Electricity + Control December 2020

TRANSFORMERS, SUBSTATIONS + CABLES

Transformers for Africa’s mega LNG project

David Claassen, Managing Director, Trafo Power Solutions. One of Africa’s most exciting energy projects is procuring dry-type transformers from Johannesburg-based specialistsTrafo Power Solutions. The $23-billion Mozambique liquified natural gas (LNG) project in the far- north Cabo Delgado province represents the largest private, foreign direct investment in Africa to date. It is also one of the largest LNG projects in the world, with the potential to transform the fortunes of its home country and bring economic benefits to the region.

T rafo Power Solutions has already delivered 18 dry- type transformers to site, where they will be employed in the project’s first construction camp which will house about 9 500 contractors. Perhaps the most significant aspect of its contribution, however, is a consignment of 20 highly specialised dry-type transformers for the project’s gas plant, delivering features that only a few players in the global transformer sector could deliver. David Claassen, Managing Director of Trafo Power Solutions highlights some key factors. “Housed in IP56 enclosures, the 20 transformers for the plant – ranging from 400 kVA to 1 600 kVA in capacity – are equipped with very high levels of ingress protection. The enclosures prevent dust particles from entering and provide water protection even from strong water jets.” This specialised solution – achieved in collaboration with Italian technology partner TMC Transformers – is particularly remarkable given the fact that dry-type transformers are cooled by air rather than oil. “The design of these transformers, in terms of elements such as temperature rise, losses and insulation systems, demonstrates the application of world-class technology

and expertise,” says Claassen. “They will be expected to operate reliably in humid and dusty outdoor conditions, providing continuous rated power without the use of any forced cooling.” Each transformer has been individually designed to suit the application and the load it will supply, including different impedances, voltages and K-factors for non-linear loading. They will step down voltages from the medium voltage (MV) network, from 6 600 V to 420 V, and will supply motor control centres which are located in different parts of the plant. Trafo Power Solutions will also be supplying dry-type transformers for a Zone 2 hazardous area of the plant. This means the transformers and their enclosures must be de- signed strictly according to stringent global classifications, and will need to be signed off by an independent profes- sional before being authorised to operate. In the transformer contract for the construction camp, the dry-type transformers from Trafo Power Solutions are included in South African-built modular substations and range in size from 500 kVA to 1250 kVA. “These units have been specially designed for the high ambient temperatures in northern Mozambique,” says Claassen. “While a standard dry-type transformer would typically feature a temperature rise of 100ºC, these will rise to a maximum of only 80ºC when under full load.” Class-H insulation is used on both the medium voltage and low voltage windings, he says. The insulation will withstand a temperature of 180ºC, which is considerably higher than the potential 40ºC ambient temperature in the tropics plus the 80ºC temperature rise of the transformers. In addition, the transformers are designed for levels of humidity up to 95%. He also points out that the modular system in which the transformers are incorporated makes for a simpler and more reliable solution, as all componentry can be assembled and tested under workshop conditions rather than on site. “The 20-foot marine container is then readily transported by road to the port at Durban, and shipped to site for installation and commissioning.”

A modular substation containing a cast resin transformer and associated switchgear.

24 Electricity + Control DECEMBER 2020