Power capacitor will generate numerous noise under the action of AC harmonic voltage of power capacitor. At present

the relation between the noise frequency and harmonic voltage of capacitor as well as the influence of harmonic voltage amplitude on the noise are studied and summarized both at home and abroad

but the action of harmonic voltage on the phase noise is not studied. In this paper

starting from the vibration noise excitation of capacitor

the relation between the harmonic voltage phase and the electrical filed force between the capacitor plates and the rule on the influence of the phase to the noise. The test result and the theoretical analysis is identical and it is found that for the whole odd harmonic action

when the primary phase of harmonic is 0°

the sound power of the capacitor is the maximum and

when the frequency difference is 100 Hz and the primary phase difference of harmonic is 180° the sound power of the capacitor unit is minimum.