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3 Operation
Operation
3
3.1
General overview
Figure 3-1
P set
P act
3.2
Constantly controlling and adapting the pressure in
the system
Table 3-1
No.
1.
In order to provide the consumers in the cooling water system with a consistent pressure even
under varying loads, a PI controller is used.
2.
The measured actual pressure (
compared to the set pressure (
saved in the LOGO! logic module. The PI
controller balances the difference
modifying the calculated setpoint speed.
3.
•
The difference
increasing or decreasing the motor speed
n
and therefore the flow rate
actual
•
If the motor speed
increased, more cooling water
pumped through, and the pressure
P
in the system increases.
actual
•
If the motor speed
decreased, less cooling water
pumped through, and the pressure
P
in the system decreases.
actual
∆P
4.
The difference
load (consumer flow
2 and 3.
•
When consumers are connected, the
consumer flow
P
pressure
•
When consumers are disconnected, the
consumer flow
P
pressure
Set23_RegSim
Entry ID: 23753479,
V2.3.S,
∆P
n Soll
+
PI
-
Function
P
) is
actual
P
)
setpoint
∆P
by
∆P
is balanced out by
Q
n
setpoint is
Q
is
P
n
is
setpoint
Q
is
P
is caused by the variable
Q
) of the consumers 1,
C
Q
is increased, and the
C
in the system decreases.
act
Q
is decreased, and the
C
in the system increases.
act
02/2014
distance
Comments
P setpoint
0.29bar
∆P
+
-
P actual
0.17bar
n setpoint
.
P
1054 RPM
distance
Consumers 2 and 3 active
Q P
9.0m³ /h
distance
consumers 1,2 & 3
-
Q c
Q P
+
sensor
n setpoint
1054 RPM
PI
Q P
9m³ /h
+
-
Q c
- 8.0m³ /h
sensor
+
10
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