Oil power transformers with OLTC up to 145 kV (90 MVA, 138/34.5 kV built)
High-voltage oil power transformers for transmission and distribution substations are made per the catalog up to 50 MVA with insulation class up to 145 kV. A 90 MVA unit at 138/34.5 kV with Dyn11 connection and on-load regulation has also been built.
- Rating
- up to 50 MVA per catalog; 90 MVA built
- Insulation class
- up to 145 kV, BIL 650 kV
- Example
- 90 000 kVA, 138/34.5 kV, Dyn11, OLTC
- Regulation
- OLTC (on-load tap changer)
Price, availability and lead time on request. We help with analogue selection, customs clearance and delivery.
Description
Alongside distribution units, the manufacturer makes high-voltage oil power transformers for transmission and distribution substations. According to the catalog, the range of oil transformers reaches 50 MVA with insulation class up to 145 kV and impulse level BIL 650 kV. The company's products are in operation in more than 90 countries.
In 2026, the manufacturer announced completion of a 90 MVA (90 000 kVA) transformer rated 138/34.5 kV with Dyn11 connection and on-load tap changer (OLTC). The unit is intended for a strategically important substation in Central America. It was assembled in a new production building that expanded the plant's capacity for large projects. Teams took part at every stage, from design to manufacture and final assembly.
Transformers of this class are designed to the requirements of a specific project. The voltage ratio, connection and vector group, OLTC type and range, cooling system, and noise and loss requirements are agreed. As in the distribution line, anti-corrosion coatings for severe climates, reinforced designs for seismic regions and eco-friendly insulating fluids are used. The design is with a conservator.
Tests are carried out under IEC standards. Routine tests cover winding resistance, transformation ratio, vector group, dielectric tests, and no-load and short-circuit losses. Type tests are carried out for lightning impulse, temperature rise and noise level, and special tests for short-circuit withstand by agreement. Applications cover 66–138 kV substations of grid companies, power evacuation nodes of hydro, PV and wind plants, and large industrial consumers. The exact parameters of each unit are defined for the project.
The main components of such a transformer are the active part with core and windings, the tank, HV and MV bushings, the OLTC and the cooling system. The OLTC makes it possible to maintain network voltage without disconnecting the load. The conservator takes up the change in oil volume during heating and cooling. The customer's requirements for noise, losses and dimensions are fixed in the technical specification before design begins. Installation and maintenance of such units are carried out on site according to the instructions, and control measurements are made before commissioning.
Technical specifications
| Rating | up to 50 MVA per catalog; 90 MVA built |
|---|---|
| Insulation class | up to 145 kV, BIL 650 kV |
| Example | 90 000 kVA, 138/34.5 kV, Dyn11, OLTC |
| Regulation | OLTC (on-load tap changer) |
| Design | with conservator |
| Standards | IEC 60076 |
Replacement for
ТМН-6300/35, ТД-10000/35, ТДН-16000/110, ТРДН-40000/110, ТРДЦН-63000/110, ТРДЦН-80000/110
selected by purpose and main parameters, please confirm with our manager
Request a price and lead time
Oil power transformers with OLTC up to 145 kV (90 MVA, 138/34.5 kV built). We reply within one business day.
Or email sales@usk.ua or call 044 339-50-20.
Questions and answers
What rating and voltage class do the oil power transformers of this line have?
Per the catalog the range reaches 50 MVA with insulation class up to 145 kV and BIL 650 kV. A 90 MVA unit has also been built.
What are the parameters of the 90 MVA transformer that was built?
Rating 90 000 kVA, voltage 138/34.5 kV, Dyn11 connection, on-load regulation OLTC. The unit is intended for a substation in Central America.
What facilities use such transformers?
66–138 kV substations of grid companies, power evacuation nodes of hydro, PV and wind plants, and large industrial consumers. Tests are carried out under IEC 60076 standards.
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