Abstract : The development of power electronics technology has led to the electronic and intelligent development of arc welding power supplies. The design, production, and maintenance of power supplies increasingly require various advanced testing methods. Simultaneously, different arc welding processes require corresponding arc welding machines with appropriate power supply external characteristics to ensure welding quality. In recent years, some microcomputer-controlled power supply detection and analysis devices have emerged both domestically and internationally. However, these devices have relatively simple functions and low levels of intelligence. In most cases, the determination of power supply electrical performance still requires manual data recording and curve description through actual welding, which is highly subjective. This paper, based on the theoretical foundation of data acquisition technology, applies the LabWindows/CVI programming language to program the Advantech PCI-1710 data acquisition card, thereby designing a system for acquiring the external characteristic voltage signals of arc welding power supplies. Keywords : External characteristics of arc welding power supply; Detection system; LabWindows/CVI 0. Introduction Arc welding technology is an important component of modern welding technology, and its application scope covers almost all welding production fields. Since the load of an arc welding power source is an electric arc, its electrical performance must adapt to the characteristics of the arc load. To ensure easy arc ignition and arc stability, the electrical performance of the arc welding power source must consider the following three aspects: 1) requirements for the external characteristics of the arc welding power source; 2) requirements for the regulating performance of the arc welding power source; and 3) requirements for the dynamic characteristics of the arc welding power source. Among these, the external characteristic shape of the arc welding power source not only affects the stability of the "power source-arc" system and welding specifications, but also relates to the arc ignition performance, droplet transfer, and operational safety. Therefore, different welding methods have different requirements for the external characteristics of the power source. To better understand the external characteristics of the arc welding power source, a data acquisition system was designed to describe the external characteristic voltage signal of the arc welding power source. This system uses the LabWindows/CVI programming language to accurately and quickly display the external characteristics of the arc welding power source visually and store the external characteristic signal of the measured power source for later data processing. [Full text download of "Voltage Signal Detection System for External Characteristics of Arc Welding Power Source Based on Virtual Instrument"]