A Complete Transformer Monitoring Solution with Advanced APM, RM EYE

Overview

On 20th March 2025, the SGT3 power transformer at the North Hyde substation suffered a catastrophic failure. This resulted in a massive fire and complete power loss, affecting over 71,655 customers at the world’s busiest airport, London Heathrow.

An investigation conducted by NESO published its findings in the North Hyde Review Final Report, revealing that moisture ingress in the C-phase high-voltage bushing was the cause. The report also showed the presence of early warning signs as far back as 2018 and classifying bushing moisture level as a Category-1 fault under the National Grid Electricity Transmission’s guidelines. However, corrective maintenance was deferred multiple times, and no continuous bushing monitoring system was in place.

In this case study, we examined how Rugged Monitoring’s solutions, if installed, may have predicted and prevented this catastrophic event.

The Challenge

The North Hyde substation solely relied on reactive maintenance, offline diagnostics, and manual interventions, which resulted in:

Missed Early Warning Signs

Lack of systematic workflow between manual data and scheduled maintenance.
Lack of Continuous Monitoring

No real-time monitoring of critical parameters such as bushing or PD.
No Integrated Risk View

Without data-driven analytics, there is no real-time view of an asset’s compounded risks.
Deferred Maintenance

Limiting maintenance to only reactive interventions became insufficient over time.

The Rugged Monitoring Solution

Rugged Monitoring has previously implemented its Enterprise APM Suite, RM EYE, to enable an intelligent, digitized substation environment. For this scenario, our suggested ecosystem would have been:

Advanced Bushing Monitoring

For continuous measurement of critical bushing outputs such as dissipation factor (tan delta), capacitance, and partial discharge.
Partial Discharge & Arcing Detection

Real-time monitoring with IIoT partial discharge system that de-escalates faults before they become failures.
Enterprise APM Suite, RM EYE

For centralized condition monitoring using AI-driven predictive intelligence.

The Outcome

Our solutions would have achieved the following quantified impact for the North Hyde substation, in a preventive scenario:

Avoided outage of 71,000+ customers, including critical transport.
Prevented transformer replacement cost: ~GBP 80 to 100 million.
Eliminated fire-related damage and environmental hazards.
Improved maintenance efficiency through automation and risk-based prioritization.

The North Hyde incident serves as a critical reminder of why continuous monitoring and predictive intelligence, such as RM EYE, are essential for ensuring reliability, safety, and public confidence in power systems.

Connect with Our Expert

Have questions or need more information? Reach out to us for reliable Rugged Monitoring solutions.