Welding machines are among the major energy consumers in industrial fields. Their energy efficiency has received significant attention in recent years and has been incorporated into the scope of energy efficiency labeling management. This paper briefly introduces the current status of energy efficiency in welding machines

summarizes and analyzes factors affecting their energy efficiency identified during testing processes

and proposes targeted improvement strategies. Additionally

comparative tests were conducted on three-phase/single-phase and inverter/mains frequency welding machines under four power supply conditions—grid voltage

induction voltage regulation

frequency converter

and purified power supply—to investigate the impact of power supply quality on measurement results of efficiency (η) and power factor (pf). Research indicates that optimizing installation structures

adjusting circuit parameters

and improving manufacturing processes can effectively reduce internal losses in equipment

enabling arc welding machines to achieve higher energy efficiency ratings. The harmonic distortion level of the power supply significantly affects energy efficiency test results for the same welding machine

necessitating strict adherence to relevant standards regarding power supply quality requirements during efficiency testing. This study provides reference value for enhancing energy efficiency and conducting energy efficiency evaluations of arc welding machines.