User manual - CONTROLLER PUR-94
Figure 6.4. Process of peaks detection
6.2.
PID
REGULATORS
Operation of the PID controller involves calculating the error value ensuing from the
difference between the setpoint and the measured value and responding in such a way as to
minimize the calculated error by appropriately adjusting the signal connected to the input of
the regulated object.
Controllers are mainly used in industrial control systems that have large time constants
vulnerable to interference from the input of the regulated object, and therefore are suitable for
constant value regulating of the object or technological processes that contain such elements
as furnaces, boilers, etc.
The
device includes a proportional-integral-derivative (
PID
) controller with two
independent control loops, one for controlling the heating process and the second for the
cooling system (a general diagram of the controller is shown in
). Hereafter these
loops are called
PID H
loop and
PID C
loop respectively, as shown in
. Each of
these loops is composed of the following blocks:
P
proportional,
I
integral and
D
derivative,
whose proper summing up gives the output signal controlling the object
The controller’s signal may be redirected to any output of the device, which means that
may be used to control most objects used in the industry.
The PID controller can be used to adjust such values as temperature, humidity, pressure,
force, speed, flow rate, or level of a liquid or loose material etc. Note, however, that the
controllers included in the device have a common setpoint (
SEtP
parameter), and so should
be used in applications where one of the controllers (e.g.
PID H
) is used to control actuators
that increase the state of the regulated object (e.g. heating), and the other controller (e.g.
PID
C
) is used to control actuators reducing the state of the regulated object (e.g. cooling).
Additional controller parameters such as: dead zone, fuzzy logic block or inertial block,
enables even more precise control over the physical object, optimizing, but also protecting the
object against over-regulation or an excessive rise of the control value.
22
”timE”
measure
time
”timE”
”PEA”
”PEA”
real measurement result
display value
