Recent studies have proved that internal electric force of capacitors is the excitation of vibration and noise. Based on that

an equivalent current method is performed to determine the sound power of a capacitor in this paper. Before experiments

first

the electric field force of the internal capacitor in a power capacitor under the action of multi harmonic combined current is decomposed by frequency

and the electric field force component of any frequency electric field decomposed can be equivalent to an electric field force under a single frequency current. In the experiments

a set of equivalent currents is loaded on a tested capacitor unit one by one. An array of corresponding sound power of capacitor under every equivalent current is measured. The sound power levels of the stacked capacitor units are finally obtained by superimposing the sound power levels. It is found by comparison that this equivalent current method is approximately equal to that of loaded currents. The deviation is lower than 1.5 dB（ A）. In addition

the equal current test method is proposed

through reducing the amplitude of the multi harmonic combined current by equal proportion

the test can be carried out

then

the sound power of the power capacitor under the original combined current is calculated by using the formula of equal proportion sound level. The requirement for programmable multi harmonic power capacity can be reduced by this method and has good equivalence.