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The time slots can be used to either start or stop the unit on condition that the remote ON/OFF digital input is
closed (ref. to unit wiring diagram). Additionally, the daily time slots of screen K2 in the “Clock” menu must be
enabled. If weekly programming is enabled, the unit must be on a day programmed for unit switch-on in screens
K6 and K7 of the “Clock” menu.
If a control system is used to monitor the unit, the unit gets started after receiving an OK signal via a serial line.
Refer to the section relating to the “Clock” menu for the programming of the time slots.
6.2.3 Switch-on through an ON/OFF digital input
The unit can either be started or stopped using a digital input on condition that it has been switched ON using
the keyboard (ref. to relevant section). The unit gets started as soon as the ON/OFF digital input is closed.
If the time slots are enabled, the unit only gets started if the current time slot is one of those enabled for unit
switch-on.
If a unit control is used to monitor the unit, the unit only gets started after receiving an OK signal via a serial
line.
6.2.4 Switch-on using the control system
The unit can either be started or stopped using the control system on condition that it has been switched ON
using the keyboard and the ON/OFF digital input is closed (ref. to relevant sections). The unit gets started as
soon as the control system changes the status of the machine status digital variable. The digital variable is
included in the list of variables in the control system.
6.3 Ventilation management
Unit start-up firstly causes the activation of the ventilation system.
After ventilation is started on the delivery side and, where provided, on the return side, the controller authorises
start-up of the other components, depending on the temperature regulation requirement.
When the unit is switched off, the fans are last to stop after the delay time set on the controller has elapsed.
6.3.1 Air flow control system
The controller allows to manage the airflow rate, both on supply and return side, if the unit is provided with
plug-fans featuring an EC brushless motor.
The unit controller commands the fans through a 0-10V analogue signal for the delivery line and a 0-10V
analogue signal for the return line, where provided. If multiple fans are fitted in the delivery and return lines,
these are controlled in parallel by one signal.
The main purpose of the air flow control system is to keep the air flow constant and as close as possible to the
stored setpoint. The air flow is calculated by the software starting from the differential air pressure, as
measured at the nozzle, using the formula below:
=
∆
where:
Q = flow rate expressed in cu.m/h;
n = number of fans;
k = typical fan nozzle constant;
∆
p = difference in Pa air pressure, as measured at the fan nozzle.
The controller uses a closed loop PID controller (inc. back action) to adjust the signal sent to the fans in such
way that the air flow rate in the system reaches and stays at the setpoint value stored.