International comparison of HV impulse measuring systems

The authors studied the agreement between laboratory measurements of full and front-chopped lightning impulses at four national laboratories. First, some general information on how standards are maintained and disseminated is presented together with a brief review of the requirements for HV impulse measurements. Then, the comparative measurements made in the four national laboratories are presented and the relative differences are reported. Comparative measurements can be made for full standard lightning impulses to within 1% for crest voltages and to within 5% for front times. These uncertainties may be adequate to allow the calibration of industrial measuring systems to within 3% for crest values and 10% for front times, as is required by the relevant standards, provided the systematic errors of the reference system are sufficiently small