Siemens SIMATIC S7 - Page 325

Glossary
9–9
IP244
C79000–Y8576–C858–02
Symbols and abbreviations for variables and values
BW Limit value, limits the influence to a secondary setpoint.
F Evaluation factor, value for the influence of the master controller.
HCR Heating-cooling ratio, parameter for balancing different heating
or cooling capacity with three-step controllers.
K
P
Proportional coefficient or gain factor ( = 100/ X
P
)
K
S
Transfer coefficient (control system)
ST
H
Maximum slope when heating
ST
K
Maximum slope when cooling
T
A
Sampling time
T
AK
Sampling time when cooling
T
AZ
Approach time
T
g
Response time (control system)
T
N
Integral action time (describes integral action)
T
NK
Integral action time for cooling
T
U
Delay time (replaces dead time)
T
UH
Delay time when heating
T
UK
Delay time when cooling
T
V
Derivative action time, describes derivative action (also T
D
)
T
VK
Derivative action time for cooling
T
Z
Filter time constant for damping the derivative influence
W
1
Operational setpoint
W
2
Lower setpoint
W
A
Approach setpoint
X
d
System deviation (system difference)
X
P
Proportional band ( = 1/ K
P
)
X
PK
Proportional band for cooling
Y Manipulated variable
Y
H
Manual manipulated variable
Y
A
Response value
Y
AS
Approach manipulated variable
Z
A
Approach zone
ZONOB Zone upper limit, no control above it, manipulated variable at end
or start of area.
ZONUN Zone lower limit, no control below it, manipulated variable at start
or end of area.