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Bernard Bonnefond S.A.S.

7 Allée Mathieu Murgue Terrenoire, 42100 Saint-Étienne
Telephone +33 477 953009
Fax +33 477 957806

Hall map

glasstec 2018 hall map (Hall 13): stand A73

Fairground map

glasstec 2018 fairground map: Hall 13

Our range of products

Product categories

  • 01  Glass production/Production Technology
  • 01.04  Glass melting technology
  • 01.04.08  Electrically heated systems

Electrically heated systems

  • 01  Glass production/Production Technology
  • 01.09  Kiln technology
  • 01.09.05  Pre-heating furnaces

Pre-heating furnaces

  • 05  Measurement, testing, control technology and software
  • 05.03  Host computer systems, IT, Communication and Security Technology
  • 05.03.04  Other control systems

Other control systems

Our products

Product category: Electrically heated systems, Pre-heating furnaces, Other control systems


On load Variable Voltage Transformer - from 200 to 30,000 kVA
Technical Performances
LV or HV primary voltage
Galvanic Insulation between primary and secondary windings
Linear, on load voltage variation
Friendly simplified interface with supervisiory systems
100 % custom made equipment

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

Magnetic circuit
VARIVOLT is a rotating core transformer.
The magnetic circuit consists of 2 flat bored yokes, and cylindrical rotating cores.
Cores are made of magnetic steel strips radially stacked around a shaft.
The cores are driven in rotation by an external motor. The cores are the only mobile parts.

Galvanic insulation is acheived thanks to separated primary and secondary windings.
The induction and the voltage per turn is constant, resulting in high efficiency and power factor.
HV or LV primary windings are in most cases standard.
LV secondary windings comprise a grooved copper conductor, allowing 0 to 100 % variation of the maximum secondary voltage.

Sliding contact
The sliding contact is made of special copper to facilitate high current transfers.
Helical mouvement of the sliding contact along the winding allows voltage variation without arcing.
The oil filled VARIVOLT minimises corosion of the sliding contacts and guarantees several years of maintenance free use.

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About us

Company details

Bernard Bonnefond was founded in 1925.
Over the last thirty years the company has specialized in developing electro-technical products to better serve its French and foreign customers, including :
Preliminary studies and custom tailoring of each piece of equipment to perfectly match each customer unique specification.
Supply of “turnkey”packages, field installation, start- up, commissioning and operator training.
Technical support to maintenance crews ,as well as engineering and design assistance for new projects.
More than 80 % of BB production is exported

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