A new measurement method of DC corona-discharge characteristics using repetitive ramp and triangular voltages

DC corona discharges are widely used in industrial applications. The electrical characteristics of these discharges (e.g., the corona onset voltage, the voltage at which the corona discharge transfers its mode, the appearance of corona discharge modes, the average current-voltage (I–V) characteristics, and the corona discharge hysteresis) are usually investigated via procedures in which the DC voltage is varied step-by-step. However, these procedures have limitations. For example, it is difficult to determine the voltage at which the transition from one corona discharge mode into another mode occurs. The procedures are also time-consuming because the voltage and corresponding current waveforms must be monitored step-by-step to sweep the corona discharge I–V characteristics and determine the corona mode transition points. To address these problems, we have introduced repetitive ramp and triangular voltages generated using a high voltage amplifier rather than DC voltages to investigate the I–V characteristics of corona discharges. Using ramp voltages in our experiments, the I–V characteristics of both positive and negative corona discharges were determined. The I–V characteristics obtained using the ramp voltages were then compared with those measured laboriously step-by-step by varying the DC voltage. Additionally, time-resolved corona discharge images of the ramp voltages in our experiments were captured using an intensified charge-coupled device (ICCD) camera. These images illustrated how the discharge modes of the positive and negative coronas varied with increasing applied voltages. We also measured the hysteresis of the positive and negative corona discharges using repetitive triangular voltages, which represent a modified version of the ramp voltages.