摘要 |
Described and claimed is a method, in which the state of a mill, which consists of a stator and a rotor and is driven by an alternating current motor, is derived from the rotational speed of the mill work. The rotational speed is measured with the aid of a rotating component connected to the mill work in a torque-proof way, especially with a Hall sensor, which co-operates with a permanent magnet fastened to said component. The determined speeds—normal for a normal operation of the mill and zero or very low in the event a blockage of the mill work—are put in relation to the idling rotational speed, which is also determined and is put in relation to the mains frequency. The determined rotational speeds are stored, and can be displayed. When there is a blockage, an alarm can be sounded.
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