A new load dispatching centre for the capital is also to be constructed complete with control centre, a Siemens statement said.
The German company will also train technical personnel locally and ensure that the power supply is maintained while the network conversion project is implemented.
"With the modernized and expanded network and with sophisticated control centre technology, we will not only be able to offer our commercial and industrial consumers greater reliability and higher quality of the power supply, but better service as well," CEB General Manager D R Pullaperuma was quoted as saying in the statement.
Colombo's power supply system is being modernized and expanded in order to meet the increasingly high standards required for the city's power supply, it said.
This will ensure that the over 600,000 people living in the port city, which covers an area of more than 37 square kilometres on the west coast, will have a reliable supply of energy in the future too.
As part of this network expansion project, Siemens will deliver 390 air-insulated medium-voltage switchgear panels, 40 compact stations, 30 ring main units, 72 low voltage distribution panels and medium- and low-voltage cables.
In addition, Siemens will modify 175 distribution substations in the urban network.