Study on On-Line Monitoring of Dielectric Loss Factor for Insulation on Synthetical Relative Idea

This paper introduces absolute measuring method, simple relative method in common use and new synthetical relative method (SRM) ^[1] on on-line monitoring. From principle of method and applied effect in practice, SRM can settle stability and reliability problem in two foregoing methods to a certain extent But the method need be further improved in three aspects. Firstly acquirement of complete period or frequency is the basis of signal processing. Combination of multi-wavelet transform having excellent de-noising ability and auto-adaptation periodic sampling algorithm is feasible. Secondly, variation of environment factor is instantaneous. This paper put forward synchronously measuring idea to deal with miscarriage of justice possibly brought by SRM. At last, according to long-term monitoring, inverse relation of monitored parameter fluctuation of different equipments is existent. On maximal insulation factory-ageing curve, a symmetry transformation of measured insulation parameter can effectively remove this inverse relationship on monitoring. At the same time, insulation ageing trend is reserved also. The experiment results show that the improved SRM can powerfully reduce measuring error and accurately judge the equipments´ state.