TAC AB, 1998-10-23 0-004-7614-0 (GB), 7:3 (24)
TAC 2413 Handbook Functional description
7.3 Air handling
7.3.1 Fan operation
The fans are controlled by the built-in time program with separate ti-
mes for half and full speed, respectively, or via manual control by
using the buttons. Full speed is disabled if the outdoor temperature is
below the set limit in P90.
The times for 1/2 speed apply to one speed operation as well.
It is also possible to control the AHU by closing an external contact
between M and X1 for 1/2 speed (one speed operation) and between
M and X2 for 1/1speed or via a pulse on input X1 or X2 which acti-
vates a built-in timer function. The timer may be set; each pressing of
the button will activate the timer from its zero position.
Forced “Off” is achieved by using manual control from the buttons or
by closing the X1 and X2 to M at the same time.
The fans are started with an adjustable and temperature controlled
time delay between them, where FF (return air fan) starts first, and
then TF (supply air fan) starts. This time delay is adjustable; it is
factory set to 5 seconds, for outdoor temperatures ≥10 °C. After
that, it will increase in proportion to decreasing outdoor temperatures.
The slope of the curve is determined by an adjustable time delay, P
33, which is factory set to 60 seconds at –10 °C, see the figure. One
or two speed fans may be controlled. For two speed fans, the switch
to full speed operation is done by closing a digital output (K3) which
is common to TF and FF. The fans are always started on half speed,
and if full speed has been chosen, the changeover to full speed will
take effect when both fans have been running for 30 seconds.
During the changeover from full speed to half speed, both fans are
stopped for ten seconds; then, FF starts, and after five more seconds,
TF starts. Full speed operation may be activated by using the time
program, manual control by using the buttons or via an external
switch. Note that if full speed is to be achieved during timed opera-
tion, both the half speed and full speed programs have to be active.
Time delay(s)
Outdoor temperature (°C)
P 33
–30 –20 –10 0 10 20 30
150
100
50
5
P 32
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