Tesar of Italy prides itself in designing and manufacturing cast-resin transformers for distribution and for special applications such as starting of motors, rectifiers, induction ovens and traction.

“Reliability and safety features make Tesar transformers   specially suitable for use in environments with fire risk or in tough climatic conditions and places such as offshore platforms, refineries, windmills and docks.
The transformers have high technological content and high reliability and are environmentally friendly, a Tesar spokesman says.
Tesar transformers come with a rated power up to 12 MVA and voltage up to 36 kV and the company claims it has installed some 35,000 of them over more than 20 years since it started operating.
Listing the advantages of Tesar transformers, it says they bring savings in installation as the civil work involved is simple and cheap while the compact dimensions of the product reduce the installation area.
“The possibility of installation near the load reduces losses in the connection cables,” it says, adding that the low losses in magnetic core and in the windings give high operational economy.
“Tesar cast resin transformers are designed for withstanding the heaviest ambient and climatic conditions, so preventive maintenance is reduced to a simple visual check and connection tightening.
“The resin as well as the insulating materials gives Tesar transformers high self-extinguishing characteristics as well as allowing low emission of gases both for classes F0 and F1.”
It adds that since the cooling is only through natural air no flammable and polluting fluids are necessary.
Other striking features of the transformers are their low noise level, their high overloading within the IEC905 standard and the possibility of power increase, as much as 40 per cent, using fan-forced systems.
The transformers are also free from partial discharge and are designed for operating at lower temperatures than the ones allowed by the insulating materials used.
“High-technology processes in the manufacturing of he windings give the products high reliability,” it says.
Tesar transformers are in conformity with the EEC directive 89/336 as proved by the tests carried out by the authorised laboratories.
The transformers are also in conformity to standards IEC 726, Cenelec HD 464 Si/A3.
In the environmental class, the EO transformers are suitable for use in clean and dry environments; the EI is suitable in the presence of occasional condensation and low pollution and the E2 in highly polluted environments and in the presence of substantial condensation.
In the climatic class, the C1 is suitable for use with ambient temperature up to  –5 deg C and it can be delivered and stocked with an ambient temperature up to –25 deg C.
As C2 the transformer is suitable for being stocked and used with ambient temperature up to –25 deg C.
In terms of behaviour in fire, the F0 transformer is suitable for use in the environments with fire risks. The F1 is a self-extinguishing transformer, which does not give out toxic substances and fumes.
The transformers’ LV windings are realised using single aluminium sheets with pre-impregnated class F insulated materials. Then the coils are subjected to a polymerisation thermal treatment for obtaining the finished product. The special constructive geometry allows, other than the extraordinary withstanding to electrodynamic stresses, minimisation of the stray flux for electromagnetic compatibility purposes.
Medium voltage windings are made of aluminium (tape or wire). The assembling technique and the materials used allow the creation of a product practically free from internal mechanical stresses. During the casing process, each parameter is electronically monitored in order to obtain the complete homogeneity of resin dielectric features.