Certified quality UNI EN ISO 9001

ottavi impianti stripe


ottavi resina

General information
Our transformers are designed and manufactured according to CEI 14-8 and IEC EN 60076 and can be equipped with optional accessories, to better adapt to the specific needs of Customer. Our standard types of resin transformers can have primary voltage up to 30 kV and capacities from 100 to 3150 kVA or designed to customer specifications on request.

Magnetic core
The magnetic core is made of laminations of grain oriented, cold rolled, low loss and isolated superficially so as to minimize the eddy current losses. The coupling between columns and yokes is made with joints intercalated at 45 ° in order to reduce both load losses both the noise of the transformer. The core is treated with appropriate non-hygroscopic paint to protect the surfaces and various cut points from oxidation and corrosion.

The windings of MT are manufactured using aluminum tape UNI 4507puro, title 99.9% interavvolto with appropriate dielectric insulating base of the reinforcing glass fiber. After commissioning the mold and the necessary vacuum drying the windings are embedded, always under vacuum, with epoxy resin. The uniformity of thickness inside and outside of the resin ensures resistenzaalle dielectric stresses. On the front jacks are provided for adjusting the voltage, normally equal to value ± 2 x 2.5%. The windings are made of BT with UNI 4507 aluminum plate with a height equal to that of the entire column so as to obtain a compactness such as to form a single cylinder resistant to any axial and radial stress resulting from short-circuit phenomena. In the windings is engaged a new insulating fashion to avoid absorption of moisture, therefore suitable to operate both in environments with intense tropical or marine pollution. The class of thermal insulation used correspond to the class F of the CEI 14-8 and IEC EN 60076, which admits temperature rise of 100 K of ambient up to 40 ° C. On special request we design and manufacture transformers with reduced losses and executions special, able to operate in particular environments for conditions and / or temperature.

Characteristics of the resin
The resin encapsulation of the medium voltage windings is exclusively type mineral filler in epoxy with silica and alumina treated in an autoclave under vacuum in such a way that obtain a perfect degassing in relation to the presence of air or any gas. The epoxy system is class F has passed the certification tests E2, C2, F1, as defined by IEC EN 60076, and is characterized by dielectric and mechanical properties such as able to withstand the various stresses to which it will be subjected during use.

The transformers are manufactured following a system of Quality Assurance compliant UNI EN ISO 9001: 2008. The tests acceptance standards (defined by the CEI 14-8 and IEC EN 60076) are described below:

• measurement of the resistance of the windings
• measurement of the ratio of transformation and control of the polarities and connections
• isolation test with induced voltage
• measurement of short-circuit and losses due to the load
• extent of the losses and the load current
• partial discharge measurements

All our transformers are equipped with amenities such as:

cart with casters;
ground terminals;
base for adjusting the MV side (± 2 x 2.5%);
PT100 temperature sensors;

and can also be equipped with:
electronic temperature control (type T154);

bars forced ventilation (tangential fans) metal box containing

1) Reduction of environmental impact

Improved safety:
Through the use of an epoxy resin of high quality, resin transformers minimize the environmental impact and comply with international environmental standards IEC 60076-11 (HDL 464 S1 1998). They are constructed entirely of materials flame retardant and self-extinguishing in order to obtain inflammability close to zero (through self-extinguishing water vapor given off from the resin in case of pyrolysis) and almost no emission of toxic gases and opaque smoke (fire resistance classification F1).

Absence of cooling fluids:
Thanks to the absence of cooling fluids, resin transformers do not present risks of pollution and drastically reduce its contribution under fire than transformers insulated bath of mineral oil.

Materials recovery at end of life:
The resin transformers can be considered the most environmentally friendly type of construction, which is particularly important when you need to dispose the machine that has exhausted its life cycle work. For disposal, the resin is considered inert material and the primary and secondary windings, as well as the core and the parts of carpentry, can be easily recycled.

2) Simplify installation

Reduction of dimensions:
resin transformers have dimensions below, which are constituted with a reduction of about 16% relatively to the size and 10% relative to the weight.

Reduction of construction works of pose:
resin transformers do not require building works, instead requests for oil transformers, such as collection wells (if the oil in the transformer is greater than or equal to 500kg), grilles off and barriers separation fire resistant, to prevent the spread of fire and the shedding of insulating liquids. For resin transformers, being class F1, is not required to measure separation with fire barriers.

Installation inside buildings:
Thanks to the reduction of expensive construction work, the greater safety (low risk of fire) and the absence of cooling fluids, resin transformers can be installed within buildings, also in proximity to places frequented by people. It 'so can contain spaces and installation costs.
Additionally transformers can be installed inside the building closest to the loads, with the advantage of saving in the costs of connection and reduce losses in the supply line.

3) Flexibility in use

Major overload:
The resin transformers, using air as the cooling medium and taking more time to reach the temperature of the system, are more than overloadable transformers insulating liquid and are therefore particularly suitable for powering loads with frequent current peaks. The transformers can be overloaded, as long as the temperature rise in the windings not remain above the permissible values for long periods of time.

Less maintenance:
The resin transformers are characterized by lower maintenance costs because only need to be inspected regularly for the absence of accumulation of dust and dirt in general. The oil transformers should be supervised to ensure the level of the insulating liquid and verify that this retains unchanged its dielectric properties.

ottavi resina

Improved safety
Absence of cooling fluids
Materials recovery at end of life
Reduction of dimensions
Reduction of construction works of pose
Installation inside buildings
Major overload
Less maintenance


ottavi ecosystem

OTTAVI srl, a leader in the production and marketing of transformers, has focused its efforts to the study and implementation a line of transformers entirely dedicated to the sector of the energies renewable energy and energy efficiency, resulting in capitalization economic context of specific applications.

The new line of trasformators LINEA ECOSYSTEM was therefore entirely studied, designed and developed with the intention to create a new standard conceptual and material within which to place the transformers of the latest generation according to increasingly specific needs of the client, representing the fundamental component of the electrical plants.

The objectives pursued and achieved, are to provide a transformer with the following characteristics:

• low losses
• maximum efficiency
• Minor operating temperature
• Average life extension
• Improved safety
• installation flexibility

OTTAVI srl has taken on the responsibility of finding the line design that would reconcile so definitive and effective the energy aspect with the economic and environmental, demonstrating so that it is economically advantageous to use more efficient equipment constituting terms attractive investment.
The purchase price of a transformer represents only a marginal part of the total cost, while the operating cost (mainly due to the losses, the study design and the quality of construction parts), represents on average 75% - 85%.

Everything has been realized thanks to the study, research and a careful selection of each individual component and material that constitute the machine itself, preferring the maximum quality and compliance with all design criteria and all the regulations currently in force in the sector.

The pole design and research and development to devote to each machine a study of "ad hoc" according to the specific demands of clients. The results are illustrative and sufficient to understand what has reached and exceeded the targets it has set itself:
• Load losses P0 and losses borne by the CCP are lower by 25-35%, even lower classification of RR (reduced losses);
• The yield is between 98.7% and 99.1% MIN MAX;
• Overheating at nominal load are lower than 30% - 50%, it follows a less wear of materials and insulation, extending considerably the life of transformer);
• Greater susceptibility to thermal shock and loading;
• Flexibility and versatility in a variety of installation and atypical sites;
• Increased safety, with classification E2 (resistenzaall'umidità and air pollution), C2 (resistance to climatic variations), F1.

ottavi ecosystem

Low losses
Maximum efficiency
Minor operating temperature
Average life extension
Improved safety
Installation flexibility


ottavi olio

General information
Our oil transformers are manufactured according to CEI 14-4 and IEC EN60076 and can be equipped with accessories on request to better suit the specific needs of Customer. Our standard types of oil transformers are: with the conservative wing with cash, with cash radiators, sealed (no conservative). The transformers can be of the type with two or more windings at full or partial power power, performed with the group standard connection (Dyn 11) or different on request, normal or reduced losses according to the customer's specifications and for frequencies of 50 or 60 Hz.

The core of the transformer is made with magnetic steel grain oriented type low losses, the joints between the column yoke and are interleaved at 45 °. Pressagioghi robust steel section ensure an effective fixing of windings to the core and the locking of the core itself.

The windings of our transformers are built in electrolytic copper insulated with enamel or with pure cellulose paper. Their design provides for the interposition of spacers such as to allow a considerable circulation of insulating oil between the layers. On special request can be executed windings with aluminum conductor.

The cases are manufactured in mild steel plate welded and equipped with suitable reinforcements which sealing against leakage of oil is tested by the method of liquid penetrant. Afterwards the crates are sandblasted and painted inside with special paints oil resistant and externally with paint and cycles approved ENEL. The external finish (paint type and degree RAL) can be varied depending on the specific customer request. Cooling can be performed through the fins forming the walls of the body, or radiators.

The bushings are normally uniform type of porcelain. On special request we can provide the type bushings Elastimold for MT and bushings resin type passabarre for BT.

Normally are installed for the adjustment of the voltage to the MV side switches vacuum-type three, five (optional six or seven) positions or double voltage.

The transformers normally filled with mineral oil dielectric CEI class 1 prior vacuum treatment or on request filled with dielectric oil of the silicone type. All our transformers are subjected to routine tests as required by CEI 14-4 IEC EN 60076. Special supplementary tests can be performed at the request of the customer. On request, we can witness the testing of the machines at the Ns. plant Vs. people.

All our transformers are equipped with amenities such as:
- nameplate;
- thermowell;
- eyebolts;
- castors;
- ground terminal;
- oil drain valve;
- porcelain bushings (MT and BT);
- switch and vacuum ;

can be also equipped with:
- protection box;
- bushings MV Elastimold;
- bushings BT type passabarre;
- sledges support pole;
- Deposit centralization;
- shield between primary and secondary winding;
- Bucholz relay;
- level indicator with or without double electrical contact;
- thermometer double electrical contact;
- air dryer with salts to silica gel;
- overpressure valve;