Influence of Combination Wave Generator's Current Undershoot on Overvoltage Protective Characteristics

Evaluation of the ability of equipment to withstand a wide variety of surges that can be expected to occur in low-voltage ac power systems, or of the performance of surge protective devices (SPDs) in dealing with this variety of surges, can be facilitated by a reduction of the database to a few representative stresses. IEEE Std. C62.41.2 and IEC Std. 61000-4-5 define the combination wave surge as a standard surge-testing waveform. However, these standards define different tolerances regarding the waveform undershoot of a short-circuit current surge delivered by the combination wave generator (CWG). In this paper, the influence of CWG short-circuit current undershoot has been analyzed for the case of one-stage protection with SPD located at the service entrance of the building. Simulation results for the model of the observed system in the Alternate Transients Program/Electromagnetic Transients Program and MATLAB, with experimental verification show that the short-circuit current undershoot of CWG has an influence on maximal values of voltages across load and energy deposited in SPDs.