Electricity + Control April 2019

TRANSFORMERS + SUBSTATIONS

Quality testing The in-house test lab handles all required routine testing for SANS 780:2009 and IEC standards for transformers such as lightning impulse and noise level testing. Specifically, internal arc testing which is required for the especially high standards for safety in electrical reticulation, is carried out on a complete mini-substation, in accordance with IEC specification, using different ring main units ac- cording to customers’ preferences. Type tests, to test equipment for endurance in specific harsh environmental conditions, for ex- ample, are carried out on different sizes of units, by independent standards organisations in South Africa and internationally. All test results are also referred to the group’s headquarters in Brazil for ratification and to provide international clearance on equipment produced in South Africa. It is worth noting that WTA has participated, by invitation and over many years, in the SABS spec- ifications review working group on transformers and miniature substations. The company therefore contributes from its own knowledge and experi- ence to maintaining and building quality standards in the sector and is always up to date with the lat- est standards specifications. Global connections Alongside its own in-house research and tech- nology innovations, WTA has the backing and support of WEG Transmission and Distribution Brazil, which has a research and development department dedicated to advancing design and materials and manufacturing efficiencies. It also has access to the centralised engineering design database held at the WEG Group’s headquarters. This is a global resource that holds the whole his- tory of design development through the group’s experience across different projects. It supports design optimisation and material efficiencies for

each new project, building on lessons learnt and adjustments or refinements applied through past projects. The WEG Group also encourages skills devel- opment and skills exchange. WTA has already ben- efitted from WEG Transmission and Distribution engineers being seconded to its facilities. On par- ticular projects where Brazilian operations have ex- isting experience, in engineering, project planning and management, manufacturing specifications and/or on-site installation and commissioning, WEG Transmission and Distribution will second skills toWTA to work with the local team. This pro- vides for skills sharing, supports local training and builds local learning and experience. Current markets It is interesting to note that in the current market, about 60% of all production orders placed with WTA Wadeville are going to sub-Saharan Africa projects and 40% to South African projects. On av- erage, the bulk of production capacity is commit- ted to manufacturing transformers with miniature substations making up the balance. Demand for transformers across the continent – Botswana, Mozambique, Zambia, Ghana – is coming mainly from the mining sector. At home, WTA continues to supply transformers and min- iature substations to Eskom as well as municipal electrical utilities and other customers. Brown notes that the company is now seeing new demand growing in the renewables energy sec- tor, where different technologies and controls apply. “Here, we’re dealing with inverters, factors like har- monic distortion and intermittences in supply, as well as the need for storage capacity. The WEG Group’s Brazil headquarters has engineering, product and project references from its experience in this sector. That gives us atWTA a head start in designing equip- ment for transmission and distribution in the renew- ables energy market opening up in South Africa.”

Left: A WTA 500 kVA, 11 000/420 V miniature substation fully tested to SANS 1029 specification and successfully released by the BIVAC inspector for export. Centre: A typical vandal- proof 500 kVA miniature substation for Eskom, with 6 mm mild steel cubicles, additional bracing and a 4-point locking system on the doors, welded covers and heavy-duty door lock covers. Right: The oil filling process under way on a typical distribution transformer in the tanking department.

30 Electricity + Control

APRIL 2019