Long term leakage current measurements in the field: Techniques to overcome the noise and data size problems

The performance of outdoor insulation is strongly correlated to surface electrical activity, experienced in service conditions. Leakage current is probably the optimum tool, in order to monitor the electrical phenomena experienced. Field monitoring offers a view of the actual phenomena experienced. Two are the main issues concerning the efficiency of a field monitoring system: the influence of noise and the accumulated data size. In this paper, a number of 4856 waveforms are investigated. The waveforms are recorded on porcelain and coated insulators in a 150kV coastal HV substation. The influence of field noise is investigated. Four techniques that can be hardware implemented are evaluated towards diminishing the noise and data size problems. The study objective is to incorporate the results in the development of an improved leakage current monitoring system, capable of operating in the field.