3. In-service monitoring

Over the lifetime of a device, mains power surges can cause partial discharges, leading to the generation of gases and other soluble or insoluble by-products. Similarly, prolonged local heating can lead to impregnant degradation, and the production of by-products. The ageing of a device can be monitored by regular analysis of the state of the liquid.

Analysis of dissolved or free gases is mainly used for power transformers. In this particular case, a guide (IEC 60599) has been drawn up for the interpretation of these analyses. Diagnosis is based on the reports C ₂ H ₂ /C ₂ H ₄ CH ₄ /H ₂ and C...