BA-40400-02-V14 | 25
Operating instructions
ATTENTION!
If during ongoing operation, due to faults or the like,
the end position and/or the zero point is not reached
after approx. 10 minutes, the “Servo motor alarm”
error message will be displayed. The error tolerance
is coupled to the switching hysteresis of the “3-point
step” control type. .
A servo actuator without feedback can also be operated. This is to be
selected with the configuration.
If no positional feedback is available, measure and adjust the motor life
(see chapter “12.1.13 Menu 5: Service” on page 34).
ATTENTION!
Entering a wrong motor life may prevent accurate
controller functioning. In this case you would receive
no warranty coverage by the manufacturer. The mo-
tor cycle time is set by the factory at 120 seconds
which corresponds to the cycle time of the motor of
the chlorine gas valve C7700.
7.2.6 Continuous control output (20 mA current output)
For automatic controllers a continuous control output of 0/4 … 20 mA
can be configured for the control of continuous actuators.
The current varies between 0 and 20 mA depending on the deviation.
Max. load: 500 Ohm
The 20 mA current output for free chlorine is switched on for every
configuration.
You can choose between:
• 0...20 mA
• 4...20 mA
• 20…0 mA and
• 20...4 mA
7.3 Output restriction
The maximum output of each controller can be restricted. To do this,
enter the maximum percentage value the actuator can reach.
Example: If a value of "80%" is entered, the controller moves the ac-
tuator up to a maximum of 80%. The control algorithm however is still
calculated to "100%". Note that the controller parameters are selected
accordingly.
The lowest maximum setting is "50 %".
This limit is useful if for example an oversized dosing pump has been
fitted. This will ensure precise control.
7.4 Actuator
Components such as pumps and solenoid valves, which are controlled
by the TOPAX, are called actuators.
Depending on the final control element used, different control functions
can be set. Possible options are a continuous output with impressed
current (0/4 … 20 mA), or control outputs (with pulse frequency). The
latter can be controlled as electronic (optocoupler) or relay outputs.
8 Controller explanation
8.1 Definitions
Term
Definition
actual value (X)
The actual value of X of the measurement for the
respective sensor is constantly indicated.
Setpoint (W)
Setpoint W of a control system defines the level at which
the controller should settle the process and keep it
constant.
Control deviation
(X-W)
Control deviation X-W occurs if the actual value X of
the measurand differs from setpoint W. Control variable
Y results from the control deviation and the control
parameters set.
Control vari-
able Y
Control variable Y of a control system defines the
value which the controller transmits to the final control
element depending on the parameters set and control
deviation X-W (between 0 % and 100 %).
8.2 Proportional controller (P controller)
8.2.1 Proportional range Xp
(proportional effect or amplification of the controller)
The proportional range Xp (p-range) of a proportional controller indicates
the amount by which the measurand X must deviate from the setpoint
W, so that the control variable Y = 100%. If the control deviation is less,
the control variable is reduced proportionally.
Control variable Y of a P-controller is affected proportionally only by the
control deviation (X - W).
The P-range is indicated in "%" and always refers to the measuring
range final value.
The proportional range is therefore an indirect measurement of the con-
trol amplification K
R
:
K
R
= 100% / Xp%
For an Xp range of 50% the control amplification is accordingly:
100 /50 = 2 -> controller amplification K
R
= 2
Xp = 50% means that the control variable Y changes 100% if the actual
value deviates by 50% from the setpoint (related to the measuring range
final value).
8.3 Proportional-integral-derivative controller (PI, PID
controller)
8.3.1 Reset time Tn
(integral effect of PI controller)
The integral time of a PI or PID controller is called the reset time Tn.
The integral time is the time required by the control variable Y with a
constant nominal/actual deviation to achieve the same change in output
signal as produced immediately by the P proportion immediately after
the change in the nominal/actual deviation.
