale Group Limited, who are continuing the long tradition started when Claude Lyons introduced the variable transformer to the United Kingdom in 1933.

Regavolt® offers an extensive choice of ratings available in both single and three phase, with options on knobs, dials, motor drives and cases readily available.

In addition to our standard Regavolt® ranges, we also supply auto-wound variable transformers manufactured to meet customers’ bespoke requirements.

Regavolt Variable Transformers
Portavolt Logo

The Portavolt® 715 Series of enclosed variable auto-transformers are world renowned for their robust construction and reliable performance. Incorporating the latest generation of Claude Lyons 715 Regavolt® variable transformers and manufactured to the latest standards, they meet the requirements for a wide range of industries including laboratory, manufacturing, test, and educational applications.  The units are available with various metering and input/output connection options, and are fitted with shrouded 4mm test sockets for external meter connection.

  • Robust & rugged construction
  • Air cooled via natural convection
  • input and output via IEC 320 connectors
  • Bench or wall-mountable
  • High Efficiency
  • Thermal overload cut-out
  • Continuously variable output 0 to 115%
  • No harmonic generation
  • Carry handle for easy handling
  • No waveform distortion
  • 4mm shrouded outlet test sockets
  • Manufactured to meet BS EN 61558-2-14

Manufactured in the UK

Our Portavolts carry the official Made in Britain badge

Made in Britain logo
Portavolt Enclosed Variable Transformer
Portavolt production

Applications include:

Test and development

Lamp intensity control

Heating load control

Motor speed control

Order online

Our standard ranges of Regavolt and Portavolt systems can be ordered online at


Worldwide shipping

Spares available

Bespoke design service

Secure online ordering

Clients we have worked with: