The paper details the ways in which waveform effects in electrostatic precipitators (ESPs) are modeled. The effects of waveforms on particle charging, space charge corona suppression, and sparking are examined. The paper shows how the models extend these results to the case of intermittent energization. Electrical energization waveforms were discovered to have an unexpected large role during the development of two ESP programs, ESPM and ESPVI 4.0. The model that predicted laboratory voltage/current curves superbly gave unacceptably high current densities for large scale ESPs. This is primarily due to the waveforms: pure dc in the laboratory and pulsating dc in the field.