Order No. 2104 ..
If the "Type of heating" or "Type of cooling" parameters are set to "Via control parameters" it will
be possible to adjust the control parameter manually. The feedback control may be
considerably influenced by presetting the proportional range for heating or for cooling (P
component) and the reset time for heating or for cooling (I component).
i
Even small adjustments of the control parameters will lead to noticeable different control
behaviour.
i
The adaptation should start with the control parameter setting for the corresponding
heating or cooling system according to the fixed values mentioned in tables 2 and 3.
Figure 24: Function of the command value of a PI control
y: Command value
x
d
: Control difference (x
d
= x
set
- x
act
)
P = 1/K : Configurable proportional band
K = 1/P : Gain factor
T
N
: Configurable reset time
PI control algorithm: Command value y = K x
d
[1 + (t / T
N
)]
Deactivation of the reset time (setting = "0") ->
P control algorithm: Command value y = K x
d
Parameter
setting
Effect
P: Small
proportional range
Large overshoot in case of setpoint changes (possibly permanently),
quick adjustment to the setpoint
P: Large
proportional range
no (or small) overshooting but slow adjustment
T
N
: Short reset time Fast compensation of control deviations (ambient conditions), risk of
permanent oscillations
T
N
: Long reset time Slow compensation of control deviations
Table 4: Effects of the settings for the control parameters
Page 76 of 171
Software "KNX CO2 sensor"
Functional description
