Gate Windings in Series

Figure 7-10 shows a saturable reactor with its gate windings connected in series with each other. The 2-core saturable reactor and its equivalent are capable of two modes of operation when the gate windings are connected in

Figure 7-10. (a) Saturable reactor with gate windings in series; (b) load current; (c) control current for noninductive load

series. In one of these, the impedance of the control circuit is low enough to permit free even-harmonics to circulate in that circuit. In the other mode of operation, the free even-harmonics are suppressed in the control circuit by connecting a high impedance, usually a choke, in series with the control windings or by providing leakage flux paths of small reluctance in the cores.

When the even-harmonics are allowed to circulate freely in the control circuit, the wave form of the output current is the same as that of the parallel-connected gate windings, whereas suppression of the even-harmonics in the control circuit produces an output current with a rectangular wave form if the magnetization curve is as assumed in Fig. 7-9(a) with the gate windings connected in series.