Tag Archives: David Claassen

Trafo Power Solutions helps sustain iron ore exports at Saldanha Bay

Trafo Power Solutions recently supplied specialised transformers for the Tippler 3 project at the iron ore load-out station at the port of Saldanha Bay, in South Africa, as part of an upgrade Transnet is currently conducting at the facility.

The construction of a third tippler at the Saldanha Bay port is to sustain iron ore export volumes of 60 Mt/y when the existing tipplers are refurbished in the future. It will integrate with the rail system bringing ore via the 860 km line from mines in the Northern Cape of the country.

Key aspects of the new infrastructure comprise the 285 t tippler itself, a loading vault below ground and a conveyor tunnel. New buildings, service roads, bridges, railway lines, conveyors, lighting and bulk electrical supply infrastructure are also part of Transnet’s upgrade project, according to Trafo.

Factory-acceptance testing of the dry-type transformers were completed in December 2019, according to Trafo Power Solutions Managing Director, David Claassen, with delivery to site taking place in February.

Trafo Power Solutions’ contract was for the design, supply and commissioning of five dry-type transformers. There are two 1,000 kVA units and a 3,150 kVA unit, both stepping down from 11 kV to 400 V, the company said. The other two units are 3,500 kVA and 4,500 kVA capacity, respectively, taking 11 kV to 3.3 kV.

To resist the corrosive sea air, all the transformer enclosures were manufactured from the 3CR12 grade of stainless steel, according to Trafo. The enclosures are also IP33-rated to ensure a high level of ingress protection against moisture and dust.

“The enclosure design also incorporates cable boxes and Type C totally enclosed plug-in bushings for the terminations,” Claassen says. “This provides a boot covering, which is touch-potential safe, and also provides for efficient plug-and-play installation.”

This is a significant improvement on the regular lug and bolt copper connection, which would just be shrouded by a heat-shrunk material, according to the company. The special terminations also facilitate easier maintenance or removal.

“The units will provide the medium-voltage supply for the Tippler 3 project and its associated infrastructure, including equipment like conveyors,” he says. “All the transformers will be supplying non-linear load to a certain extent, so they have been designed with a K-factor of four.”

The K-factor is a measure of a transformer’s ability to withstand the heating effects of non-sinusoidal harmonic currents created by electronic equipment, Trafo explained. “The higher the K-factor, the greater the harmonic heating effects,” the company said.

As dry-type transformers are cooled without the use of oil, these units will receive forced ventilation when a pre-set temperature is reached. This ventilation is provided from a row of fans which Trafo designed to be bolted below the location of the transformers.

Designed locally in South Africa by Trafo Power Solutions, these dry-type transformers are manufactured in Italy by strategic partners TMC Transformers, which focus on cast resin transformer technology. All products are routinely factory-tested according to IEC standards, but type-testing and special testing can also be conducted, according to the company.

“The standard applicable to dry-type power transformers is IEC 60076-11,” Claassen says. “TMC’s advanced laboratory facilities allow us to conduct the full range of tests in-house, in accordance with what these standards and whatever other requirements are designated by the customer.”

At Saldanha, Trafo is also responsible for building auxiliary protection and control panels, which it locates remotely from the transformers. These include temperature control sensors that communicate with the port’s broader control and monitoring network.

Trafo devises mobile dry-type power solution for coal mine

In a specialised application on a coal mine, Trafo Power Solutions has supplied a dry-type transformer mounted on a mobile skid.

David Claassen, Managing Director at Trafo Power Solutions, said: “The harsh environment of a coal mine required us to specially design a fit-for-purpose solution.

“The cast-resin dry-type transformer is ideal for the mobile arrangement as it is cooled without oil,” he explained. The absence of oil makes it a safer option in terms of fire hazards, especially on a coal mine.

It is also more environmentally-friendly, as there is no chance of an oil spill, according to the company. The 1,250 kVA dual-MV configuration supplied to this mine allows the unit to be linked up to either 11 kV or 6.6 kV supply.

“The unit was designed for a compact enclosure, while still allowing for sufficient air movement for cooling,” Claassen said. “We provided a unique solution of a cast-resin transformer with Class H insulation rating for both the medium voltage and the low voltage windings.”

This insulation standard ensures the transformer can withstand temperatures of up to 180°C, according to Trafo, with Claassen noting that the enclosure design had to accommodate these heat factors while also preventing the ingress of dust or water.

Special engineering was also applied to building a high level of mechanical rigidity into the transformer itself, as demanded by the regular relocation of the mobile skid. This movement means vibration and other forces must be borne by the equipment without affecting its performance.

Claassen emphasises that Trafo Power Solutions is experienced in providing dry-type transformers in a range of enclosed formats to suit customers’ needs. The inherent safety of these transformers also allows them to be installed in underground mining locations.

“We can provide various dry-type transformer enclosed solutions with a mobile skid, which is a versatile format for a range of mining applications,” he says.

Trafo Power Solution’s track record in cast-resin transformers is based on its local expertise and design capacity, combined with the high quality manufacture of the units by Italy-based TMC Transformers.

Trafo powers through at Mpumalanga coal mine

Trafo Power Solutions says it has recently completed a dry-type transformer contract as part of a significant upgrade at a coal mine, in Mpumalanga, South Africa.

This involved the design, supply and installation of two 200 kVA – 22 kV-400 V – dry-type transformers, according to Trafo Power Solutions Managing Director, David Claassen. Housed in specialised IP42-rated ingress protected enclosures, the units were specified by a design house on behalf of the end-customer, the dry-type transformer leader said.

“The contract demonstrated our application engineering capability and our experience in co-ordinating our solution within a larger project,” Claassen said. “This included meeting detailed specifications, and ensuring that our design for the transformers and their enclosures matched the requirements and constraints of the site.”

Trafo Power Solutions also equipped the units with the necessary earth fault protection and surge protection, as well as vibration pads, it said.

“Dry-type transformers are well suited for the coal mining environment, with its hazardous areas and its regulations to mitigate fire risk,” Claassen says. “The dry-type technology uses air to cool the transformers, doing away with the need to use oil as a coolant.”

Claassen emphasised that the absence of oil has advantages for safety, as the oil ignition potential is removed. The units can also be protected against fine airborne coal dust. An added environmental advantage is the lack of oil leaks contaminating the ground or water, too.

Trafo transforms fortunes at KwaZulu-Natal mining operation

Trafo Power Solutions recently came to the aid of a mining company in KwaZulu-Natal, South, Africa, suffering from a transformer failure.

Following the incident, dry-type transformer specialist, Trafo, designed, built and delivered a non-standard cast-resin replacement for the company – in just five weeks.

David Claassen, Managing Director of Trafo Power Solutions, said: “Once the situation with the old transformer was assessed, it was decided it would be more economical to replace the unit than to embark on major repairs.

“We were able to accommodate the customer’s specifications in our replacement design, and have the unit manufactured by our European partners (the TMC transformers facility, in Italy, pictured) in just four weeks. After that, it took just a week to fly in the transformer and deliver it to the customer.”

Claassen said it is not uncommon for transformer replacements of this scale to take anything from 12 to 14 weeks, with Trafo’s rapid turnaround time highly valued by the customer.

The mine required a 1,600 kVA dry-type DYN11 transformer that stepped 33 kV down to 550 V, with a non-standard tap setting arrangement of seven tap settings instead of the normal five.

Dry-type transformers – also called cast-resin transformers – are growing in popularity as users recognise their safety benefits, as well as their economy and flexibility of placement, according to Trafo. To meet this demand, Trafo works in close collaboration with established and well-resourced manufacturing partners in Europe to source tailored designs that meet customers’ exacting specifications, it said. This comes on top of ongoing after-sales service.

Trafo transforming mobile process plant operations at Sierra Leone mine

Trafo Power Solutions says four of its dry-type transformers have been proving their worth on a mobile process plant at a Sierra Leone mine since last year.

The dry-type transformers have been so successful in powering the process plant that the customer has ordered six more for its recent phase two upgrade.

Trafo Power Solutions Managing Director, David Claassen, said: “The mine required a solution that would withstand the demanding conditions of a mobile process plant needing to be moved frequently over rugged mining terrain – as often as once a month. They could not risk using a conventional oil-cooled transformer as they needed to avoid any risk of fire or oil leaks. They also needed a product that would require little to no maintenance.”

The second contract was a repeat of the initial order and comprises two 800 kVA units, one 1,600 kVA unit and one 2,000 kVA unit as well as a further two transformers – 1,600 kVA and 800 kVA – which will replace two existing oil filled transformers.

The company said: “Demonstrating its flexibility in meeting specific customer requirements, Trafo Power Solutions designed the solution to cater for the mine’s unusual voltage levels of 13.2 kV/480 V at 60 Hz.”

The transformers are installed in a 6-m-long E-house on the mobile process plant, which is moved around the site on skids as required by the mining plan.

“We were able to customise the design of the transformers for the customer’s specific application,” Claassen said.

“This required a special reinforced frame to accommodate the constant vibration of the working plant, as well as the bumping motion when the skid-mounted plant is dragged to a new location. The design also included anti-vibration damping on the transformer feet, to further mitigate the impact of the vibration.”

The entry of Trafo Power Solutions dry-type transformers to the African market coincides with a growth in the use of modularised sub-stations, according to the company. “Due to the absence of oil as a coolant in dry-type transformers, they are suitable to be used in confined spaces without any of the conventional infrastructure usually necessary to protect the environment from possible oil spillage,” Trafo said.

Claassen said: “Modular and mobile sub-stations are growing in popularity for applications all around Africa, as they can be fully prepared under workshop conditions, reducing the work required on site.

“In terms of the installation of the transformer, for instance, we ensure that the temperature control relays are fully programmed and tested in South Africa, along with the fan system – making it ready for action on site.”

In the unlikely event of any further attention being necessary, Trafo Power Solutions can mobilise service support to any of the sites it supplies, it said.

Trafo bringing low loss cast resin transformers to Africa market

Trafo Power Solutions, which provides transformer technology to remote mine sites across Africa, is recommending companies make the most of recent improvements in the design of these transformers in order to boost safety and energy efficiency.

According to Trafo Power Solutions Managing Director, David Claassen, there have been considerable strides in technology, surpassing both the efficiency and the reliability of the traditional oil-filled transformers predominantly used in power grid systems.

These high efficiency solutions include open-wound transformers (OWTs), vacuum-pressured impregnated transformers (VPIs) and cast resin transformers (CRTs). Traditional oil-filled transformers use paper saturated in oil wrapped around the winding material as an insulation medium. If not maintained correctly, insulation degradation will occur, with the oil posing both a safety and environmental risk, according to Trafo.

“OWTs are constructed by dipping preheated windings into a high temperature varnish bath and then baking the high temperature varnish,” said Claassen. “This replaces the need for oil and paper, so only a small amount of material is flammable.”

In VPI construction, layers of polyester resin are applied to the windings, which are subjected to interchanging cycles of pressure and vacuum that ensures deeper penetration. This reduces the chances of air voids, the company said.

“With CRTs, windings are placed in a mould which is filled under vacuum with resin epoxy,” he said. “Fibreglass reinforcing mesh is used to further strengthen the windings, which are cured in a heat-controlled oven. This process also prevents air voids, and the resin in CRTs is non-flammable.”

These designs have also made advances in reducing losses, and thereby improving efficiencies, Trafo said. Some 84% of a transformer’s losses at full load are copper losses – also known as load losses – and are due to current flowing through the winding conductor itself. The remainder are core losses, or ‘no load’ losses, pertaining to the core steel losses, according to Trafo.

“The use of OWTs, VPIs and CRTs offer considerable savings in energy costs of their life-spans – which for CRTs, for instance, averages about 20 years,” Claassen said. “Despite the slightly higher capital cost of around 20%, these technologies can repay the price differential in just four years.”

Claassen said low loss cast resin transformers are being used exclusively in many parts of the world, including Europe and North America. Although there is a 12 to 15% premium on these, the payback period is between two to four years, he said. These are now available for the African market from Trafo Power Solutions.

One of Trafo Power Solutions recent mine site installations was at Alphamin Resources’ remote Bisie operation in North Kivu province, DRC.