The development of cable penetrations in Hungary started in 1987, when a team of researchers designed, patented and type tested the AHA type, 6 kV electrical penetration assembly (EPA). 96 pieces of those EPAs were installed in Paks NPP. They are still in service without any disorder.

VISOLA Ltd was founded by three key research engineers in 1991 and – based on their former experience – undertook the development and manufacturing of further EPAs intended for replacement of obsolete power and I&C penetrations in Paks NPP. The design of the new products was based on application of glass-to-metal sealed penetrations, made by SCHOTT Electronic Packaging GmbH. They were completed by gamma-screening developed by VISOLA Ltd. Since 1996 until 2009 altogether 345 pieces of complete EPAs were delivered to Paks NPP. Those all work still perfectly. No complaint received so far.

In 1997 VISOLA Ltd extended its operation with trade of cables and cable accessories. This field of activity is getting stronger gradually since 2005.

In 2006 VISOLA Ltd started a new development project to elaborate an economic technology for refurbishment of EPAs. The reason was the decision of the Hungarian government to extend the service time of VVER type blocks of Paks NPP which also required a modernization of old I&C EPAs not replaced yet. According to a new concept the original casing tubes with gamma screening should remain in containment walls and only obsolete penetration modules are to be replaced with new ones. VISOLA Ltd developed a family of new penetration modules including epoxy resin insulation. The work was financially supported by an EU and Hungarian government fund, called GVOP project. The new modules with special stainless steel accessories enable the refurbishment of old EPAs on site. The same procedure is used for renovation of aged EPAs in our workshop. Eight pieces of renewed EPAs are in service since 2008.

VISOLA Ltd also developed heavy duty leakage proof cable junction boxes for EPAs, including wall mounted version as well.

VISOLA Ltd demands close quality control and precise quality inspection. Unfortunately appropriate instruments are hard to find in research institutes, universities and laboratories we cooperate with. Consequently, a part of our activity was always devoted to development and production of special test instruments. Those are used both in routine and type test procedures.