Control Signal; Pump Control And Twin Pumps - Siemens Synco 700 Basic Documentation

Integral action time Tn
Electrothermal actuators
Synchronization
pulse
Building Technologies
HVAC Products
• The control action is too slow.
Decrease P-band Xp in steps of about 25 %
• The control action is too fast.
Increase P-band Xp in steps of about 25 %
The integral action time Tn is indicated in seconds and amounts to about 3 × Tu (also
refer to "Setting rules" above). Tu is impacted by great filter time constants, especially
in the case of fast controlled systems.
The integral action time indicates how long it takes the controller in the event of a
constant temperature deviation to deliver the same valve travel as this would be the
case with the P-part.
For example, an integral action time of 120 seconds means that in the event of a
control deviation of 5 K in the above example (Xp = 40 K), it takes the mixing valve
120 seconds to travel 2 × 12.5 % toward the fully open or fully closed position (12.5 %
due to the P-part and 12.5 % due to the I-part).
If the integral action time is increased, the control system will respond more slowly but
becomes more stable.
5.7.3

Control signal

Since the control algorithm uses a stroke model which does not provide control beyond
0 % and 100 % respectively, the use of electrothermal actuators is no longer possible,
as this was the case with the RVL47... controllers.
For 3-position control, the actuator's current position is acquired by a stroke model. As
soon as the stroke model reaches 0 % or 100 % respectively, a synchronization signal
(continuous on pulse or continuous off pulse for 1.5 times the running time) is delivered
to the actuator, thus making certain it has reached the relevant position.
This synchronization pulse is repeated for one minute at 10-minute intervals.
If a position change is called for, the synchronization pulse will immediately be stopped.
5.8

Pump control and twin pumps

Every pump (main pump, boiler pump, system pump, heating circuit pump) can be
monitored with a flow switch and an associated fault input.
Also, every pump can be a twin pump.
d d d
B
V
B
Q Q
The decision whether the pump to be installed shall be a single or twin pump is made
via "Extra configuration" at the respective function block (heating circuit, DHW, primary
controller, main controller, boiler).
Modular Heating Controller RMH760B
5 General functions, fundamentals
59/238
CE1P3133en
05.02.2007