Why does the low-voltage parallel self-healing capacitor make a buzzing sound when it is just running?

During the initial operation stage, the low-voltage parallel self-healing capacitor emits a "buzzing" sound, which is a common abnormal phenomenon in power system operation. This sound could either be a normal indication of vibration or could be a sign of potential faults. So, what causes the buzzing sound when the low-voltage parallel self-healing capacitor is just operating?

Ⅰ. Normal vibration phenomenon

Medium activation: The initial polarization process of the internal medium of the new capacitor
Stress release: The physical adjustment of metal components due to thermal expansion and contraction
Electromagnetic vibration: Minor oscillation of the plates caused by the alternating electric field
Process residue: Gradual expulsion of gases during the manufacturing process

II. Electrical Abnormal Factors

Partial discharge: A micro-discharge phenomenon occurring at the weak point of insulation.
Harmonic resonance: Mechanical resonance triggered by specific frequency harmonics
Poor contact: Intermittent arcs caused by loose connection terminals
Self-healing reaction: The energy release when defect points in the medium self-heal

III. Mechanical Structure Issues

Fixation loosening: The support frame was not fully tightened during installation.
Internal displacement: Minor misalignment of components caused by transportation vibrations
Shell deformation: Stress changes in the shell caused by temperature variations
Foreign substances entering: Residual substances from production or impurities introduced during installation

IV. Environmental Impact Factors

Temperature shock: Material deformation caused by rapid heating
High humidity: Surface discharge caused by condensation
Contamination deposition: Local surface discharge caused by conductive dust
Electromagnetic interference: Strong alternating magnetic fields generated by adjacent devices