The metal particles generated in the Gas insulated metal-enclosed switchgear (GIS) is mainly the micron to sub-millimeter metal chips of such metal parts as screws and contacts due to friction and

in addition to the electric filed during the operation of the equipment

is also subjected to the sinusoidal steady excitation. To this end

the AC voltage superimposed with sinusoidal vibration excitation test platform is set up

and the initial motion and discharge characteristics of sub-millimeter metal particles of different particle sizes under the action of AC voltage alone and AC voltage superimposed with sinusoidal vibration excitation are compared and studied. The study results show that the motion of sub-millimeter metal particles at initial stage is divided into such two stages as the initial jump and the stable jump. The initial jump is characterized by the small and rapid motion of individual particle

and the jump process before entering the stable jump stage is divided into such four stages as the initial jump

the rejump

the collision-driven and the self-sustained jump. The effect of sub-millimeter metal particle size on the initial characteristics is significant

and the initial jump voltage

stable jump voltage and quenching voltage decrease and then increase with the decrease of the particle size. Compared with the condition of AC voltage

the initial jump voltage

stabilized tripping voltage and quenching voltage are decreased to some extent after the superimposed sinusoidal vibration excitation. The discharge characteristics at the initial stage are studied by the pulse current method and ultrasonic method

and the results show that sinusoidal vibration excitation can significantly reduce the PDIV

which in turn weakens the partial discharge intensity at the initial stage.