A method for processing operating data (e.g., position, setpoint, and pressure) for a valve assembly. The method is configured to associate characteristics of operation for the valve assembly with a root cause and/or a contributing factor. In one embodiment, the method can assign a first amplitude with a value that quantifies movement or jump of the valve stem that results from stick-slip on the valve assembly. The method can also assign a second amplitude with a value that quantifies a change in the data for the setpoint. The method can further ascertain the relationship or position of the first amplitude relative to the second amplitude, or vice versa. The method can use the relationship between the first amplitude and the second amplitude to indicate the root cause of the operation of the valve assembly.

Disclosed is a method in which the propulsive power of a drive nozzle (2) is controlled by means of a programmable logic control device (24) having an adjustable internal controller (25) in dependence upon the rotational frequency of a turbocharger rotor (1) detected by a speed sensor (26). Parameters necessary for control are determined empirically in a tuning run which includes tuning the controller (25) to a proportional control action with high gain Kp and inputting the nominal balancing speed as target value for the controller (25), monitoring and comparing the actual speed with the target value. If the actual speed exceeds the set target value, halving the gain Kp of the controller (25) and repeating the run until the actual speed is below the set target value. Then it includes approximating the actual speed to the target speed by generating an additional target value, additively applying the additional target value to the target value, and incrementing or decrementing the additional target value until the target speed of the turbocharger rotor (1) is reached.