Effect of Sampling Rate and Sensor Bandwidth on Measured Transient Signals in LV AC and DC Power Systems

Impulsive transients in power systems can stress the state of electrical insulation of equipment. Knowledge of signal characteristics is of paramount importance to accurately assess their impact on electrical insulation. This paper investigates the effect of sampling rate and sensor bandwidth on capturing high-frequency transient disturbances and their characteristics in laboratory-scale LV AC and DC systems to increase the understanding of their impact on electrical insulation. Two measurement systems of different bandwidths and configurable sampling rates, up to 500 kS/s and up to 250 MS/s, have been used in parallel to capture and compare the high-frequency transient phenomenon in voltage signals following DC series electric arc faults and the AC output of a bi-directional power converter. The presence of unknown high-frequency transient signals of magnitudes more than 10% and more than 600% with respect to the considered voltage of the system were found to exist in AC and DC recorded signals, respectively. Three dependency curves relating the maximum voltage, the rate-of-rise, and the pulse duration of the transients to different sampling rates are experimentally established to provide an improved appreciation of transient characteristics and a better correlation of their impact on the electrical insulation systems.