Siemens AVS75.39 Series User Manual page 99

Minimum limitation of
the return temperature
mixing valve
Mixing valve Xp
Mixing valve Tn
Modulating preheat Tv
Bypass pump
Switching diff bypass
pump
Bypass pump
Control of the bypass
pump
Siemens
Building Technologies
Line no. Operating line
2282 Actuator running time
2283 Mixing valve Xp
2284 Mixing valve Tn
2285 Mixing valve Tv
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.
By setting the right derivative action time, the control action of the mixing valve's
actuator is matched to the behavior of the plant (controlled system).
Tv influences the controller's D-behavior. With Tv = 0, the D-action is deactivated.
Line no. Operating line
2290 Switching diff bypass pump
Control of the bypass pump "according to the boiler return temperature" is in the
form of 2-position control for which a switching differential must be set.
2291 Control bypass pump
Parallel burner operation ¦ Return temp
The boiler bypass pump improves the circulation of water through the boiler, thus
preventing the boiler temperature from falling below a certain level.
Parallel with the operation of the burner
The boiler bypass pump is switched according to the burner's on / off signals.
According to the boiler return temperature
The boiler bypass pump is switched according to the minimum limitation of the
boiler return temperature and the switching differential of the bypass pump.
User manual RVS43.345
The settings in detail
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CE1U2354en_021
2013-09-02