The transmission system operates at 220kV, 110kV and 66kV, while distribution is mainly at 11kV and 400/230 volts. The supply is 50 hertz alternating current, at 230 volts single-phase or 400 volts three-phase.

Substations

CEM has now in operation nineteen primary substations with a total installed capacity of 720 MVA in 220/110kV, 1,500 MVA in 110/66kV, and 1,752 MVA in 66/11kV, and also operates 1,217 customer substations (11/0.4kV).

Canal dos Patos Substation

Lines and Cables

Power network is made up of underground cables. The main high voltage network operates at 66kV, although some circuits operate at 110kV. For distribution purpose, high voltage is initially converted to MV (11kV), and further reduced to 400/230 volts for customer use.

As of December 2011, CEM’s network comprises 246 km high voltage (110 and 66kV), 597 km 11kV medium voltage and 772 km low voltage cables.

High voltage cable installation

Interconnections with Guangdong Province

The 220kV interconnection with Guangdong Power Grid has been commissioned since June 2008, consisting of 3 circuits connected at a 220/110kV substation “Canal dos Patos,” with importation capacity 1,050 MVA.