Sartorius DCU 3 - Main Function: Control Loops; Control Loops Equipment and Principles

Operators Handbook DCU3 – System
6., Main function „Control Loops“
BAEDCU3 - Rev. 4.6 - 0504 6 - 1
6 MAIN FUNCTION „CONTROL LOOPS“
6.1 Equipment and Functional Principles
All control loops in the DCU3 - system are DDC controllers. They operate either as PID controllers,
setpoint controllers or on/off controllers and are adapted to the related control loops. Depending on the
actuator their output is either continuous or pulsewidth-modulated (pwm). Both single- and split-range
controls are possible. The controller structure (PID) can be parametrized, if necessary. Switching over
between the operating modes is carried out with bumpless transfer.
 These modes can be selected:
Mode State of controller
off controller switched off with defined output
auto controller in operation
manual manual control of controller / actuator
profile time profile for setpoint
cascade servo controller in cascade control loop
In the controller display you can enter actual values, operating modes and controller outputs. Effective
ranges depend on the configuration implemented for a specific fermentor. The parametrization display
for adjustment of PID parameters, output limits and deadband is accessible via a password. In remote
operation setpoint and operating mode are specified by the host computer.
 The extent of implemented controllers depend on the fermentor system and/or the individual
customized configuration. The controllers shown below can be implemented at present.
Temperature controller PID cascade controller, pwm-splitrange outputs for heating /
cooling
Stirrer controller Setpoint controller for external motor control
pH controller PID controller with pwm-split-range outputs for acid/base
pO
2
controller PID cascade controller for speed, airflow or pressure servo
controller (switchable)
pO
2
gasflow ratio controller Master controller for gasflow ratio controller
Gasflow ratio controller Ratio controller of two external massflow controllers
pO
2
Gasmix controller PID controller, with pwm continuous outputs for control of
N
2
/O
2
Airflow controller Setpoint controller for external massflow controller
Foam controller On/off controller for antifoam
Level controller On/off controller external harvest and/or feed pump
Feedpump controller Setpoint controller for external dosing pump
Pressure controller PID controller, continuous output pressure control valve
Weight controller PID controller, pwm-output for external harvest pump
Dosing controller PID controller for control of a external dosing pump
Note: Additional or alternate controller functions can be implemented into existing DCU-systems
lateron by changing the configuration, for instance. Above this, the software allows imple-
menting of special control functions, if necessary.