The solar plant switches on as soon as the temperature in the panel (main
controlled variable) is 5 K above the storage tank temperature (differential
controlled variable):
Example of solar plant
(differential variable)
DO
AI
T
T
Y
X1
Y
SI
G
N
AL
Y
LABEL
TEMP
y p y p
y p
x
x
DI
FF
x
Q
MA
IN
LIM SEQLIM
SHIFT
1
CTLOOP 1
DV
A
LM
SE
Q2 Y
SE
Q2 P
SE
Q1 Y
SE
Q1 P
SE
Q4 Y
SE
Q4 P
SE
Q5 Y
SE
Q5 P
p2
PU
M
P 1
PUMP 1
Y
X2
Y
SI
G
N
AL
Y
LABEL
TEMP
y
31
01
S
28
108 / 174
Siemens
Universal Controllers RLU2…
CE1P3101en
Building Technologies
Controller (CTLOOP x)
29.08.2008