IEC 61083-1-2021 Instruments and software used for measurements in high-voltage and high-current tests – Part 1: Requirements for instruments for impulse tests

IEC 61083-1-2021 Instruments and software used for measurements in high-voltage and high-current tests – Part 1: Requirements for instruments for impulse tests. 5 Calibration and test methods 5.1 Calibration of scale factor and time base The scale factor and time base shall be determined by either – impulse calibration (5.2) with two waveforms covering the nominal epoch, or – step calibration (5.3) with test of scale factor constancy (5.4) and calibration of time base (5.5), or – an impulse calibration (5.2) with one impulse waveform within the nominal epoch with the constancy of scale factor test (5.4). 5.2 Impulse calibration Impulse calibration is the reference method to establish the impulse scale factor of approved digital recorders. It is also the reference method to determine the errors of the impulse time parameters caused by the digital recorders. Requirements on reference calibration impulses for calibrating approved digital recorders are given in Table 2. The wave shapes shall be chosen from Table 2 according to the type and polarity of the high-voltage or high-current impulses that the digitiser is approved to measure. The uncertainties of the peak value and time parameters of the applied calibration impulses shall be within the limits given in Table 2, and the actual values shall be entered in the record of performance. The number of calibration impulses to be applied shall be sufficient for obtaining sufficiently low type A uncertainties for all relevant parameters. The impulse scale factor is the ratio of the peak value of the input calibration impulse and the peak value of its corresponding impulse recorded by the digitiser. The assigned impulse scale factor is the mean of impulse scale factors determined from a set of individual calibration impulses. The error of a time parameter is the mean of the time parameter errors determined from individual calibration impulses. This impulse calibration shall be made in each range of each channel that the digitiser is approved for use in impulse tests. 5.3 Step calibration The step calibration is the alternative method for establishing the impulse scale factor of an approved digital recorder. To qualify an approved digitiser for measuring impulse time parameters, the scale factor constancy test specified in 5.4 and the calibration of time base as specified in 5.5 shall also be performed if the impulse calibration as specified in 5.2 is not performed. A direct voltage V CAL , with an uncertainty less than...