Method for protecting rotors of centrifuges against overspeeding

摘要

The method provides for a comparison of the input desired rpm with the rotor-specific maximum rpm, which comparison is followed in the event of a positive result by a test starting in which a quotient is formed from the frequencies of the sensing pulses of the rotor and of the rotor shaft. This quotient is compared with a stored desired value of this quotient. In the event of non-correspondence, the rotor drive is immediately switched off, in the event of correspondence it is switched off by means of the overspeed protection device after a preset number of pulses have occurred. In the latter case, the rotor drive is switched on again after the absence of both sensing pulses has been detected and the overspeed protection circuit is switched over to the deactivation rpm. In the event of subsequent speeding up and at the desired rpm, the quotient of the pulse frequencies is progressively formed at short time intervals and compared with the desired value of the quotient. In the event of them not being identical, the rotor drive is switched off. This method prevents the occurrence of overspeeding either as a result of objective, functional faults or as a result of subjective control errors.