December 13, 2017

Dry-type transformers ideal for modular substations

The Trafo dry-type transformer is ideally suited to this application as it can be mounted inside the modular structure

The introduction of Trafo dry-type transformers to the African market comes just at the right time for the end-user, as a number of industry sectors embrace the growing trend towards modularised substations.

“Due to the various benefits and the cost effectiveness of modular substations – which are fitted into either a marine container or a specially fabricated E-house – dry-type transformers are becoming more popular,” says David Claassen, managing director of Trafo Power Solutions. “The Trafo dry-type transformer is ideally suited to this application as it can be mounted inside the modular structure; this cannot be done with the traditional oil-filled transformer.”

Claassen highlights that safety is the prime concern in the design and construction of substations. Due to its design and the absence of oil as a coolant, the dry-type transformer is simple and safe, allowing extensive test work to be conducted with the modular unit prior to the full solution being sent to site. This in turn reduces the costs associated with site installation, assembly work and commissioning.

“There is an historical misconception that dry-type transformers are too large to be housed within a container, but this is not so,” he says.

Including the dry-type transformer inside of the modularised substation has the cost saving benefit of eliminating the need for civils infrastructure that is needed for oil-filled transformers have to be located outside of the substation for safety reasons. This type of civils work includes foundations and a plinth on which the unit can stand as well as special purpose bunding walls to contain oil leaks This not only increases the cost of the installation, but lengthens the time frame in which the substation can become operational, and the cost of this additional civils infrastructure in the more remote areas of Africa is also particularly high.

Sourcing dry-type transformers from industry pioneer and leader Hammond Power Solutions (HPS) gives Trafo Power Solutions the flexibility to meet specific and unusual requirements from customers.

Drawing on the depth of technical expertise within HPS and its manufacturing facilities in Italy, an appropriate solution can always be found without compromising the quality of the product.

“In a recent E-house application that Trafo Power Solutions provided for a mining project in Sierra Leone, a 2,000 kVA dry-type transformer was specified as part of the mobile mining unit,” says Claassen.

“We supplied four dry-type transformers in total: two 800 KVA units, one 1,600 KVA unit and one 2,000 KVA unit. The unusual voltage levels that were required – 13,2 KV/480 V at 60 Hz – demonstrated our flexibility in meeting specific customer requirements.”

The focus at Trafo Power Solutions is all about finding a solution for the customer, he says, outlining other elements that made this project a success. The scope of supply included temperature control units along with cooling fans. These will be automatically switched on in the event of a failure of the master cooling system and will ensure minimum downtime while the system is repaired.

Another useful function of the cooling fans is to allow the transformer to increase its power output in the event of an overload situation. Surge arrestors for each transformer were supplied as an added protection against the risk of an unstable voltage supply.

Parts of the substation such as potential transformers (PTs) are specifically designed and manufactured for outdoor use with a rating 13,2 KV/110 V AC, 500 VA for protection purposes mounted near the auto reclosers.

Claassen says that because these mobile mining units are transported to site and in some instances moved from area to area within a mine, it is critical that the structural integrity meets this type of arduous application. “Trafo transformers are engineered to withstand harsh vibration and are robust in construction, however where required it is possible to reinforce the rigidity further.”

“We find solutions and offer flexibility through understanding the customer’s specific needs and applying an agile approach,” he says. “Traditionally, this type of equipment would be on the critical path for a project, but we managed to have them manufactured within a five-week window, which allowed for a rapid delivery to the customer.”

Claassen emphasises the high energy efficiency of these transformers, leading not only to lower energy consumption but also to less energy loss through heat; this means less is demanded from the ventilation and cooling systems on these units.

An extra benefit – especially for remote sites such as mines in rural areas of Africa – is that a dry-type transformer is virtually maintenance free, significantly lowering its operating cost.

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