9.2.9
Implementation: Room temperature control with supply
air temperature limitation
9.2.9.1
Activating the control process
Room temperature control with supply air temperature limitation can only be
activated for controller 1, basic type A.
Activation for controller
1 only, basic type A
To activate this control strategy, assign one input each to the room and the supply
air temperature and select control strategy LIM.
Also refer to subsection 9.2.1 ”Selecting the control strategy“.
9.2.9.2
Operating principle
PID control maintains the room temperature at the adjusted setpoint. The LIM
function (general limitation function) overrides the sequence controller’s normal
control function to keep the supply air temperature within adjusted limits.
Purpose of LIM
Also refer to section 9.6 “Limitation, general (LIM)“.
If, at the same time, other influences act on the sequence controller, the priority
order according to subsection 9.1.4 “Function priorities” applies.
9.2.9.3
Troubleshooting
When you leave the commissioning menu, the universal controller checks whether
room and supply air temperature sensor are connected and then responds as
follows:
Supply air and room
temperature sensor
present?
•
If, at that time, the measured values of room and supply air temperature are
available, but are missing later, a sensor error message is delivered and
presented on the display:
–
"Xx ---"
=> sensor missing
–
"Xx ooo"
=> short-circuit
•
If, at that time, no supply air temperature sensor is connected, limitation is set
inactive (room temperature control without supply air temperature limitation)
•
If, at that time, no room temperature sensor is connected (main controlled
variable in this case), the plant will be shut down (MAINALM)
103 / 174
Siemens
Universal Controllers RLU2…
CE1P3101en
Building Technologies
Controller (CTLOOP x)
29.08.2008
