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Siemens Building Technologies
Basic Documentation RVP540 / RVP550
CE1P2488en
HVAC Products
Description of the EXP settings
18.10.2002
•
System
pump
Status Effect
Locking signal > 5 %
System pump OFF
Locking signal = 0 %
Normal pump operation
Through the generation of the temperature-time integral it is not only the period of time
that is considered, but also the extent of the undershoot. This means that when the
crossing is significant, the pumps will be deactivated earlier.
5.10.2 Impact on modulating loads
Due to the lowering of the setpoint, heat consumption will be reduced. This reduces
considerably the boiler water's heating up time.
•
Mixing
valve:
Status Effect
Locking signal > 0%
Flow temperature setpoint will be lowered.
The extent of lowering is dependent on the magnitude and
the period of time of boiler temperature undershoot.
Locking signal reduced to
0 %
Setpoint according to the normal control condition
Through the generation of the temperature-time integral it is not only the period of time
that is considered, but also the extent of the undershoot. This means that when the
undershoot is significant, the setpoint reduction will be greater.
Protective boiler startup can be interrupted to ensure that, in the event of a burner fault,
for instance, frost protection for the plant will be provided.
In the case of protective boiler start-up and simultaneous frost protection for the plant,
the boiler temperature gradient must turn positive within 15 minutes. Otherwise, the
locking signal will become invalid for at least 15 minutes. On completion of the 15 min-
utes, protective boiler start-up will become active again as soon as the boiler tempera-
ture gradient turns positive.
5.10.3 Temperature-time integral
The temperature-time integral generates the locking signal for restricting the heating
circuits or boiler pump operation.
During the generation of the locking signal, the following processes can take place:
Diagram Procedure
a to b
Within a foreseeable period of time, the actual boiler temperature (TKx)
will lie
below
the value of Tkmin-SDK/2.
Locking signal will be built up
b to c and
d to e
Within a foreseeable period of time, the actual boiler return temperature
(TKx) will lie within half the switching differential of the boiler tempera-
ture's minimum limitation.
Locking signal will remain at a constant level
c to d and
e to f
Within a foreseeable period of time, the actual boiler temperature (TKx)
will lie
above
TKw.
Locking signal will be decreased
Switching point
Setpoint reduction
Supervision
Description
