| 摘要 |
1,147,848. Automatic current control. LICENTIA PATENT-VERWALTUNGS G. m. b. H. Jan. 19, 1968 [Jan.31, 1967], No.3014/68. Heading G3X. [Also in Division H2] A constant-current circuit of a driving installation comprising D.C. motors 10, 11, is supplied from series-connected rectifiers 12, 13, connected to a constant voltage network 14 through a choke coil and a capacitor respectively, the reactances of the coil and the capacitor being substantially equal at the network frequency. The coil 17 may be tapped and the capacitor may comprise two components 18, 19, so that actuation of a change-over switch 20 enables the motor current to be adjusted to two values. Retardation resistors 21, 22, absorb reverse power when the motors operate as generators, these resistors being normally shortcircuited by switches 23, 24, under motoring conditions. The switches 23, 24, are opened only when a predetermined value of current is exceeded, and are closed when regeneration ceases. For providing a dropping speed-torque characteristic, the resistors 21, 22, may be connected continuously or intermittently in parallel with the motor armatures by means of the switches 25, 26, in which case the switches 23, 24, are closed. A falling speed-torque characteristic may also be obtained with the aid of shunt field windings 29, 30, associated with Zener diodes 31, 32, acting as non-linear resistors. |
