Improved measurement of resistance and calculation of arc power in fusion welding

Abstract

We reported a new method based on the input electrical impedance of a welding system to measure the resistance of the welding system for the arc power calculation in fusion welding. This impedance can be obtained by dividing the measured voltage to current in their analytic form. Two time recorded waveforms, namely, resistance and reactance of impedance, are therefore calculated. Theoretically, the resistance used for arc power calculation is obtained by dividing measured voltage to current directly without considering the influence of inductance. Through experimental studies, we confirm that the error of arc power calculation incurred by the influence of inductance can range from 2 to 10% depending on the welding voltage and current setting. Since the proposed method can obtain the resistance of the welding system without the influence of inductance, it is a better approach as compared with the current method to obtain the accurate resistance and then arc power.

Keywords:

• Fusion welding
• Arc power
• Resistance
• Input electrical impedance

The authors wish to thank Dr B. Osamu from Jurong Shipyard Singapore for his technical assistance and Sembcorp Marine Technology Pte Ltd Singapore and Maritime and Port Authority of Singapore for providing research fund, experimental workshops and equipments.