CORRIGO VENTILATION 3.6 MANU

36 Chapter 5 Functional description Manual Corrigo Ventilation, revision V
5.1.4 Types of chillers
Step controller Heating / DX cooling
As alternative or complement to the above mentioned analogue control, heating and cooling can be
activated in steps. The internal signal is then used to activate digital outputs for control of the
heaters/chillers. Up to four heater outputs and three cooler outputs can be configured. There are two
possible modes:
Sequential control
Each output step has individually settable on and off values in percent of the control signal. The
number of steps is equal to the number of heater/chiller groups. Minimum on and off times can be
set, i.e. the minimum time the step has to be inactive or active for a change to occur.
Binary control
The heater power outputs should be binary weighted (1:2:4:8 for heating, 1:2:4 for cooling). The
number of loads to be controlled is set. Thereafter the program will automatically calculate the
individual activation levels. Switching differential and minimum on/off times can be set. The number
of heating steps will be: 2
no. of groups
-1. In binary mode, the analogue output signal may be used to fill
out between the steps. The signal will go 0…100 % between the activation of each step. The load
connected to the analogue signal should have the same size as the smallest of the binary groups. In
the example below there are 4 heater groups (1:1:2:4) and the total number of heating steps is eight.
Step controllers and Change-over
The digital output signals "Heating/cooling step 1", "Heating/cooling step 2" and "Heating/cooling
step 3" are used for step controllers during change-over control (see section 5.1.12). They have the
same functions as other step controller outputs, but are set to either heating or cooling depending on
whether heating or cooling is required.
DX cooling with room or extract air control
If DX cooling is used in conjunction with room temperature control or extract air temperature control,
there are two configuration alternatives, DX cooling or DX cooling with exchanger control.
DX cooling without exchanger control
When running cascade control, the supply air controller setpoint is normally controlled by the
room/extract air controller output signal.
When DX cooling is activated, the supply air controller setpoint is lowered to five degrees (adjustable)
below the setpoint given by the room/extract air controller. This prevents the DX cooling from being
activated/deactivated too often.
1
1
1
1
2
4
2
Y1 = 1