78
➊
➋
➌
➍
10 20 30 40 50 60 70 T/°C
%
90
70
50
30
10
2
1
0,5
➎
➏
➐
EN/06.2019/G57 © STULZ GmbH – all rights reserved
C7000 INSTRUCTIONS fOR A/C UNITS
The corresponding commands:
Opening
degree
Water temp.
Start
Gradient =
Opening degree [%]
[K]
Min.opening
Components/Cooling/Valves
G-valve/more
The setpoint for the G valve is the condensation pressure, which can be set in
the menu "Operate/Values/Refrigerant".
In this menu you can adjust the proportional factor
➊, the integral factor ➋ and
the differential factor
➌.
To avoid a drastical change you can adjust a maximum control correction
➍ per
control cycle (fixed cycle 1 second). This control correction relates to the old
actuating variable in each cycle.
In the fourth line you can enter a value for the minimal opening
➎ of the G-valve.
The minimal opening is only respected when a compressor request exists and
can be used to prevent a HP alarm.
The G valve minimum opening can be set so, that it changes in dependance on
the cooling water temperature. The warmer the cooling water, the bigger gets
the minimum opening.
This function is useful in the following case:
After the start of a compressor it may be that the adjusted condensation pres-
sure setpoint is not attained at once so that the G valve closes to its minimum
opening degree. If in this case the pressure increases rapidly, especially with
warm cooling water, the G valve, due to its mechanical inertia, can not react fast
enough to the rising pressure.
To avoid a high pressure alarm in such a case, the minimum degree of opening
can be adapted to the water temperature.
To enable this function you must set a cooling water start temperature
➏ and a
gradient
➐.
ICC
For speed controlled compressors this function should not be used, as the
risk of rapid pressure variations is low with these compressors and secondly
the compressor in case of warm cooling water may possibly not be kept insi-
de the pressure envelope (zone 1a - 1c). A compressor error would be the
consequence.
gvalve 1 pid kp 50
gvalve 1 pid ki 4
gvalve 1 pid kd 2
gvalve 1 maxc 2
gvalve 1 min 20
gvalve 1 minstart 20
gvalve 1 mingradient 1
Config
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