Variable voltage transformer in charge from 200 kVA to 30 MVA

Technical Performances

  • LV or HV primary voltage
  • Galvanic Insulation between primary and secondary windings
  • Linear, on load voltage variation
  • NoDCComponent
  • Friendly simplified interface with supervisiory systems

Technical Performances

  • Efficiency higher than 98 %
  • High power factor
  • No addition of harmonics to the mains
  • Power delivered always adapted to the load
  • Reduced sizes

Control panel

BERNARD ENGINEERING control panels are designed and manufactured to ensure the control of VARIVOLT and IVR from the primary breaker to the secondary load. BERNARD ENGINEERING supplies 2 solutions : MICVAR PANEL with PLC and BB CABINET without PLC

MICVAR control panel

All digital and analog inputs are wired to a PCL which provides the following functions :

  • Safeties with relays redundancy
  • Sliding contacts position
  • Automatic control of power, current or voltage
  • Primary breaker (control), current or voltage
  • Reading and management of voltage, current, oil temperature signals
  • Numeric communication with remote keybord or supervisor
  • Emergency keyboard on panel door, to allow VARIVOLT control without PLC

A colour touchscreen can be associated to the MICVAR

BB control cubicle

Control is based on relays without PLC nor numeric communications. The main functions are :

Safeties (Temperature, oil, gas, overcurrent) & Primary breaker control

A remote keyboard with pushbuttons light and a numeric measurement display can be associated to the BB cabinet.

Other products

Induction voltage regulator

The induction regulator is a CONTINUOUS REGULATOR LOADING the voltage or the current. Its design is close to that of an asynchronous motor with a wound rotor. It operates as a rotating field transformer in a power range from 30 kVA to 3,000 kVA.

Like an asynchronous motor with a wound rotor, it has a rotor and a stator. The rotation of + or - 180 ° of the rotor allows the variation of electric voltage. There is no moving contact and the simple design ensures high reliability.

High intensity transformer

The high intensity transformer can run until 50,000 Amperes and can be associated with a VARIVOLT in case of intensity of more than 10,000 Amperes. Each core leg is composed of several alternated elementary transformers. The high intensity transformer can also be used on trial platforms.

Specific studies on request.

Fix transformer

  • Up to 35 kV
  • For short circuit test

Rectifier set

Example in the photos: Variable power supply 30,000 A - DC, from a 20,000V - 50 Hz network

The rectifier set is an element allowing to transform an alternative tension into continuous tension. This one is constituted by one or several bridges of diodes which we also call " bridge of Graetz ".

In our applications, the rectifier set is generally placed in the downstream of a Varivolt ® (transformer with variable voltage in load), which allows us to obtain a variable continuous supply.

This supply is generally low-voltage but can reach intensities of continuous 30.000 A.

Coils / Self / Reactors

1 – Fix Reactor

without magnetic circuit or with air gap into the magnetic circuit.

2 – Variable Reactor

  • A plunging magnetic core changes the reactor.
  • Where from a fall of potential

3 – Saturable core reactor

An iron-core reactor having an additional control winding carrying direct current whose value is adjusted to change the degree of saturation of the core.


  • arc furnaces
  • glass or steel melting


  • Simple
  • Robust


Embedded solution in container


BERNARD ENGINEERING has developped a solution with VARIVOLT fixed in one container, 20’ or 40’ with primary protection and control command, in order to facilitate the installation, and allow the transport from site to site.

Application : Soil treatment, hydrogen production...


All in one container

It includes the VARIVOLT, the primary protection cells, one or more auxiliary transformers, the control command, the retention tank. Just connect to the network and the application.

Turnkey installation

Bernard Engineering supplies engineering and services for variable electrical power systems AC or DC. Our expertise ranges from design to start-up assistance worldwide for glass, steel, electrochemical industry and platform of electrical tests.


  • General outlay of the installation
  • Safety for people and equipement
  • Planning
  • Preliminary studies


  • Equipment specification
  • Implementation
  • Power distribution
  • Electrical schemes
  • Complete set of drawings


  • Technical definition for subcontracting
  • Selection of suppliers
  • Monitoring


  • Regular inspection of construction
  • Test before energizing
  • Industrial test
  • Staf training

After sales service

Overhaul - Repair - Maintenance of transformers in our workshops in Saint Etienne or directly on site for overseas customers.

Qualified staff.

Désolé, nos réalisations ne sont actuellement pas disponibles pour ce produit.