Method for protecting centrifugal separators against overspeeding

摘要

Method for protecting against overspeeding centrifugal separators which are preferably driven with a three-phase synchronous motor with a memory-programmed frequency convertor control. The time base, which is prescribed by a quartz-stabilized circuit, for frequency formation is tested even at low starting frequencies by a computer algorithm during the starting routine by counting out the oscillations of a second independently operating quartz oscillator at a higher frequency. The second testing in the scope of the computer routine is carried out by means of a constant comparison of the frequency set value with the upper value of the working range, both values being stored in a working memory. The third monitoring takes place at the absolutely acceptable limit frequency which is stored in a read-only memory and compared with the frequency set value. When a higher frequency is detected in any monitoring step, the frequency set value is forcibly adjusted automatically by the computer routine to a value which is equal to or smaller than the limit frequency value.