Acoustic insulation analyzer for periodic condition assessment of Gas Insulated Substations

A new instrument based on acoustic methods has been designed which is offering non-invasive condition assessment of Gas Insulated Substations (GIS) during normal service. The instrument will be able to reveal many of the defects resulting in breakdown of GIS and will in general have a significant cost benefit. Based on results from several years of field experience it has been confirmed that the recordings generated by this instrument make it possible to detect, locate and recognise the most common defects such as moving particles, particles on spacers, partial discharges from protrusions and loose shields. The detected signatures from the defects may also be used for risk assessment of the GIS. The paper describes the technical background of the instrument and illustrates how acoustic signals from different types of flaws are presented by and can be recognized from the instrument. Thereby, the instrument can be used efficiently by maintenance people without being experts in acoustics.