118
Stability problems
The speed control contains a „PID controller“. It ensures an exact and fast adjustment of the
actual value to the set value.
In applications such as solar systems and charging pumps,
the factory settings likely regulate in a stable manner.
Especially the DHW preparation via
external heat exchangers (fresh water station) adjusting these values to the specific circum
-
stances is absolutely necessary. In this case, the additional use of an ultra-fast sensor (op
-
tional accessory MSP60 or MSP 130) at the warm water output is required.
The
proportional component
represents the reinforcement of the deviation between the de
-
sired and the actual value. The speed is changed by one increment for each
x * 0.1K
of de
-
viation from the desired value. A large number leads to a more stable system but also to
more deviation from the predefined temperature. In the example, is set to 5. This means that
the speed is adjusted by one level for every 0.5K of deviation from the set value.
(FS = 5)
If the
actual value
and the
set value
are identical, the output variable is the
median
between
minumum and maximum variable.
Example:
minimum variable
30,
maximum variable
100,
set value = actual value
à
variable
=
65
The
integral component
periodically adjusts the speed relative to the deviation remaining
from the proportional part. For each 1K of deviation from the desired value, the speed chang
-
es one increment every
x
seconds. A large number provides a more stable system, but it
takes longer to reach desired values. With an integral component of e.g. 5, the speed is
changed per 1K of deviation from the set value every
5
seconds by one level. (FS = 0)
The
differential part
leads to a short „overreaction“ the faster a deviation between the de
-
sired and the current value occurs, to provide a fast compensation. If the desired value de
-
viates at a rate of
x * 0.1 K per second
ab, the speed is changed by
one
level. High settings
provide a more stable system, but it takes longer to reach desired values. If the differential
part is set to e.g. 5, the speed is changed by one level if the set value deviates at a rate of
0.5K
per second. (FS = 0)
In some cases, the parameters for
proportional, integral
and
differential component
must
be assessed by trial and error.
A typical result of the
DHW preparation
(fresh water station) with fast sensors is Prop. = 3.0,
Integr. = 3.0, Diffr. = 1.0 for pump with PWM signal. In practical experience, the settings
Prop. = 3.0, Integr. = 1.0, Diffr. = 4.0 have proven useful combined with usage of an especial
-
ly fast sensor.
Summary of Contents for UVR65
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