Device for determining the resistive torque of a rotating item of equipment, system for monitoring the operation of an electric motor and system for regulating the operating parameters of a centrifuge incorporating such a device

A system for monitoring the operation of a centrifuge comprising an asynchronous electric motor operated by a control unit delivering to said motor an alternating power-supply voltage for controlling the rotational speed of the motor,

• said control unit comprising a device for determining the resistance torque of a centrifuge rotor driven in rotation in association with the asynchronous electric motor, and said device comprising:
• means for measuring the rotational speed of the motor;
• calculating means for calculating a characteristic that represents the motor slip to produce a calculated value of said characteristic;
• comparing means, associated with said calculating means, for comparing the calculated value of said characteristic with a stored set of predetermined slip values, each corresponding to a resistive torque value and for thereby determining the resistance torque on the centrifuge rotor,
• said control unit further comprising storing means for storing a set of resistive torque values each corresponding to a type of rotor and each associated with a maximum allowable rotational speed permitted for the respective type of rotor and the centrifuge, and
• said comparing means comparing the resistive torque of the centrifuge rotor determined by said device with the resistive torque values stored in the storing means so as to determine the type of rotor and the associated allowable rotational speed, and detecting an incompatibility between the maximum allowable rotational speed and a command to drive the centrifuge rotor at a rotational speed higher than the associated maximum allowable rotational speed.

A system for controlling operating parameters of a centrifuge comprising an asynchronous electric motor operated by a control unit delivering to the motor a power-supply voltage for controlling the rotational speed of the motor so as to control rotational driving of a centrifuge rotor arranged in a chamber of the centrifuge, and regulating means for regulating operating parameters of the centrifuge,

• said control unit comprising a device for determining the resistive torque of the centrifuge rotor driven in rotation in association with the asynchronous electric motor, and said device comprising:
• means for measuring the rotational speed of the motor;
• calculating means for calculating a characteristic that represents the motor slip to produce a calculated value of said characteristic;
• comparing means, associated with said calculating means, for comparing the calculated value of said characteristic with a stored set of predetermined slip values, each corresponding to a resistive torque value, and for thereby determining the resistive torque of the centrifuge rotor,
• said control unit further comprising:
• storing means for storing a set of resistive torque values each corresponding to a type of rotor and each associated with a set of operation regulating parameters for regulating the operation of the centrifuge corresponding to the type of rotor, and
• said comparing means comparing the resistive torque of the centrifuge rotor determined by said device with the set of resistive torque values stored in the storing means so as to determine the type of rotor with which the centrifuge is equipped and delivering to the regulating means the values of the operation regulating parameters corresponding to the centrifuge rotor.