Airstream TC5-ITA User Manual page 16

TC5-ITA
Opening of the Air Inlet During Variable Stages
A step is also added when a variable stage starts increasing in speed, right
after the stage's differential. This step is called " Step x Hi ". The step
number is not increased as we are dealing with the same ventilation stage.
In the previous graph, Step 1 corresponds to the activation of Stage 1 and
Step 1 Hi signals the point where Stage 1 fans reach their full speed.
The user must thus define the inlet opening position (in time or %) required
at the beginning and at the end of each variable stage. Once this is done,
the user can choose to subdivide this opening time or % into 0 to 2 inter-
mediate opening steps to progressively open the inlet during the variable
stage.
When intermediate opening steps are enabled, the controller splits up the
variable stage's opening time or % evenly between the number of interme-
diate steps (e.g., if one intermediate step is enabled, the controller will
open the inlet two times during the variable stage (open 50% of the vari-
able stage's opening time (or %) at the first intermediary step, 50 % at the
end of the variable stage).
Intermediate steps are activated when the variable stage reaches pre-
defined fan speeds. These fan speeds are set differently depending on the
number of intermediate steps in use. For example, if 1 intermediate step is
enabled, the inlet opens during half the variable stage's opening when the
stage's speed is of 75 %;
it reaches the stage's HI
opening position when the
fan speed is 100 %.
The three following graphs
illustrate when each inter-
mediate step starts.
16
TC5-ITA rev.02
During a Variable Stage
with 0 Intermediate Step
Opening
(Time or %)
Step HI
Opening
Step
Opening
50 %
Opening of the Inlet
100 %
Variable
Stage
Speed