Abstract: A device for stabilizing the voltage between two conductors of an a-c network comprises a thyristor switching circuit and a choke element connected in series between the conductors and in parallel to a control circuit. The control circuit activates the thyristor circuit to connect the two conductors upon detecting equality between a predetermined reference value and a sum of two areas under a half-wave portion of the voltage-time curve of the two conductors, the first area being measured by an integrator and extending from the beginning of the half-wave period to a current instant and the second area being calculated by analog arithmetic components and extending from the current instant to the end of the half-wave period.