The selection of capacitor capacity cannot exceed a few percent of transformer capacity.

Without this standard, 20-40% of the transformer capacity is generally used, and the compensation amount exceeds 50% under special circumstances. Moreover, sometimes the installed capacity is far more than 50%, which is related to the capacitor's output at low voltage and high rated voltage. Assuming that the rated voltage Uc of the capacitor is Qc and the voltage applied to the capacitor is U0, the operating output of the capacitor when the voltage U0 is applied is Q0=Qc*U0*U0/Uc/Uc, and U0 must be less than Uc.