Electrical Power & Protection


Minimal maintenance for dry-type transformers

September 2024 Electrical Power & Protection

With minimal levels of maintenance needed, dry-type transformers offer reliable performance over lengthy lifespans, with few of the risks and hazards associated with oil cooled transformers. According to David Claassen, managing director of dry-type transformer specialist Trafo Power Solutions, the fact that these units are air cooled means much of the limited servicing required involves maintaining clear air channels, which can be compromised by the accumulation of dust layers.

“To allow for the transformer to cool effectively, it is important to regularly check that there is not an excessive buildup of dust on or around the transformer,” Claassen explains. “Depending on the ambient conditions, dust can build up in these confined spaces and start to impede the free flow of air.”


Dust accumulation can be easily addressed by using a leaf blower or similar appliance to remove the dust from the transformer. This method quickly disperses the dust, leaving the surfaces clean and allowing for more efficient heat transfer. Claasen explains that a regular maintenance schedule is especially vital in applications such as coal mines, where there are often high dust levels. Where dust layers prevent adequate cooling, the transformer could run at temperatures higher than its design parameters. This degrades the insulation material faster and could significantly reduce the unit’s lifespan. Even in the event that a completely sealed enclosure is used (≥ IP55), it is possible for dust to enter the enclosure while the doors are opened or in cases where the doors are left open accidently.

“It is also important to check that the temperature probes are measuring accurately,” he notes. “This ensures that any unexpected temperature rise will trigger the necessary alarm, and that the feed-in circuit breaker to the transformer is tripped in the event of overheating.”

Terminals on the transformer should be checked, as it is possible for these connections to loosen due to vibrations or other factors. This is a simple process of checking the torque on these connection points, as any looseness could lead to partial discharge, heat buildup and further damage.

To guide the customer in their maintenance planning, Trafo Power Solutions provides a maintenance manual with each installation. This details the required frequency of service interventions, which in a clean indoor environment is usually only once a year. Under dusty conditions that might be encountered outdoors, the maintenance should normally be conducted every six months.

“Beyond our standard requirements, we also provide our customers with site-specific servicing guidelines that suit their application and environment,” says Claassen. “Indeed, we can provide the actual maintenance service should the customer require, ensuring that they have access to a detailed log of results and recommended interventions.”

He explains that while the maintenance tasks are generally straightforward, the transformer does need to be de-energised by a qualified technician before this work is conducted. This ensures the necessary compliance to regulations relating to medium voltage equipment, including procedures for lockout and isolation.

“A key advantage of dry-type transformers is that this maintenance is relatively quick and simple compared to oil-cooled transformers,” he notes. “A key difference in the servicing of these two technologies is that conventional oil-cooled transformers require oil samples to be taken regularly and sent away for testing and analysis. This is a costly and time-consuming addition to their total cost of ownership.”

For more information contact Trafo Power Solutions, +27 11 325 4007, info@trafo.co.za, www.trafo.co.za




Share this article:
Share via emailShare via LinkedInPrint this page

Further reading:

Power supply with scalability optimised
Schneider Electric South Africa Electrical Power & Protection
Schneider Electric has introduced the Easy UPS 3-Phase Modular to the South African marketplace. This robust uninterruptible power supply (UPS) is designed to protect critical loads while offering third-party verified Live Swap functionality.

Read more...
Prioritising arc flash safety
Comtest Electrical Power & Protection
Comtest has developed a range of thermal imaging and wireless testing tools from Fluke, designed to ensure safety is the top priority for engineers working in potentially dangerous arc flash zones.

Read more...
Taking African mining organisations to net zero
Electrical Power & Protection
Danfoss recently participated in the Electra Mining Africa 2024 exhibition, highlighting its latest innovations, sustainable solutions and commitment to supporting the African mining industry’s journey toward decarbonisation.

Read more...
Harness the power of the sun
Conical Technologies Electrical Power & Protection
In today’s rapidly evolving world, sustainable energy solutions are more critical than ever. The PLANET BSP-115HP-5A Solar PoE Switch is a perfect blend of cutting-edge technology and green energy, designed to empower your network with solar power.

Read more...
RS is your trusted partner in the mining industry
RS South Africa Electrical Power & Protection
The mining industry is facing significant challenges. Success in such an environment requires partnering with a supplier that is collaborative, flexible and forward-thinking. RS stands as the ideal partner to help businesses in the mining sector achieve their goals, while saving time and money.

Read more...
All aboard the solar rollercoaster ride
Schneider Electric South Africa Electrical Power & Protection
The South African solar energy market has certainly gone through an exciting time, marked by surging demand, fluctuating prices, and changing government policies. After last year’s mad scramble, 2024 heralded a normalised energy landscape, albeit with a mixture of distributed energy resources such as solar PV.

Read more...
The potential of green hydrogen
Schneider Electric South Africa Electrical Power & Protection
A recent report published by ScienceDirect, highlights two storage technologies: battery storage and green hydrogen storage. Whilst green hydrogen is well known as an energy source, it might come as a surprise to some that it is also an extremely efficient storage solution.

Read more...
New power distribution switchboard range
Schneider Electric South Africa Electrical Power & Protection
Schneider Electric South Africa has unveiled its latest PrismaSeT range of new-generation power distribution switchboards, which offers unrivalled modularity and minimum assembly time, even for the most demanding configurations.

Read more...
Ensuring industrial safety in mines with earth leakage protection
NewElec Pretoria Electrical Power & Protection
Mining operations are inherently risky due to the hazardous environment and complex machinery involved, making the implementation of earth leakage protection systems critical to ensuring the safety of miners and the integrity of equipment.

Read more...
Advanced harmonic power analyser
Electrical Power & Protection
Industries with high motor usage such as milling, bottling plants, plastic manufacturing, and refrigeration often struggle with electrical inefficiencies that lead to increased costs and potential equipment damage. Many of these businesses are unaware of the impact of electrical harmonics – additional, unwanted frequencies created by nonlinear loads like computers,variable speed drives and LED lighting.

Read more...