Effect of Current on the Characteristics of Splashed Particles from AgSnO 2 Contacts in a 270 V DC Arc

Abstract Conventional studies of contact erosion rely on post-arc morphological characterization, which fails to capture the dynamic response of splashed-particle release frequency, size, and motion to current variations during material loss. To address this limitation, we developed an in situ observation system for AgSnO2 contacts under a 270 V DC air arc, integrating 650 nm pulsed-laser active illumination, narrowband filtering, and high-speed imaging. Experiments were conducted at currents of 40, 60, 90, 120, and 200 A with a fixed arcing duration of 200 ms per test. From the acquired images, we statistically analyzed the particle origin, cumulative count, diameter, velocity, and individual splashing events. Within the observable scope, all identified particles originated from the anode tip, and the cumulative particle count increased markedly with current, rising from 546 at 40 A to 1,840 at 120 A and further to 1,880 at 200 A. With increasing current, particle release occurred earlier, and multi-particle splashing events became more frequent—up to 11 particles were observed in a single event at 200 A. For the tracked particles (diameters of approximately 90, 128, and 202 μm), the velocity distributions shifted to higher values at 120 A and 200 A, suggesting a current-enhanced ejection dynamics. In contrast, particle diameter exhibited no clear monotonic trend with current, implying that size selection is not governed by the arc current alone. The above results quantitatively characterize the effects of current level on the number, frequency, size distribution, and motion state of splashed particles released from AgSnO2 contacts, thereby providing an experimental basis for further analysis of the splashing erosion process of contacts.