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Control and Protection Functions
Heating cable switching
In cases where a heating cable is used as a frost protection for
condensate drain siphons, the control unit ensures its switching
according to the outside temperature. The preset switching
temperature is 2 ° C (hysteresis 1 K), the power according to the
cable used is self-regulated.
Temperature Required Value Compensation
Temperature compensation is actually a correction (shift) of the
required value (set point) of the controlled (room) temperature
according to the outdoor temperature sensor reading, which
adjusts (in addition to other correction values) the temperature
specified in the temperature mode settings. It is mainly used to
reduce differences between outdoor and indoor temperatures
(to eliminate thermal shocks) and the energy demand of device
operation. On the other hand, it can increase differences ("ag-
gressiveness") in control, if adjusted reversely.
Note: The data point values on the controller are described in
full text (not using abbreviations like TH1, TC1, etc.). Generally,
minus control is also possible.
Figure 11 – Actual set-points with compensation (shift)
Control signal for controller
heating
H shift
TH1 ......Basic set-point of the required temperature for heating – upper heating limit
TH2 ......Actual/current set-point of the required temperature for heating – upper heating limit = (TH1 - shift H)
TC1 ......Basic set–point of the required temperature for heating – upper cooling limit
TC2 ......Actual/current set-point of the required temperature for heating – upper cooling limit = (TH1 -shift C)
H shift
for heating set-points (A negative shift causes a reduction in the required temperature for heating.)
C shift
for cooling set-points (A negative shift causes a reduction in the required temperature for cooling.)
Figure 12 – Fan Speed Compensation Description
delta speed (%)
Heating Compensation Settings
(Winter)
T3 .....Starting point for heating compensation
T4 .....End point for heating compensation
c ........Max. compensation value (delta T)
x.........Actual outdoor temperature
y.........Actual fan speed shift for heating
Figure 13 – Set-Point Compensation (Shift)
delta T (K)
Heating compensation settings
T3 .....Starting point for heating compensation
T4 .....End point for heating compensation
c ........Max. compensation value (delta T)
x.........Actual outdoor temperature
y.........Required heating set-point shift
16
cooling
Room set-point
C shift
Cooling compensation settings
(summer)
Outdoor temperature (°C)
T1 .....Starting point for cooling compensation
T2 .....End point for cooling compensation
C ........Compensation value (delta T)
X ........Actual outdoor temperature
Y ........Actual fan speed shift for cooling
Cooling compensation settings
Outdoor temperature (°C)
T1 .....Starting point for cooling compensation
T2 .....End point for cooling compensation
C ........Max. compensation value (delta T)
X ........Actual outdoor temperature
Y ........Required cooling set-point shift
Fan Speed Compensation
The VCS control unit system enables the pre-set fan speed to be
adjusted depending on the air temperature, air quality or mixing
damper position using fan speed compensations. The sum of
individual compensations creates a so-called total compensation
which affects the fan speed change.
Outdoor Temperature-Dependent Fan Speed
Compensation
The compensation adjusts the fan speed in regards to high or
low outdoor temperatures. The fan speed is adjusted depending
on the maximum heating or cooling compensation settings. A
positive compensation value represents a fan speed increase. A
negative compensation value represents a fan speed reduction.
Note: To make the compensation effective, it is necessary to
set a suitable maximum compensation value if only one com-
pensation is used.
Room (Outlet) Temperature-Dependent Fan Speed Com-
pensation
The fan output is adjusted depending on the required room
temperature and the measured room (supply air) temperature.
The compensation will be activated if the measured temperature
is lower than the required temperature.
Using the compensation function, the fan speed can either be
increased or reduced.
Heating/Cooling-Dependent Fan Speed Compensation
The request for heating or cooling is evaluated by measuring the
supply air temperature and comparing it with the required supply
air temperature and then followed by fan output compensation.
The compensation will be activated if the difference between
the required supply air temperature and the actual supply air
temperature is greater than the pre-set temperature hysteresis.
The actual correction extent is related to the settings of the PID
controller constants.
n
Heating Compensation: It reduces the fan output and thus
sufficient supply air heating is achieved based on the smaller
air volume (used to eliminate insufficient output of the heat
exchanger).
n
Cooling Compensation: It increases the fan output (higher
air-flow rate) and thus makes the room environment more
comfortable, if cooling is insufficient.
This type of compensation also enables a change to the priority
cooling – fan. So the change in the fan speed is applied first
and then active cooling is applied as the request for cooling is
rising. The settings can be performed using the HMI controller,
refer to the chapter Additional Operating Mode and Function
Setting Options.
Air Quality-Dependent Fan Speed Compensation
The fan output can be adjusted depending on the measured CO
(VOC, CO) content and the pre-set required value. If the CO
CO) content is higher than the pre-set (permissible) value, the fan
speed will be increased. The compensation extent is affected by
the settings of the PID controller constants. The measured value
range must be set depending on the sensor used. Further, the
sensor characteristic (Normal ascending for CO
Inverse descending for CO) must be set. For the settings, refer
to the Data Points.
2
(VOC,
2
and VOC or
2
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