At the end of 2013, the RNT (National Transmission Grid) consisted of 8 733 km in lines and 67 transformer substations and 13 step down, switching and transition substations.

  2013-12-31 2012-12-31 VARIATION
Length of lines in service (km)  8.733  8.534  199
400 kV  2.430  2.333  101
220 kV  3.565  3.521  44
150kV  2.734  2.680  54
Transformation power in service (MVA)  34.984  33.915  1.069
Autotransformation  13.410  13.410  0
400/220 kV  6.750  6.300  450
400/150 kV  5.540  5.990  -450
220/150 kV  970  970  0
150/130 kV  150  150  0
Transformation  21.574  20.505  1.069
400/60 kV  3.910  3.230  680
220/60 kV  11.512  11.443  69
150/60 kV  5.692  5.692  0
150/130 kV  140  140  0
220/30 kV  320  0  320

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The RNT provides power flow from production plants to the transformer substations where it is fed to the National Distribution Grid at 60 kV.

The RNT also connects to the European Transmission Grid through 9 interconnection points with the Spanish Transmission Grid as well as delivering VHV directly to numerous consumers.

The National Dispatch Centre in Sacavém (Loures) coordinates general operations and ensures
balance in the National Electricity System. The Network Operations Centre in Vermoim (Maia) is responsible for the Monitoring and Remote Operation of all National Transmission Grid equipment.

The Corporate Telecommunications Network uses this infrastructure extensively (fibre optic and hertzian beams) to provide data transmission services, control commands to network elements and the communications facilities required for operating the RNT.

The interconnection with the Spanish Transmission Network is provided by one 130 kV line
between Minho and Galicia, three 220 kV lines at Douro International and by five 400 kV lines, two between Minho and Galicia, one at Douro International, one at Tejo International and one between the Alentejo and Estremadura. The national stretch of a new 400 kV interconnection is now concluded between the Algarve and Andalusia.