The first line of defence for MV systems

Tony Wills, application engineer at Megger, discusses the importance of using scanners to detect insulation faults.

The first line of defence for MV systems

If you work with medium-voltage (MV) switchgear or cables, a handheld partial discharge (PD) scanner provides a reliable way of detecting insulation faults before they progress to potentially dangerous failures. The scanners measure PD activity, a reliable early-warning indicator of insulation deterioration. Good scanners can use a range of internal and external sensors, which means that they are exceptionally versatile, and the best have intuitive software.

PD scanners are particularly suitable for use in transformer/distribution substations to make an initial assessment that the working area is safe, and for the inspection of switchgear. They are also ideal for surveying voltage and current transformers, terminations, bushings and other HV components, such as air-isolated busbars. In addition, the scanners can be used for making quick online PD measurements on cables.

The scanners detect radio frequency emissions produced by PD faults, so no direct connections are needed to the asset under investigation, which is a very important safety benefit. The asset remains energised throughout the test, without the need for disruptive outages. The latest scanners automatically evaluate the PD data to give a clear indication of situations where action is needed to ensure continued safe operation of the asset.

Failures in MV installations can be dangerous, often leading to long downtimes and high costs. Scanners detect potential weaknesses, allowing them to be resolved before they develop further. This means scanner users can make big savings and avoid service interruptions that might incur large penalties.

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