High speed x-ray radiography diagnostic of current interruption in circuit breakers

Abstract

High-speed x-ray radiography is used for the imaging of internal components of a low-voltage air circuit breaker during fast current interruption events. A continuous x-ray source was used to irradiate the circuit breaker during interruption, while a fast camera imaging system recorded the output visible light from the x-ray image intensifier up to a maximum rate of 4000 frames per second. Detailed time-resolved images were obtained of the movable contact position and tripping mechanism components of the circuit breaker during the interruption event. Experimental observations were used to validate numerical simulation results obtained using electromagnetics and dynamics/kinematics analysis software. In addition to imaging of the circuit breaker mechanism, molten metal streams and droplets ejected from the electrodes were also observed. Tracking of these metallic particles can provide valuable information about contact phenomena and gas flow fields in circuit breakers.