Analysis of short-circuit failure paths and causes of high-reliability tungsten-copper electrode gas discharge tubes

• Published in: Engineering failure analysis 2025-02, Vol.168, p.109092, Article 109092
• Main Authors: Cao, Hefei, Xin, Tongze, Han, Congying, Cai, Pengcheng, Zhang, Guohua, Wang, Min
• Format: Article
• Language: English
• Subjects: Discharge testing; Gas discharge tube; Short circuit failure; State characterization; Tungsten-copper electrode
• ISSN: 1350-6307
• DOI: 10.1016/j.engfailanal.2024.109092

•Using X-ray analysis and CT scanning analysis to observe the failure path of gas discharge tubes.•Non-destructive disassembly of highly reliable gas discharge tubes and observation of structure through various characterization methods.•Analyze the short-circuit law of gas discharge tubes by comparing the differences in insulation resistance levels. In engineering practice, it has been found that as the number of surge discharges increases, gas discharge tubes exhibit short-circuit failure, significantly affecting the normal operation of the protected system. This study obtained gas discharge tubes failure short-circuit samples at a current of (235–240 A) through a self-built discharge testing platform. By combining multiple characterization methods and based on the classification of failed insulation resistance, it was determined that the main short-circuit failure paths are conductive tube walls and conductive electrodes, both caused by stacked or free electrode matrix particles. Through non-destructive disassembly, it was found that the failed samples exhibited significant differences compared to new samples. Specifically, the anode electrode and tube wall showed material stacking and growth, while the cathode electrode exhibited degradation and erosion, with the severity increasing as the insulation resistance progressively decreased. After the completion of cathode electron powder splashing, the tungsten copper electrode accelerates dissociation under the dual effects of maintaining arc discharge and melting splashing. Droplets splash onto the side of the anode or tube wall, solidify, and adhere, gradually accumulating to form surface particles. Some molten droplets bounce back when they come into contact with the electrode or wall, solidify into free tiny particles. These free particles accumulate in the grooves of the tube wall under the influence of gravity or energy waves. When a circuit is formed inside the gas discharge tube by these tungsten-copper particles, the gas discharge tube short-circuits and fails.