A method of eliminating a disturbing component from a periodic signal. The method includes the steps performing at least two measurements on the signal at two distinct instants, calculating the parameters of the disturbing component on the basis of the measurements, and subtracting the disturbing component from the signal. The invention is applicable to making an electronic capacitor voltage transformer comprising a capacitor divider constituted by a high tension capacitor and a low tension capacitor. The transformer includes a microprocessor programmed to perform the above method on the signal from the low tension capacitor.