| 摘要 |
So as to permit operating a shunt-wound motor with the series characteristic without the use of electronic armature current adjusters, it is proposed to start the motor (1) with the connection of start-up resistances (R1-R4) and to control each step added by means of a comparator by a minimum armature current value (IA min o-IA min 4) specifically predetermined for each step. After said minimum value specific to each step has been reached, the comparator (7) actuates a guide and a regulating switch (Sw, Sx), whereby the minimum armature current value so reached specific to the step is kept constant by means of adjusting the excitation (I'E), and a limiting unit (17) prevents the exciting current (I'E) from dropping below a predetermined minimum value (I'E mn), which, at higher numbers of revolution (n), again leads to the shunt characteristic, now with reduced excitation (I'E min) and the resistances (R1-R4) connected specific to each step, which prevents the motor from overspeeding (FIG. 1). |
