Using High-Precision Multimeter Digitizer for High Short-Circuit Current Calibration

The calibration of transient current sensors is fundamental for the reliability of high currents short-circuit tests. The test can be performed with prospective or withstand current, and in both cases, the dynamic behavior of the current sensors has to be investigated, due to their influence on the scale factor (SF) value. The requirements of the IEC 62475 standard can be achieved with a calibration in transient conditions, performed with an approved reference measuring system. In this paper, a more accurate measuring system is presented, for the improvement of the Istituto Nazionale di Ricerca Metrologica high transient current measuring capability. The result is achieved by analyzing the performance in digitalization of a commercial Keysight (former Agilent) multimeter 3458A, with a custom algorithm that can also perform the calculation of Joule integral ( $I^{2}t$ ) on a given amount of time along the acquired signal. The objective of the research is the realization of a measurement system with an uncertainty compatible with the test laboratory requirements, both for the determination of SF and evaluation of the performance in the measurement of $I^{2}t$ in the device under calibration.