| 摘要 |
1532125 DC motor control circuits SIEMENS AG 25 March 1977 [26 March 1976] 12712/77 Heading H2J In a conveyer system having a plurality of railcars driven by respective D.C. motors and running on a rail network including at least one inclined, e.g. vertical, section and provided with current supply conductors S1, S2 for the motors, the conductors are connected to a current source N through a circuit arrangement including switching means T3 arranged to provide an electrically conductive path between conductors S1 and S2 if the voltage between the conductors exceeds the voltage of source N by more than a predetermined amount. This occurs when regenerative operation of one or more D.C. motors of descending cars (e.g. car F1) causes build-up of an excess voltage which cannot be reduced sufficiently by motors of other railcars (e.g. motor M of car F2), and when the current supply fails. A threshold circuit SS responds to the excess voltage to trigger transistor T3, which could be replaced by a thyristor. An additional turn-off circuit would then have to be provided. |
