Thermal behavior of a GIS three-phase transformer

27 February 2024
Transformador trifásico

“Our electrical laboratories are accredited by @ILAC according to the ISO/IEC 17025 standard for carrying out electrical tests on conventional instrument transformers and sensors”

Evaluation of the thermal behavior of a SF6 free GIS type three-phase power-voltage transformer

TECNALIA performs in its High Voltage Laboratory an evaluation of the thermal behavior of a three-phase power-voltage transformer with up to 45.000 VA of power to be installed in GIS type substations, manufactured by ARTECHE and insulated by GE Vernova’s g³ gas.

The SF6 gas insulated switchgear is the solution with which the GIS type substations have been designed in the last years for the electric systems with highest voltages due to this gas’ great capability to provide dielectric insulation. But SF6 also has its downsides, like its great global warming potential (GWP), and the energy transition requires a more intelligent but also environmentally friendly power grid. Is there any viable alternative?

European institutions seek the complete removal of SF6 from the power grids in their borders, the first prohibitions for new installed equipment insulated with this gas coming into effect in 2026. For this reason, the electrical equipment manufacturers are looking for technical solutions in this field, counting with TECNALIA to position themselves in the direction of decarbonization.

In this context, TECNALIA’s High Voltage Laboratory has successfully completed thermal behavior evaluation tests on a 72,5 kV SF6 free GIS type three-phase power-voltage transformer manufactured by ARTECHE. This transformer is not only special because of its high power, 45.000 VA, but also due to its three-phase encapsulated configuration insulated with an alternative gas.

The tested transformer is insulated with g³ gas by GE VERNOVA. This alternative insulating gas has a global warming potential (GWP) 99% lower than that of SF6 and therefore represents a milestone in the power grids’ decarbonization.

The thermal evaluation tests have consisted of high voltage application to the three-phases, loading the transformer’s six secondary windings together -two secondaries per phase: one for accuracy and another one for power supply- and monitoring the temperature-rise of the different components of the equipment. The performed heating cycles have included diverse sequences in normal service conditions, with primary voltage applied up to 190% of its rated value, and with repeated overloads.

With the performed test, TECNALIA’s Electrical Equipment Laboratory has been able to define the thermal behavior of the transformer, thus allowing to broaden the knowledge of the equipment that will be part of the power grids of the future.

Our electrical laboratories are accredited by @ILAC according to standard ISO/IEC 17025 for the performance of electrical tests in conventional instrument transformers and sensors.