Tag Archives: transformers

Trafo Power Solutions bolsters dry-type transformer contingent at Alphamin’s Bisie mine

Five years since Trafo Power Solutions supplied Alphamin’s Bisie tin mine in the Democratic Republic of Congo with two dry-type transformers, the mining company has now ordered another three of these modular substations equipped with dry-type transformers to keep up with the mine’s expansion.

“This latest order is testament to the operational performance of our dry-type transformers at Bisie mine over the past five years,” David Claassen, Managing Director of Trafo Power Solutions, said. “There were numerous challenges that our design had to accommodate, not least of which is a very arduous section of road in the journey to the mine.”

The mine’s location in the Walikale Territory of DRC is remote, being about 180 km northwest of Goma. Like the initial order, the three 3,000 kVA, 400 V/11 kV substations will be supplied in standard 6 m containers to facilitate transportation. However, specialised steel bracing is required – to withstand the challenging road conditions, especially over the last part the journey.

“These conditions make the road almost impassable by any vehicle other than a six-wheeled Unimog,” Claassen says. “There is intense vibration and tilting of the cargo on these trailers, so our design and bracing is done with this in mind.”

He notes that the mine had considerable foresight in specifying the first dry-type transformers, especially given the relative novelty of this option at the time. At that stage, it tended to be standard practice to use oil-filled transformers for this type of application. Apart from the logistics, the substation solution also had to withstand the equatorial climate and frequent lightning strikes.

“The region where the mine is located is ranked in the top five most vulnerable to lightning strikes, so there is a high risk of damage to equipment related to electrical surge,” Claassen says. “We therefore designed robust surge protection solutions on both the medium voltage and low voltage sides of the substations, and for the transformers.”

Given the warm climate, Trafo Power Solutions designed a fully redundant N+2 cooling system for the transformers; this means that each transformer is cooled by two fans, with another two fans on standby. Among the advantages of dry-type transformers in this climate is that the MV winding is completely cast in resin, so is highly resistant to humidity.

E and I Zambia helps power up process plant for copper miner

Electrical control and instrumentation specialist, E and I Zambia, says it has successfully completed a large project on a new process plant for one of Zambia’s leading copper miners.

The contract included the installation of six electrical substations, 20 transformers, five 1,250 kVA diesel generators for back-up power and a 950 m overland conveyor. Almost 250 km of cable was pulled and nearly 15 km of cable racking was constructed, according to the company.

Also completed were six earth mat rings, 12 mast lights and a range of general plant earthing and lighting installations around the plant, as well as the fitting and termination of instruments. E and I Zambia conducted the work between January 2019 and April 2020, in close collaboration with both a leading design house and the end-client, the company said.

According to Projects Manager, Dave Opperman, the company has a sound track record in the country, having been active on the copperbelt and beyond since 2002.

“The experience of our team on site, the quality of our artisans and the training of workers ensured that the quality of this job was world class,” Opperman says. “While prioritising safety and quality, we were still able to adapt to the inevitable fine-tuning of project parameters and schedules, and to deliver on the client’s timelines.”

The safety standards were reflected in the achievement of 395 Lost-Time Injury Free days. This was achieved despite a busy site – peak manpower grew to over 270 employees and subcontractors – in a project that consumed almost 590,000 manhours. Almost all the staffing on the project was local, the company said.

“Being so well established in Zambia, we have a solid database of skilled artisans that we can draw upon for large projects like this one,” Opperman says. “The country has a good foundation of these trades, and we can select the most suitable profile of skills to match the project.”

He noted that the company is also able to optimise its local procurement through its network of reliable suppliers, while maintaining a strong cross-border supply chain for large and specialised equipment and components from South Africa.

In line with quality standards, each phase of the project involved the sign-off of both in-house and external quality control officers. This ensured all work was carried out in accordance with engineering designs and industry standard specifications before being certified ready for use.

E and I Zambia is also able to draw on the extensive technical capacity of South Africa-based EnI Electrical, an operating entity within Zest WEG.

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.

MIDEL ‘transforms’ safety at Glencore Mount Isa operation

MIDEL says it has helped improve safety at Glencore’s Mount Isa operations in north Queensland, Australia, following the introduction of its synthetic and biodegradable transformer fluid.

Operating since 1924, Mount Isa Mines is one of Australia’s largest industrial complexes extracting both copper and zinc-lead-silver, and contributing $1 billion to Queensland’s economy annually, according to MIDEL.

With over 3,000 workers operating in one of the world’s most expansive network of underground mines, as well as being Australia’s deepest underground copper mine at 1,900 m, safety at Mount Isa is paramount, MIDEL says. “With ore processed and smelted onsite too, the whole operation is power intensive and requires reliable, sustainable power infrastructure to maintain operations,” it added.

Glencore, as part of a risk mitigation program, identified mineral oil-filled transformers below ground at Mount Isa’s Enterprise mine as a potential fire risk, with the transformers flagged for further investigation.

Glencore invited MIDEL on-site to present options for reducing the risk posed by the transformers, and opted to retrofill the first transformer using MIDEL’s 7131 biodegradable, synthetic transformer fluid.

MIDEL 7131 has a high fire point (316˚C) and offers unrivalled fire safety benefits, according to the company, particularly for sites with enclosed spaces where smoke can be more deadly than the fire itself. “By retrofilling with a synthetic transformer fluid, the fire risk posed by the transformers was almost entirely eliminated,” MIDEL said.

Peter Ferguson, Electrical Superintendent at Glencore, said: “Despite MIDEL being more expensive than other transformer fluids, in the overall scheme of things, the difference was negligible particularly for such a vast improvement in safety.”

He added: “If we ever had to physically move the transformer this would be more costly and disruptive, so retrofilling with an oxygen-stable fluid gave us peace of mind.”

The benefits of switching to MIDEL’s synthetic ester include vastly reduced transformer fire risk, which means new units require no concrete blast walls, MIDEL said. This type of cost saving could extend into the millions of dollars, and transformers can be placed closer together, creating substantial substation space savings, too.

Additional operational benefits include improved moisture tolerance compared with that of mineral oil, which keeps the insulating paper in a better condition for longer and thus helps to extend transformer asset life. As MIDEL fluid is also fully oxygen stable, maintenance crews can handle it in exactly the same way as mineral oil, the company said.

Producers looking to improve their licence to operate can also leverage the environmental and sustainability benefits of synthetic ester, as it is fully biodegradable and non-toxic, MIDEL added.


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.

Zest WEG Group will continue to pursue Africa opportunities, new CEO says

Zest WEG Group’s new CEO, Siegfried Kreutzfeld, says the company’s ongoing growth plans will see it pursue further opportunities across Africa.

Kreutzfeld (pictured), who took on the CEO role in January, brings 40 years of service in the global WEG Group to the leading position in the South Africa business. He was most recently the Managing Director of WEG China.

He said: “WEG has a very simple strategy: we believe in continued growth on all continents. This is achieved by maintaining close relationships with all our customers and ensuring that we deliver quality products. We underpin all this by our high levels of service and support.”

Established in South Africa to create a strong national footprint, the Zest WEG Group has grown steadily into other Africa countries. With its responsibility for the sub-Saharan market, it operates branches in Ghana, Tanzania, Mozambique and Namibia. The group also has partners in countries such as Angola, Botswana, Zimbabwe, the DRC and Zambia.

“Many of our products are well established across the continent,” he said. “However, we believe there is growth potential with both mature products – such as low voltage motors, high voltage motors, and drives and switchgear – as well as with other products we manufacture locally such as transformers, motor control centres, panels and generators.”

Kreutzfeld said major opportunities exist with premium efficiency products across the range, including WEG IE3 motor and WEG CFW drives.

“Also key to the Zest WEG Group’s growth potential is our ability to offer a fit-for-purpose integrated solution,” he said. “This is available across all sectors, but especially in power generation, electrical infrastructure and mobile power and energy solutions. We will also be introducing WEG solutions for renewable energy applications.”

Zest WEG Group’s market offering is relevant across a broad sector of industries including mining, petrochemical, agriculture, water and wastewater, paper and pulp, sugar, and energy – including traditional coal fire power plants and renewable energy, the company 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.