Improvement and uncertainty evaluation of a 1 MV lightning impulse measurement system

This paper focuses on development of an existing 1 MV lightning impulse (LI) measuring system as part of European project for i.a. LI calibration capabilities development. After carefully characterization of the original LI divider a new low voltage arm was designed and built with e.g. improved shielding and also RC circuits for compensating the detected drift in the step response. With the compensation step response was successfully corrected resulting in clear improvements in LI time parameter measurements. However, persistent high frequency noise was present in the step response complicating further fine-tuning of the response. The noise could not much be improved at least partly due to non-optimal damping resistor structure, which is difficult to improve afterwards. After the improvements an extensive uncertainty evaluation was carried out for the original system as well as for two versions of the improved system.