Siemens AVS75.39 Series User Manual page 64

Control of mixing valve
Mixing valve boost
Actuator type
Switching differential 2-
pos
Actuator running time
Mixing valve Xp
Mixing valve Tn
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Building Technologies
Line no.
HC1 HC2 HC3
830 1130 1430
832 1132 1432
833 1133 1433
834 1134 1434
835 1135 1435
836 1136 1436
To ensure proper mixing valve flow temperature control, the flow temperature must
be higher than the demanded setpoint of the mixing valve flow temperature. The
controller adds the mixing valve boost set here to the current flow temperature
setpoint and uses the value as the value for heat generation setpoint.
2-position
The controller uses only one relay output to drive the actuator. When the output
delivers a signal, the connected valve opens. When there is no signal, the valve
closes automatically.
3-position
The controller drives the actuator with 2 relay outputs. One output is used for
opening the connected valve, the other for closing it.
For a 2-position actuator, the 2-position switching differential must also be adapted.
This is not required when using a 3-position actuator.
For the 3-position actuator, the running time of the mixing valve actuator can be
adjusted. The actuator running time has no impact on 2-position actuators.
By setting the right proportional band Xp for the mixing valves actuator, the control
behavior of the actuator is matched to those of the plant (controlled system).
The proportional band Xp influences the controller's P-action.
The P band Xp is the range by which the input variable x (controlled variable) must
change to adjust the output variable y (manipulated variable) throughout the entire
positioning range. The smaller the value the greater the jump. The illustration
depicts the reciprocal value 1/Xp = Kp.
By setting the right integral action time Tn, the control action of the mixing valve's
actuator is matched to the behavior of the plant (controlled system).
Tn influences the controller's I-response.
It is the required of the I-portion to undertake the same manipulated variable
change at the given input signal (controlled variable), as immediately provided by
the P-portion. The smaller the Tn the larger/faster the slope.
User manual RVS43.345
The settings in detail
Operating line
Mixing valve boost
Actuator type
2-position ¦ 3-position
Switching differential 2-pos
Actuator running time
Mixing valve Xp
Mixing valve Tn
CE1U2354en_021
2013-09-02