Basic Documentation

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Siemens Universal controllers RMU710B, RMU720B, RMU730B CE1P3150en
Building Technologies Sequence controller 03.10.2011
15.2.2 Operating principle
The limitation function with PI control overrides the normal control function to
adhere to the limitation setpoint when the limitation setpoint is exceeded (up or
down).
Absolute and relative limitation can be entered. If only one of the these functions is
desired, the other function can be deactivated by setting the setpoints far outside.
General limitation, absolute
One setpoint each for maximum and minimum limitation can be entered.
x
w
T
T
[Limit value high]
[Limit value low]
- [Set back]
Limitation max
Limitation min
3140S02en
A
cts an all sequences
Setpoint shift
If cooling sequence 4+5 is active, minimum limitation can be lowered by a set
value. This prevents the refrigeration machine from being switched off again just
after switching on in the case of staged (direct) cooling. This function is only active
if both main controlled variable and input for general limitation use unit °C.
General limitation, relative
The maximum and minimum differential limitation can only be activated if the main
controlled variable and the general limiter are configured with the same unit.
The set limitation setpoints relate to the differential (e.g. temperature) between the
main controlled variable and the general limiter.
t
T [°C]
28 °C
16 °C
Room temperature
3150D22en
limit value high
difference high
difference low
limit value low
shifting limits
A setpoint each for maximum and minimum limitation of the temperature differential
can be entered.
Application example
Special case