Danfoss Electronics spa
Air Handling
seq.- user manual
DKRCC.PS.RI.A1.02 / 520H4358 - Air Handling Seq. user manual - V 2.2
Produced by Danfoss Electronics spa Graphic Department, 10-2009
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12.2| Fan speed configuration
In the case of F00=REQ and F00=PID control, the fan speed configuration parameters are described in the figure
below where, for the sake of convenience, only the supply fan is indicated.
Fig 49_ [Supply and return fans - Fan speed configuration]
The percentage values corresponding to the minimum and maximum fan speeds are defined with F02 and F03;
within these values, the modulation output action is calculated as described in the figure.
The fan output is activated when the capacity requested is equal to or greater than that which can be obtained with
the fan at minimum speed.
Supply fan
The starting speed is the minimum rate if SF1=0; otherwise SF1 defines the starting breakaway time during which
the fan runs at maximum speed F03.
In SF2 it is possible to define a percentage speed you wish to avoid because it corresponds to the resonance
frequency. In this case, the fan will avoid speeds that fall between SF2-SF3 and SF2+SF3, as described in the figure.
To allow the damper to open, the supply fan is activated after a delay SF4 has elapsed after the AHU is started up.
Then is delayed of SF5 time when the unit is turned off.
Note
* To avoid that coils are working
while the fan is not running,
the coil power is limited to zero
until the fan is able to start at its
minimum speed.
Return fan
Like the supply fan, the start-up speed is minimum if RF1=0; otherwise RF1 defines the start-up breakaway time
during which the fan runs at maximum speed F03.
In RF2 it is possible to define a percentage speed you wish to avoid because it corresponds to the resonance
frequency. In this case, the fan will avoid speeds that fall between RF2-RF3 and RF2+RF3.
To allow the damper to open, the return fan is activated after a delay RF4 has elapsed after the AHU is started up.
Then is delayed of the RF5 time when the unit is turned off.
