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KOOLMASTER PP20-VS2 rev.00
KOOLMASTER PP20-VS2
Fan Stages
6.2.
6.2.1. Principle of Operation
Operation of Fan Stages
6.2.1.1.
The controller has 12 fan stages which oper-
ate in a sequence to increase the level of ven-
tilation 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
of Fan Stages
Room
T°
Set Point
Stage x Stop T°
Stg x
Stg y
Stage y Stop T°
Stage x Start T°
Stage y Start T°
Ventilation
Level
Start temperatures of fan stages are defined
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 specific fan stage is active. Refer to
section 4.8 to enable timer-based relays.
6.2.1.2. Operation of Variable
Outputs
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.
Transition between fan stages 1 and 2
If the next stage is an on/off fan stage, vari-
able outputs are disabled at the beginning of
this on/off stage; if the next stage is another
variable-speed stage, the speed of variable
outputs is reduced the minimum speed as-
sociated with stage 2 (min speed stage 2+).
This ensures a smooth transition between
both stages. Refer to section 6.1.1 to set
the initial speed of both variable outputs for
stages 1 and 2.
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
Transition between
Stages 1 & 2
Stage 2 Stop T°
Stage 1 Start T°
Stage 2 Start T°
Speed of
variable fans
100%
Min speed
stage 2
Min speed
Off
Room T°
Bandwidth
Bandwidth
Operating Diagram of
Variable-Speed Fans
Room T°
100%
Min
Speed
Set
Point
S
tage x
S
top T°
Stage x Start T°
Stage x+1
Start T°
Fan Speed
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.
0.3°F
Summary of Contents for Koolmaster PP20-VS2
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