CE1P2522E / 30.03.2000
Basic Documentation RVL470
Siemens Building Technologies
38/68
Function block "Setpoint of return temperature limitation"
Landis & Staefa Division
11.3.3. Mode of operation with a single unit (with no bus)
No facility for min.
limitation of return temp.
25
22
B
0
6e
Setting operating line 101 = 50 °C,
return temp. sensor connected
Controller 1
Boiler controller
Controller 2
Plant type 1
Controller 2 generates a
critical locking signal which
closes the mixing valve
11.3.4. Mode of operation in interconnected plants
11.3.4.1. Central impact of limitation
Controller 1
Plant type 5
Controller 2
Plant type 1
Controller 3
Plant type 1
Critical locking signal
Controller 2 closes
the mixing valve
Controller 3 closes
the mixing valve
LPB
25
22B
0
7
e
Setting operating
line 101 = 50 °C,
return temperature
sensor connected
Critical locking signal
Setting operating line 101 = - - - ,
no own return temp. sensor connected
Setting operating 101 = - - - ,
no own return temp. sensor connected
11.3.4.2. Local impact of limitation
Controller 2
Plant type 1
Controller 3
Plant type 1
Return temperature signal
Controller 2 limits
return temp. to 50 °C
LPB
25
22B
0
8
e
Setting operating line 101 = 50 °C,
return temp. sensor connected
Setting operating line 101 = 40 °C,
no own return temp. sensor connected
Controller 3 limits
return temp. to 40 °C
Controller 1
Boiler controller
(no facility for min.
limitation of return temp.)
The group controller with its own return temperature sensor (plant type 1) passes the re-
turn temperature to the other zone controllers in the same segment, which can provide
minimum limitation of the return temperature on a local basis, depending on the settings
made. This means they generate a critical locking signal internally (for response to criti-
cal locking signals, refer to section "13.4.7. Gain of locking signal").
