This work is concerned with the presentation of an analytical method for the harmonic analysis of three-phase saturated reactors when used for controlling voltage in power systems. The requirements for voltage control in transmission and distribution systems through the demand for reactive power are first discussed and the various types of existing compensators which meet these requirements are presented. Particular attention is devoted to three-phase iron-cored saturated reactors. The cores of ac self saturated reactors are drive well into saturation at their operating voltages causing, naturally, non-sinusoidal currents to appear in the windings. Two possible approaches for the elimination of harmonics in the line currents are presented: use of filters and internal elimination of harmonics by means of suitable winding arrangements in three-phase saturated reactors. This work develops an analytical method for the harmonic analysis of satures reactors in which the harmonic elimination or reduction is achieved internally. The basic relations of the analytical method, which has the objective of determining the waveforms of the line and winding currents with a balanced three-phase voltage source, are then presented. The method is completely general and can be aplied to saturated reactors of any number of cores and windings. The previously described method is then applied to a particular type of saturated reactor, the Twin-tripler, and a digital computer programme is developed. The obtained results are then compared with those experimentally Known.