10 Conguring the process controller
By means of the process controller, a process variable can be regulated, for instance the pres-
sure of a pump. The process controller is also referred to as "PID controller" (PID controller =
proporonal, integral and dierenal controller).
The process controller is part of a closed control loop. The variable to be inuenced (control-
led variable) is measured connuously by means of a sensor and supplied to the inverter as an
analog signal (actual value) which, in the inverter, is then compared to the reference value
(setpoint). The system deviaon resulng therefrom is supplied to the process controller
which, on this basis, decelerates or accelerates the motor speed according to the desired
dynamic performance of the control loop, so that, for instance, a pump always generates the
desired pressure.
Connecon plan (example)
The following sample connecon plan shows the control of a pump
①
. The feedback of the
variable (here: pressure) takes place via a pressure transducer
②
connected to the analog
input 1.
S5S4S3S1 S2
+
M
+
J
J
T1
T1
U
W
V
Rb1
Rb2
X105
X109
3~
Inverter
P
The digital inputs can be used to acvate funcons of the process controller. The specic
assignment of the digital inputs and type of the contacts (switches or buons, normally-closed
contacts or normally-open contacts) depends on the applicaon.
General informaon on the seng
•
The basic seng of the process controller is described in the following subchapter.
4Basic process controller sengs ^ 239
•
Oponally, the motor can be put into an energy-saving idle state if no power is required.
4Process controller idle state ^ 245
•
The rinsing
funcon which can be acvated in addion accelerates the motor in idle state
to a dened speed at regular intervals. The rinsing of a pipe system with a pump that has
been in an inacve state for a longer period is a typical applicaon. 4Process controller
rinse funcon ^ 247
Conguring the process controller
238