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

“The harsh environment of a coal mine required us to specially design a fit-for-purpose solution,” David Claassen, managing director at Trafo Power Solutions, says.

“The cast-resin dry-type transformer is ideal for the mobile arrangement as it is cooled without oil,” he explains. 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. The 1250 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 says. “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 that the transformer can withstand temperatures of up to 180°C. He notes 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 considering that 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 solid 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.

Dry-type transformer specialist Trafo Power Solutions has delivered transformers and other electrical upgrades for a global beer maker’s expanded facility in Gauteng.

In addition to the supply of three transformers, the customer was also looking for a partner who would interface with the suppliers of various aspects of electrical equipment, according to Trafo Power Solutions managing director David Claassen. Trafo has therefore interacted closely with the customer’s Europe-based engineering team on the one hand, and with local electrical contractors on the other.

Meeting high-pressure deadlines, three transformers were designed, supplied and commissioned. These included a 1250 kVA and a 1600 kVA unit – both with 11kV to 400 V capacity – as well as a 2000 kVA unit for 11 kV to 690 V application.

“These transformers all comply with the European Directive on Efficiency and are the lowest-loss dry-type transformers available,” Claassen says. “This was the customer’s specification, as they place strong priority on energy efficiency worldwide.”

Also, in the scope of work was medium voltage switchgear, including two ring-main units (RMUs) with one a three-way and the other a four-way.

“We modified the RMU’s in line with the customer’s requirement, including a battery-tripping unit (BTU) on each,” he says. “This ensures there is power available regardless of the condition of the circuit breaker.”

As a brownfield project, there was considerable adaptation of design to suit the plant configuration. Instrumentation was located on a raised base, for instance, where voltage transformers and current transformers were installed for monitoring each RMU.

“We also supplied three very specialised distribution boards (DBs) between the low voltage transformers and the new sections of the plant and new brewhouse,” he says. “This non-standard design has a modular type assembly conforming to EIC 61439 and EIC 61641.”

This provides the highest level of safety and can be supplied by only a few manufacturers in South Africa. The DBs, which are fully-tested for IEC 61641 (Internal Arc Fault), incorporate 2500 Amp incomers, distributing through various feeder circuits to the rest of the plant. Two of the DBs are 400 V and the third is 690 V.

“Another non-standard aspect of the DB supply was its Form 4A design, so that each compartment is separate,” Claassen says.

He highlighted the company’s in-house capacity to provide complete solutions within tight deadlines. In this case, the design, manufacture, delivery and commissioning were achieved in just three months. Installation was also co-ordinated with plant shutdown schedules to avoid costly downtime.

“We develop non-standard solutions where these are required, and take responsibility for integration, compatibility, quality and timeframes,” he says.

Trafo Power Solutions, experts in dry-type transformers, has recently completed a contract as part of a significant upgrade at a Mpumalanga coal mine.

This involved the design, supply and installation of two 200 kVA – 22 kV to 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 contract demonstrated our application engineering capability, and our experience in co-ordinating our solution within a larger project,” Claassen says. “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.

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

Claassen emphasises that the absence of oil has advantages for safety, as the possibility of oil igniting is removed. The units can also be well protected against fine airborne coal dust. An added advantage is environmental, as there is no chance of an oil leak contaminating the ground or water.

The uptake of dry-type transformers in South Africa is now well beyond ‘niche’ applications, with local specialist Trafo Power Solutions installing a range of sizes across various sectors.

“In recent months, we have been involved in projects with small 50 kVA low voltage lighting transformers, right up to 4,5 MVA medium voltage customised units,” says David Claassen, managing director of Trafo Power Solutions. “These have been installed in healthcare facilities, commercial buildings, educational institutions, mines and data centres, as well as at solar energy plants.”

Among its recent contracts, the company has supplied a number of lighting transformers. It has also provided outdoor instrument transformers to facilitate measurement of voltage on overhead lines. These cast-resin voltage transformers (VTs) typically have 33 kV, 22 kV and 11 kV primaries with 110 V secondaries with between 50 VA and 500 VA burden.

“These are substantially lighter than their oil-cooled equivalents, and are, of course, safer due to the absence of oil in their design,” he says.

In the mining sector, a recent contract was the installation of 200 kVA dry-type transformers. This is often a corrosive environment in terms of water and dust, so a high ingress protection (IP) rating was applied. Claassen adds that a range of materials and paint can also be specified by the customer to further withstand corrosion.

Data centres are a fast growing aspect of the country’s digital economy, and Trafo Power Solutions is supporting this segment with its cast-resin transformers. It recently delivered and cold-commissioned two 2 MVA units for a data centre in Cape Town.

“These facilities obviously require the highest levels of reliability and protection from their electrical and electronic networks,” he says. “The windings and core of our units were designed for a K factor of 13, given the high non-linear load. An electrostatic shield was also installed, along with surge protection of the highest order.”

He notes that there was substantial time pressure on completing the contract, but flexibility and responsiveness that Trafo Power Solutions offers ensured on-time delivery.

At three small-scale solar plants, Trafo Power Solutions is providing three 800 kVA transformers which will step up power from 400 V to 22 kV. These applications involve a solar inverter for the 100% non-linear load, as well as an electrostatic shield between the primary and secondary windings.

Claassen emphasises that the business prides itself on the level of application engineering for each customer’s specific requirements.

“We understand what we are supplying and the risks faced by the customer and we design the solution accordingly,” he says. “Industry is certainly showing their faith that dry-type transformers can be applied in a growing range of applications.”

Dry-type transformer specialist Trafo Power Solutions has supplied four purpose-designed units to the University of Witwatersrand (Wits) as part of the institution’s electrical infrastructure upgrades on both its Braamfontein and Parktown campuses.

According to Trafo Power Solutions managing director David Claassen, Wits decided to replace the original oil-cooled transformers with the dry-type, cast-resin transformers. These are safer and more environmentally-friendly due to the absence of oil in the system.

“The high safety factor associated with dry-type transformers has an impact on flexibility and cost,” says Claassen.

“The user can be more flexible in terms of where the units are installed, as they can be placed indoors, in basements or in other confined spaces for convenience. This also means the cost of building special infrastructure for outside installations – a requirement of oil-cooled transformers – can be avoided.”

He highlights that Trafo Power Solutions was closely involved from the proposal stage in this project, providing the necessary application engineering to ensure the appropriate design for the generator company responsible.

“As specialists in transformer technology, our expertise is not just in the product that we are installing but also in understanding the bigger picture – the infrastructure requirements as a whole,” he says. “Any successful installation is a close collaboration between Trafo Power Solutions, the engineering company, the consultants and the contractors to ensure that the final result is fit for purpose and serves the customer’s need.”

With the growing installed base of dry-type transformers in the global marketplace, the price differential between this design and that of conventional transformers has become insignificant. This has opened the door for users to take advantage of the numerous benefits of dry-type transformers, he says.

Data centres are energy hungry beasts that operate with a high power demand, and it is important that the most appropriate transformers with the requisite protection devices are specified for this robust application.

David Claassen, managing director of Trafo Power Solutions, explains that it is important to understand data centre applications and especially the load which the transformer will be supplying as well as the type of switchgear that will be feeding it. “This,” he says, “is important from a voltage transient perspective.”

Trafo Power Solutions recently supplied two 2000 kVA 11,6kV/415V dry-type transformers to a large data centre in the Cape Town. Manufactured under stringent quality control conditions at Italian transformer OEM TMC, these specialised units are low loss transformers which conform to the European Directive EU 548-2014 and will provide greater energy savings in this application.

“Dry-type transformers are ideal for data centre applications, and correct upfront design played a role in ensuring that these transformers will meet the application requirements,” Claassen says.

The design was important in terms of the transformers windings as well as the core changes in this type of application where there is a high percentage of non-linear or harmonic load. He says that in this case the design K-factor for these transformers is 13.

These transformers were designed differently to a standard distribution load transformer and have an electrostatic shield which diverts noise to ground as well.

Trafo Power Solutions was able to assess the application requirement and provide a solution that could be delivered within a tight delivery time frame, which was an added advantage to the end-user.

When a mining company in KwaZulu-Natal experienced a transformer failure recently, it was hoping for a quick solution. The mine got one from dry-type transformer specialist Trafo Power Solutions, who took just five weeks to design, build and deliver a non-standard cast-resin replacement.

“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,” says David Claassen, managing director of Trafo Power Solutions.

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

Claassen notes it is not uncommon for transformer replacements of this scale to take anything from 12 to 14 weeks, so the rapid turnaround time by Trafo Power Solutions was 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.

“We are always willing to step in when a user has an urgent requirement, and to propose innovative solutions that meet customers’ priority needs,” says Claassen.

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. To meet this demand, Trafo Power Solutions works in close collaboration with established and well-resourced manufacturing partners in Europe to source tailored designs that meet customers’ exacting specifications. With its South Africa-based expertise and long experience all over Africa, Trafo Power Solutions provides users with peace of mind by ensuring ongoing after-sales service.

Africa continues to follow the global trend in taking up dry-type transformer technology, owing largely to its enhanced safety levels and lower maintenance requirements.

According to David Claassen, managing director of local dry-type transformer specialist Trafo Power Solutions, the growth of this market segment continues to extend the capacity of these units, which are now available in outputs up to 25 MVA.

“Africa has also been an enthusiastic market for the trend towards modular installations in applications like mining, water treatment and power generation. The safer, oil-free design of dry-type transformers allows them to be readily placed in modular substations, in close proximity to other equipment and personnel,” Claassen says.

In a partnership that will further boost the accessibility of dry-type transformer solutions across Africa, Claassen says that Trafo Power Solutions has now formalised its close collaboration with leading Italy-based manufacturer TMC Transformers.

“TMC is one of two leading designers and manufacturers of dry-type transformers,” he says. “After working with them for the past couple of years, we have signed an exclusive engineering partnership agreement to supply and service sub-Saharan Africa.”

Claassen emphasises the close alignment between the solution-focused approaches of the two companies. “We work together at all stages of each project from application engineering through to design, manufacture and customer support,” says Claassen.

TMC Transformers business development manager Roberto Deri highlights that the European company does not only manufacture standard products, but is driven by customers’ specific needs and project applications.

“This is the reason we are highly selective in our partnerships, as those companies with whom we work, such as Trafo Power Solutions, must have the engineering and design expertise to work closely with us on a technical level,” says Deri. “In this way, we fully leverage the capacity of our state-of-the-art design and manufacturing facility.”

The 25,000 m2 facility situated in Busto Arsizio near the Italian/Swiss border employs over 100 highly skilled technicians and professionals, and produces on average 16 complete transformer units a day.

Deri notes that TMC’s owners have over three decades of experience in this field, having built up their previous transformer business into a market leader worth €200-million before it was sold to a leading global OEM.

“Having purchased the TMC facility in 2017, the vision of our ownership and management team is to grow this business into a global force,” he says. “The company is already well on its way toward this goal, with rising global sales underpinned by a strong reputation for quality engineered products backed by solid technical support.”

Deri was recently in Johannesburg to exhibit – jointly with Trafo Power Solutions – at the well-attended Power & Electricity World Africa at Sandton’s Convention Centre.

Four dry-type transformers from Trafo Power Solutions have been proving their worth on a mobile process plant on a Sierra Leone mine since last year; so successful have they been that the customer has ordered six more for its recent Phase Two upgrade.

“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,” says Trafo Power Solutions managing director David Claassen. “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. 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 six metre 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,” says Claassen. “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. 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.

“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,” he says. “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.