Tesar
Cast resin transformers for demanding applications worldwide
Tesar – Expertise in cast resin dry-type transformers
Tesar brings together all global activities in cast resin dry-type transformers and instrument transformers within the R&S Group. With locations in Italy (Tesar Italia), Poland (Tesar Polska) and the United Arab Emirates (Tesar Gulf), the group offers a consistent portfolio of cast resin transformers and current and voltage transformers for medium-voltage applications – from standard distribution networks to complex industrial and infrastructure projects.
As one of Europe’s pioneers in cast resin technology, Tesar has been developing dry-type transformers since 1979 with high fire safety classes, low maintenance requirements and excellent electrical performance. More than 100,000 Tesar transformers installed worldwide are a reference for technical reliability, efficiency and long service life.
Tesar is active in European and international standardization committees and works closely with utilities, EPCs, planners and operators. Applications range from renewable energies (wind, solar, BESS) and data centers, tunnels, hospitals and airports to rail power supply, near-offshore projects and critical infrastructure.
Tesar’s strengths at a glance:
Cast resin expertise since 1979
Deep know-how in design, casting processes, resin systems and aging behavior of dry-type transformers.
Three production sites – one quality standard
Development and manufacturing in Italy, Poland and the UAE with harmonized standards, certified management systems (including ISO 9001, 14001, 45001) and state-of-the-art test laboratories.
Ecodesign & energy efficiency
Loss-optimized designs in line with EU Ecodesign requirements and international standards; focus on low total cost of ownership (TCO) and CO₂ reduction.
Broad range of applications
Solutions for distribution networks, industry, infrastructure, data centers, ports, renewable energy projects, rail, e-mobility, storage applications and special projects in demanding climate zones.
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Every casting a promise of quality
“When casting our windings, every second counts – our experience makes the difference in safety and durability.”
Mr. Bianchini, TRP Department · Tesar Italia
Frequently asked questions
Tesar in general
Who is Tesar?
Tesar is the R&S Group's brand for cast resin transformers (dry-type transformers) and current and voltage transformers, operating regionally as Tesar Italia, Tesar UAE and Tesar Polska. Tesar transformers are used wherever liquid-filled transformers are not wanted or environmental or fire protection requirements apply.
What is a cast resin transformer?
A cast resin transformer is a dry-type transformer whose windings are encapsulated in epoxy resin instead of being immersed in oil. This largely eliminates the fire risk posed by insulating oil and allows installation at the load centre – for example directly inside buildings.
What are the advantages of a cast resin transformer over an oil-immersed transformer?
Cast resin transformers have a low fire risk and low toxic gas emissions in the event of fire, essentially require only a visual inspection for maintenance and, thanks to the low fire risk, can be installed at the load centre. Oil-immersed transformers, on the other hand, are often more compact and more cost-effective in many standard applications.
Do Tesar transformers comply with the EU Ecodesign directive?
Yes. Tesar transformers meet the requirements of the EU Ecodesign Regulation (EU) No 548/2014 Tier 1 and 2, the follow-up Regulation (EU) 2019/1783 Tier 2 and IEC 60076-11:2018-10.
What is special about Tesar's EcoPlus2030 series?
EcoPlus2030 is a transformer series developed by Tesar engineers with significantly lower CO₂ emissions and losses than standard Ecodesign Tier 2 transformers. It is aligned with the sustainability goals of the UN 2030 Agenda and achieves the CO₂ reduction both through lower no-load losses and through the use of grain-oriented electrical steel (GOES).
Are Tesar transformers suitable for renewable energy applications?
Yes. Tesar transformers are used in power distribution and power generation, including photovoltaic, wind and hydropower plants, for which special designs are available.
Does Tesar also manufacture current and voltage transformers?
Yes, current and voltage transformers for medium-voltage applications are part of the portfolio, especially through Tesar Polska. The range comprises four current transformer designs (CEI-UNEL, block, DIN, toroidal) and five voltage transformer designs (CEI-UNEL 2-/1-pole, DIN 2-/1-pole, 1-pole with fuse holder) with insulation levels up to 36 kV.
Tesar Italia
What does Tesar Italia offer?
Tesar Italia manufactures cast resin transformers up to 25 MVA and 52 kV, including special designs for data centres, ports, railways, tunnels and critical infrastructure. It also offers solutions for renewable energies (wind, solar/PV, BESS) as well as current and voltage transformers for medium-voltage applications.
Which industries is Tesar Italia particularly specialised in?
Tesar Italia has a strong focus on demanding infrastructure projects – such as ports, railways and tunnels – as well as on data centres and critical infrastructure, where safety and reliability requirements are high. Applications on board ships are not part of the portfolio; in ports, the focus is on shore-side infrastructure solutions.
Does Tesar Italia also supply current and voltage transformers?
Yes. Tesar Italia offers current and voltage transformers for medium-voltage applications to complement its transformer portfolio.
Tesar UAE
What does Tesar UAE offer?
Tesar UAE (formerly Tesar Gulf) manufactures cast resin transformers up to 3,150 kVA and 33 kV for medium-voltage networks, data centres and other industrial and infrastructure projects in the Gulf region.
Which market is Tesar UAE responsible for?
Tesar UAE covers the demand for cast resin transformers in the Middle East and the Gulf region, with a focus on medium-voltage networks and data centre infrastructure.
What is the difference between Tesar UAE and Tesar Italia?
Tesar UAE focuses on medium-voltage applications up to 3,150 kVA / 33 kV and on the Gulf states, whereas Tesar Italia covers a much higher power and voltage range of up to 25 MVA / 52 kV as well as additional special applications (railways, ports, tunnels) and operates worldwide.
Tesar Polska
Who is Tesar Polska and where is it located?
Tesar Polska is the Central European production site of the Tesar brand, based in Niepołomice in the industrial area of Kraków, Poland. Since 2013, the site has been developing and manufacturing cast resin dry-type transformers as well as current and voltage transformers for medium-voltage applications.
What role does Tesar Polska play within the Tesar group?
Tesar Polska complements the Italian parent plant with a modern manufacturing base in Central Europe; its central location near Kraków ensures optimal supply to the markets in Northern and Eastern Europe as well as the German market.
What exactly does Tesar Polska offer?
Tesar Polska manufactures cast resin dry-type transformers for medium-voltage applications up to 3,150 kVA and 24 kV for distribution networks, industry, infrastructure and renewable energies, plus project-specific variants for data centres and other sensitive building services, as well as current and voltage transformers for medium-voltage applications.
Does Tesar Polska also offer service and technical support?
Yes. Tesar Polska provides technical support and project-specific assistance from design and specification through support with standards, grid and plant requirements to commissioning, complemented by diagnostic, modernisation and service offerings over the entire life cycle – for utilities, industry, infrastructure operators and EPC partners throughout Europe.