Abstract: In a centrifugal separator of the type in which driving power of a motor is transmitted to a rotor via a power transmission mechanism, such as a belt, a motor-rotation signal frequency fm and a rotor-rotation signal frequency fr are computed, on the basis of which a frequency ratio A (fr/fm) is computed. When the frequency ratio A exceeds the upper limit of a first predetermined range, a warning message is displayed to prompt the user to perform maintenance. When the frequency ratio A exceeds the upper limit of a second predetermined range, an alarm message is displayed and the motor is stopped.

Abstract: A laboratory centrifuge, whose centrifuge rotor is mounted in a bowl (6) which can be brought to the correct temperature and which is set up in particular for the setting of temperatures below the ambient temperature, is provided with a drive means comprising at least one electric motor (1) which is equipped with standstill heating means to maintain the temperature within the motor above a dew point temperature independent of a material-specific cooling temperature within the bowl (6). The standstill heating is provided by the winding system of the stator and/or of the rotor of the electric motor (1) and is connected to a control device (21). The formation of condensation within the motor and the consequential adverse effects arising from this, such as for example corrosion damage to electrical contacts as well as to the bearings of the motor shaft, can be avoided by this means. Also, no additional components are needed for the actual standstill heating.

Abstract: A centrifugal apparatus is disclosed which includes a rotor, a motor, a speed signal generator, including a disc having alternate reflective and non-reflective stripes, for generating a rotating speed signal of the rotor, a microprocessor (mpu), an analog processing circuit. The rotating speed of the rotor is judged by both the microprocessor and the analog processing circuit including a F/V converter and a voltage comparator independently, so that an overspeed condition is prevented. The mpu may further detect a motor rotating speed and compare the variation in the rotating speed signal of the rotor and the rotating speed of the motor. If the difference exceeds a reference, the mpu stops the rotor. Another disc of which reflective strip is replaced by a non reflective strip may be provided to the rotor and a pulse compensation circuit for compensating the lack of the pulse in the rotating speed signal is also provided. This type of the disc is provided to distinguish the types of these rotors.

Abstract: A centrifuge rotor overspeed protection system which can operate with rotors of at least two speed ranges. A set of coding elements are provided on the rotors coded to represent the actual maximum safe speed rating of the rotor. An additional set of coding elements coded to correspond to the maximum speed in the lower speed range are also provided such that the rotor can be operated at the maximum speed possible in a prior art centrifuge designed for operation in the lower speed range. The detection circuit for the coding elements automatically adjusts the detection threshold depending on the average values of the sensor output peaks corresponding to the codes.