Installation of the 1st 525 kV Insulated Cable in Brazil

In recent years, alternative solutions based on insulated power cables have been progressively applied at voltage levels up to 230 kV and, in specific cases, 345 kV. This technology provides increased flexibility for compact layouts and constrained sites.

The conventional solution remains economically attractive due to lower implementation costs, supplier availability, and standardized maintenance practices. However, insulated cable systems offer advantages in terms of operational safety, reliability, and mitigation of risks associated with environmental interferences and insulation failures. Under specific site constraints, these alternatives may also present competitive overall costs. This paper presents the studies and solutions adopted for the installation of a second autotransformer bank rated 3 × 500 MVA, 525/440 kV. The project applies the conventional solution in the 440 kV yard and an XLPE insulated cable solution in the 525 kV yard, including the integration of an existing backup unit commissioned in 2004. It represents the first application of an insulated cable system at the 525 kV level in Brazil.