| 摘要 |
1,025,341. Inverting. GENERAL ELECTRIC CO. Sept. 24, 1963 [Oct. 23, 1962], No. 37456/63. Heading H2F. In an inverter circuit comprising a bridge of controlled rectifiers SCR1... SR4 supplying a load 6 with pulses of current in alternate directions and in which a control signal 3 is fed to the rectifiers SCR1 and SCR2 directly and is fed to the rectifiers SCR3, SCR4 after a phase shift effected by a circuit 1 (through a transformer 2 and multivibrator 4) so that the output depends on the degree of phase shift and is zero when the phase shift is zero, an overload protection arrangement includes means for reducing the phase shift to zero on overload. The phase shifting control circuit 1 is disclosed in Fig. 3 (not shown), and comprises a phase-shifting saturable reactor 14 in series with a shaping circuit 13, normal phase-shifting being effected by a control winding 19, 21. As shown, the saturable reactor includes two parallel primary windings 15, 16 and two series connected open-circuited secondary windings, but an arrangement in which there are only primary windings is disclosed (Fig. 5 not shown). Protection is effected by short-circuiting the ports a, b, thereby eliminating the phase shifting, when overload is sensed at 7 and applied to a circuit 8. Various circuits are disclosed for effecting the short circuit; in one set (Figs. 3B, 3C, 30, 5 and 6, not shown), when the circuit 8 is a solenoid, the short circuiting depends on the operation of reed switches; in another set (Figs. 4, 8 and 9, not shown), the circuit 8 is a pulse-producing circuit, and the short circuit depends on the firing of controlled rectifiers by these pulses. The device 7 may be a resistor or a current transformer. |
