A Study of DC Switching Electric ARC Characteristics for Low Voltages

Aims: The purpose of this paper is to investigate the DC electric arc characteristics for low voltages. And explore the relationship among arc time, arc voltage and arc current. Study Design:  The experimental setup mainly consisted of a switch contact pair, variable resistive load, and a variable power supply. An oscilloscope was used to collect the voltage variations of the switch and the load. The voltage variation data were used to do further analysis. Place and Duration of Study: Department of Physics and Electronics, University Of Kelaniya, Sri Lanka between September 2021 and May 2022. Methodology: Voltage variations between the contact pair and the load voltage were measured using an oscilloscope for both switching on and off operations. The experiment was performed for four voltage levels; 60 VDC, 80 VDC, 100 VDC, and 120 VDC. For each voltage level, four load conditions were tested. Therein, a total of 16 different conditions were tested. Five tests were done for each condition. The average values were taken for analysis. Conclusion: When the switch contacts start to separate, the arc voltage must reach the arc starting voltage to form an arc. Moreover, according to the supply voltage and current, there is always a maximum voltage value that arc can reach, which is less than the supply voltage (arc ending voltage). After the arc was formed in DC systems, the arc voltage variation with time can be modeled using the trigonometry tan function.