Traceability and Mutual Recognizability of Impulse Voltage Measurements Round Four

摘要

This report presents the results of the fourth round of a worldwide lightning impulse comparison measurement. Seven laboratories out of 26 made the comparison measurements on the fourth round. The participating laboratories compared their impulse voltage measuring system with the circulating reference measuring system at voltage levels of 80, 160, 240, 320 and 400 kV. Three impulse shapes were used, i.e. full smooth lightning impulses with either short (0.84-0.95 microseconds) or long front (1.45-1.56 microseconds), and chopped impulse with time to chopping of 0.5-0.6 microseconds. The impulse with long front time was used for generating the chopped impulse. Impulse peak value (Up) and time parameters according to IEC 60060-1 were compared (T1, T2 and Tc). In addition the participants made a comparison between a circulated impulse voltage calibrator and their own impulse measuring instrument or impulse calibrator. The comparison was made using two lightning impulse (0.84/60 and 1.56/60) and two switching impulse (20/4000 and 250/2500) shapes. Voltage level ranged from 50 mV to 1000 V. Measured parameters were according to IEC 60060-1; Up, T1 and T2 were compared in lightning impulse measurements, and Up, Tp and T2 in switching impulse measurements.