Fan Stages; Principle Of Operation - Airstream EXPERT PN110 User Manual

EXPERT PN110
6.2.

Fan Stages

6.2.1. Principle of Operation

6.2.1.1. Operation of Fan Stages
The controller has 8 fan stages which operate
in a sequence to increase the level of ventila-
tion as the room temperature increases. Each
stage can activate two variable outputs,
on/off outputs, and a combination of timer
relays for cooling purposes. A fan stage is
activated when the room temperature reaches
its start temperature and is disabled when
the room temperature decreases to its stop
temperature.
Operating Diagram
Ventilation
Level
of Fan Stages
Stg y
Stg x
Start temperatures of fan stages are defi ned
with respect to the set point and with respect
to each other. This means that when one of
these values is adjusted, all the consecutive
values are adjusted by the same amount. For
example, if the set point is increased by 1°F,
the start temperature of all fan stages will be
increased by the same amount.
Timer-based relays in fan stages
Fan stages can activate relays that operate
following a timer (On and Off Times). This is
useful to activate misting units in timer mode
while a specifi c fan stage is active. Refer to
section 4.7.4 to enable timer-based relays.
6.2.1.2. Variable-Speed Fans
Variable outputs are activated when their as-
sociated fan stage starts (see section 4.9).
They start running at their absolute minimum
speed (see section 4.5) and their speed
gradually increases as the room temperature
increases. Variable outputs reach their full
speed when the start temperature of the fol-
lowing fan stage is reached.
Operating Diagram of
Variable-Speed Fans
Fan Speed
100%
Min
Speed
Room
T°
Speed of
variable fans 1
100%
Absolute
Min speed
Room T°
Transition between
Stages 1 & 2
V1 Bandwidth
0.3°F
Off
Transition between fan stages 1 and 2
If the next stage is an ON/OFF fan stage, the
variable output is deactivated when the new
stage starts. If the next stage is another vari-
able fan stage, the speed of the fi rst variable
stage is reduced to its minimum speed when
the second variable stage starts. This ensures
a smooth transition between both stages.
The bandwidth is the temperature interval
over which variable outputs go from their
minimum to their maximum speed. This is true
even if full speed is never reached as in the
example below: when stage 2 starts, the con-
troller decreases the speed of variable outputs
to the initial speed associated with stage 2. It
then uses the bandwidth to increase the fan
speed as the room temperature rises.
If an outdoor temperature probe is
used, it is possible the controller can
automatically adjust bandwidths 1-2 as
a function of the outdoor temperature
(see below).
V1 Bandwidth
EXPERT PN110 rev.23
Room T°
17