Abstract: A saturated reactor adapted for direct connection to an EHV line and thus constituting a combined reactor and transformer. A problem arises in that earthing of the primary winding star point would normally short circuit the 3rd harmonic. The invention overcomes this by series connection of primary coils coupled to three limbs whose fluxes are spaced at 40.degree.. 3rd harmonic voltages therefore cancel in the series primary windings. The series primary windings may be obtained as separate coils on individual limbs or as one coil (per phase) embracing three limbs. Elimination of the 3rd harmonic enables the ninth harmonic to be short circuited in a mesh winding.

Abstract: A saturated reactor of the type, for example the treble-tripler reactor, in which groups of 3-phase windings are connected in series to produce multiple flux phases in respective core limbs to achieve harmonic compensation. The windings are connected between the line terminals and a star-point which cannot normally be earthed if large 3rd harmonic components are to be avoided. In this invention the zero-sequence impedance of the reactor is kept at a low value by duplicating the complete primary winding and connecting the two duplicates in zig-zag star. The resulting star point can then be earthed without upsetting the harmonic compensation of the reactor.

Abstract: An alternating current power transmission system employing a long transmission line has a stabilizing arrangement comprising a plurality of alternating current saturated reactors connected to intermediate stations along its length, at least some of the reactors having slope correction capacitors in series therewith, and others of the reactors having slope reactances which are not connected by series slope correction capacitors. Since the uncompensated reactors have a substantially instantaneous transient response the stabilizing arrangement gives an overall voltage control which is better than one incorporating only slope corrected reactors.