Synthetic furfural analysis for transformer ageing

Measuring the furfural content with a high performance liquid chromatograph (HPLC) is an effective method, as it is helpful in tracing the aging of oil-immersed transformers. In this paper, recent laboratory research and field experiences on furfural analysis are introduced. And the depolymerization rate of cellulosic paper is studied in the laboratory, as well as the accumulation of furanic compounds in the same transformer. According to the laboratory research, the aging status of cellulosic insulating paper may be determined. Furthermore, combining the measurement of CO and CO₂ with dissolved gas analysis (DGA) the furfural content is developed, so the synthetic ageing diagnosis, based on those measured data, was improved also. Besides, the laboratory results are revised for field utilization, taking into account the differences existing between the laboratory condition and the field. Rather good agreement has been found when applying those improved results to many in-service transformers on site.