From blackout to Partial Discharge Monitoring at Madrid airport

Madrid, Spain

A one-hour blackout at Madrid-Barajas Airport revealed insulation defects in a newly installed 45 kV cable. Partial Discharge (PD) Monitoring using BlueBox Technology identified critical faults, guided targeted repairs, and restored power reliability in one of Europe’s busiest airports.

Introduction

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Madrid-Barajas Airport is located in the northeast of Madrid, in the Barajas district, 12 kilometers from the city center. It is the busiest airport in Spain in terms of passengers, cargo, and operations. It ranks fourth in Europe and twelfth globally by passenger volume, with over 45 million travelers passing through its facilities each year—approximately 123,000 per day.

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Power supply problems due to insulation defects

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At around 11 p.m. on August 15, 2009, an electrical fault occurred at Madrid-Barajas Airport, resulting in a one-hour power outage. Investigations conducted by AENA (the airport manager), an external company, and the Polytechnic University of Madrid concluded that the fault was caused by partial discharges (PD), which led to insulation failure at a transformer connection. The defect originated during installation due to an error made by the technician while mounting the accessory.

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Initial measurements

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To prevent similar incidents, AENA decided to carry out targeted measurements to assess the condition of the cable system’s insulation. These measurements were performed using portable equipment based on BlueBox Technology, which detected several PD sources in different accessories. The affected components were repaired and re-measured to confirm successful restoration.

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Following this, AENA installed a permanent monitoring system on one of its most critical cables—a newly installed 45 kV double-circuit cable, 4,135 meters long, featuring four cross-bonding points and several straight joints.

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Commissioning of the cable

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To commission the 45 kV double-circuit cable, a test was conducted using a Very Low Frequency (VLF) generator at 1.2 times the nominal voltage. After the test, BlueBox Technology was used to verify that the cable system was free of PD activity.

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Continuous monitoring using BlueBox Technology

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After the commissioning test using VLF confirmed the absence of PD sources, the continuous monitoring system based on BlueBox Technology was activated.

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After a few days of data collection, multiple PD sources were detected and located at the joints of the newly installed cable. These PD sources were monitored over several more days to evaluate their criticality.

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The graph shows the location of PD sources on the vertical axis and time on the horizontal axis. Blue indicates low activity, while yellow to red indicates higher activity.

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After nine months of monitoring, a total of ten PD sources caused by main insulation problems were located. These sources showed high amplitude and PD rate, making them likely to cause a breakdown in the short term.

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The image shows a PD pattern characteristic of the internal defect found in this installation. Internal PD defects progressively damage the insulation condition of the cable and can lead to failure.

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Conclusions

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Using BlueBox Technology, multiple defects were detected at the joints of the cable system. None of these PD sources were identified during the initial commissioning test using other technologies.

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Since the cable system was entirely new, the PD sources were likely caused by errors during the installation and assembly of the circuit. BlueBox Technology enabled the measurement of PD amplitude and rate, allowing for accurate diagnosis of insulation condition and planning of repairs. After repairs were completed, follow-up measurements confirmed that the cable system was free of internal PD activity.