ABB AW400 Series, Instruction Manual

Page: 38 / 72

36
5.2 Controller (AW402)
The control strategies offered by the AW400 are:
•
Standard PID Controller, with Feed Forward option
•
Average Controller
These will be discussed in detail in the following paragraphs.
5.2.1 General description
The PID Controller of the AW400 is usable in the majority of process applications. In function of the difference
between the analytic measure (Process Variable, PV), and a Set-point (SP) value, it calculates an Output
(OUT), that is applied to a final control element (f.e. dosing pump) to restore actual process value to the set-
point demand. The output is calculated with the PID algorithm, which has Proportional, Integral and Derivative
actions. The effect these terms have on the calculated output is determined by the PID configuration.
The Controller can work in Automatic or Manual mode, pushing number 0 (zero). The Manual mode let the
user modify the output manually, whereby the PID calculated output is not used. The output is driven with
push-bottoms 1 (decrease) and 2 (increase). The Automatic mode is selected pushing button 5. The set-point
is modified with the push-bottoms 6 (decrease) and 7 (increase). The output signal to drive the control
element can be either a 4-20 mA analog signal or two contacts (increase-decrease). The user can choose to
control the final element according to the characteristics of the device used. The END key consents to change
the display to that of a different function.
5.2.2 Controller’s Parameters
When the instrument is operating as a controller (AW402), the following menu become accessible:
Configuration
Output Setting
Alarms
Password
XXXXX
Menu
Operation display
Process
Calibration
Channel definition
1,2,3….
To enter
Controller Menu:
Controller
PID1
Entering the Controller Menu the accessible parameters are presented as per the following table:
1 - General Parameters (valid for all control strategies)
Description Symbol Configuration
4/20 mA / Contacts - Selection of controller output as analog 4/20 mA
signal or Contact closure (See 5.2.2.5)
Proportional Band PB Numeric entry in % (Integer positive)
Default: 100 - Range: 2% – 500%
Time Reset or Integral action TR Numeric Entry in minutes per repetition