| Company | BAA Airports |
| Location | London Heathrow Airport |
| Timeline | 1991 onwards |
| Project Overview | MIDEL-filled transformers helped Heathrow Airport overcome overheating risks caused by dust, delivering safer and more reliable power for critical operations. |
| Product | Midel Ester Transformer Fluid |
London Heathrow Airport is one of the busiest transport hubs in the world, handling millions of passengers every year. Behind the scenes, a vast network of electrical infrastructure keeps everything running, from baggage systems to lighting and terminal services.
At the heart of this system are distribution transformers, responsible for delivering reliable power across the airport. Originally, Heathrow relied on cast resin transformers, which were seen as a safe option for indoor environments. However, as the airport evolved, so did the challenges.
One unexpected issue came from the airport’s own activity.
Near the baggage handling areas, constant movement of luggage released large amounts of fabric dust into the air. Combined with general dust from passengers and staff, this created a difficult environment for electrical equipment.
The cast resin transformers faced several problems:
Dust build-up on coils, driven by airflow and static fields
Increased risk of overheating, as layers of dust acted like insulation
Potential electrical issues, affecting reliability
High maintenance demands, requiring regular cleaning
Attempts to solve the problem by adding filters only made things worse. The filters quickly clogged, restricting airflow and increasing maintenance needs even further.
It became clear that a different approach was needed—one that could handle the dusty environment without constant intervention.
BAA Airports began looking for an alternative to cast resin transformers.
Fluid-filled transformers were identified as a better option, as they are enclosed and less affected by airborne contamination. However, traditional mineral oil could not be used due to its lower fire safety, which is a critical requirement in a busy public space like an airport.
After consulting with M&I Materials, the decision was made to switch to MIDEL ester fluid-filled transformers.
These transformers offered a key advantage:
They are fully sealed, preventing dust from settling on internal components
They do not generate external static fields, reducing the attraction of airborne particles
They provide high fire safety, making them suitable for indoor and public environments
Switching to MIDEL-filled transformers brought immediate and lasting improvements:
Reduced Overheating Risk: Sealed design prevents dust build-up on critical components
Lower Maintenance Requirements: No need for frequent cleaning or filter replacements
Improved Reliability: Consistent performance in a challenging, dust-heavy environment
Enhanced Fire Safety: Suitable for high-traffic public spaces
Operational Efficiency: Less downtime and fewer maintenance interventions
The success of the MIDEL solution was clear. The new transformers performed reliably in areas where dust had previously caused issues, eliminating overheating risks and significantly reducing maintenance workloads.
So effective was the change that during the development of Terminal 5, MIDEL-filled transformers were selected again, demonstrating confidence in the solution and its long-term performance.