WEG Transformers: Power, Distribution and Dry-Type

Short answer

WEG, a Brazilian manufacturer of motors and electrical equipment, makes power transformers, autotransformers, distribution, pad-mounted and dry-type transformers. In Colombia it has a transformer plant in Sabaneta, Antioquia, where it has built 145 kV class power units, and it supplies larger units from its plants in Brazil.

What it is and where it is used

WEG is a Brazilian manufacturer best known for its electric motors, which also makes power transformers, autotransformers, distribution, pad-mounted and dry-type transformers. In Colombia it has a transformer plant in Sabaneta, Antioquia, and it supplies larger projects from its plants in Brazil.

Its transformers are in utility substations, solar farms, industry and buildings. As public examples, WEG announced for a Colombian utility three-phase transformers of 60 and 40 MVA of the 145 kV class and units of 4 to 20 MVA manufactured in Sabaneta. It also announced single-phase 50 MVA autotransformers of the 245 kV class manufactured in Brazil. For a solar farm in Colombia it announced two 190 MVA, 230/34.5 kV transformers. For the technical context, see power transformer.

Variants: power, autotransformer, distribution, pad-mounted and dry-type

Line	Application	Main difference
Power transformer	Substations and power plants	Oil-immersed, with a tap changer depending on the application
Autotransformer	Interconnection of high-voltage networks	Common winding between two voltages (guide)
Step-up for renewables	Solar and wind farms	Raises the farm’s medium voltage to the grid voltage
Oil-filled distribution	Networks and commercial	Pole-mounted or substation
Pad-mounted	Underground distribution	Dead-front enclosure
Dry-type	Indoor, buildings, industry	No oil (guide)

The power, voltages, vector group and cooling are read from the nameplate. The maximum ratings of each plant are defined by WEG for each project.

Main features

Local and regional manufacturing: a plant in Colombia for medium ratings and plants in Brazil for larger and higher-voltage units.
Power transformers with an on-load tap changer, cooling and their own protections.
Integration with the rest of the WEG portfolio (motors, drives, switchgear) in industrial projects.
Distribution and dry-type for networks, buildings and industry.

Communications and integration

The transformer does not communicate by itself. Temperatures, oil level, the Buchholz relay, the pressure relief device and the tap changer position reach the protection and SCADA through contacts and transducers, or through an online monitoring system. On a solar farm, these signals are integrated into the plant SCADA together with the protection of the step-up substation.

Frequent technical questions

Large WEG transformers: this refers to the high-rating units that WEG publishes in its news; for a specific project, the capacity is confirmed by the manufacturer.
Receiving on site: acceptance tests are compared with the factory protocol; see transformer factory tests.
Trip on energization: the inrush current can make the differential or the overcurrent protection operate; see transformer trip on energization.
Oil and dissolved gases: periodic analysis warns before a failure; see dielectric oil analysis.
WEG transformer made in Brazil or in Colombia: the nameplate shows the plant of origin; the documentation and the test protocol are delivered by WEG with each unit, regardless of where it was made.
Step-up transformer of a solar farm: besides the transformer tests, the substation protection and the signals required by the utility are verified.
Tap changer that does not respond: check the motor drive, the limit switches and the automatic voltage control.

Brazilian standards that accompany a WEG transformer

A WEG transformer made in Brazil may come with documentation that cites ABNT standards, in addition to IEC. The ones met most often are:

ABNT NBR 5356. Power transformer series, equivalent in structure to IEC 60076. Part 1 covers general matters, part 3 the insulation levels, dielectric tests and air clearances, and part 9 the receiving, storage, installation and maintenance of liquid-immersed transformers. That last part works as a checklist even when the contractual standard is IEC.
ABNT NBR 5440. Requirements for transformers for overhead distribution networks.
Vegetable liquids. NBR 15422 is the standard for vegetable insulating oil for electrical equipment, NBR 16518 gives the guidelines for monitoring and maintaining that oil and NBR 16431 covers material compatibility with it. For natural ester, IEEE C57.147-2018 is a guide to acceptance and maintenance of the fluid, aimed at manufacturers and operators.

The most common Portuguese terms in a protocol are perdas em vazio (no-load losses), perdas em carga (load losses), impedância (impedance), elevação de temperatura (temperature rise), ensaios de rotina (routine tests) and ensaios de tipo (type tests).

Two public projects that show where the line is heading

Vegetable oil at the Itaipu plant. According to the sector press (Cenário Energia, 17 February 2025), WEG developed and supplied equipment for the expansion of Sector 1 of the Margem Direita substation, on the Paraguayan side of Itaipu. The equipment is a 66/23 kV, 10 MVA power transformer insulated with vegetable oil and a 23/13.8 kV, 5 MVA dry-type transformer. It also includes 75 kVA, 23,000/220 V pad-mounted station service transformers in vegetable oil, and a 72.5 kV three-pole disconnector. Delivery was completed in the second half of 2024. The article highlights that vegetable oil is biodegradable, of renewable origin and has a higher flash point, and that a technical study by Itaipu concluded that its performance and efficiency are equivalent to those of conventional equipment. The article does not specify the plant species or the standard.

Hybrid paper and uprating at Antonina (Paraná). In an R&D project by ANEEL and COPEL with WEG, UFSM and VEGOOR, a 1969 transformer of 13.8/230 kV and 70 MVA at the Governador Parigot de Souza plant was raised to 73.6 MVA. Hybrid paper (the article cites Nomex 910) was used instead of Kraft paper in the high-voltage windings, the mineral oil was replaced with a vegetable insulating liquid and a fiber-optic temperature measurement system with 16 sensors was installed. The article reports that the goal is to extend service life, but it gives no number of years or temperature values.

What changes in testing with natural ester

Oil analysis of a transformer with vegetable liquid uses different limits from mineral oil, because the liquid has a different viscosity, a different flash point and a different moisture behavior. The dissolved gas and moisture criteria are requested from the fluid manufacturer and checked against the IEEE C57.147 guide; see dielectric oil analysis. With hybrid paper, the interpretation of moisture and solid insulation aging also changes. In both cases, the electrical tests (ratio, winding resistance, power factor, frequency response) are done the same way, but the reference value must be the one in the protocol of that unit.

Points to watch at receiving

Verify the plant of origin on the nameplate (Sabaneta or Brazil) and that the protocol corresponds to that serial number.
Confirm the insulating fluid on the nameplate before topping up or filling levels: fluids are not mixed without the manufacturer’s approval.
If the unit comes from Brazil, review the transport documentation (impact recorders, inert gas pressure) and the packing list for each dismounted accessory.
On a solar farm step-up transformer, confirm with the utility the tests and signals it requires; see transformer factory tests.

How we help

At Tiza Group we do not sell transformers. We test and commission WEG transformers and those of any brand: ratio, winding resistance, insulation, power factor, frequency response, tap changer and its own protections, plus the protection scheme. This fieldwork is done in Colombia, or elsewhere on request. See power transformer testing within testing and commissioning. If the transformer is part of a solar plant, we also do the commissioning of solar plants. Write to us through the contact page.

References

IEC 60076-1, power transformers: general.
IEEE C57.12.00, general requirements for liquid-immersed distribution, power and regulating transformers.
WEG, corporate news «WEG transformers strengthen energy infrastructure in Colombia» and «WEG supplies transformers for solar project in Colombia».

Frequently asked questions

Does WEG manufacture transformers in Colombia?

Yes. WEG reports that it has a transformer plant in Sabaneta, Antioquia. In a contract with a Colombian utility it announced 60 and 40 MVA transformers of the 145 kV class and units of 4 to 20 MVA manufactured there, and 245 kV autotransformers manufactured at its plants in Brazil.

Where can I find the manual for a WEG transformer?

The installation, operation and maintenance manual and the factory test protocol come with each unit; WEG also publishes general documentation in its download center. Request them with the serial number from the nameplate.

What tests are performed on a new WEG transformer?

Those of any transformer of its type: ratio, winding resistance, insulation, power factor, oil analysis and, on power units, frequency response, tap changer and its own protections. The results are compared with the factory protocol.