Pid Control Algorithm - Siemens LMS14 User Manual

P-band Xp
HCs/DHW
Int action time Tn
HCs/DHW
Der action time Tv
HCs/DHW
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Building Technologies Division

6.11.6 PID control algorithm

To parameterize the PID control algorithm, 2 sets of controller coefficients are available.
One set is used for Heating mode, the other for drawing DHW from the instantaneous
water heater or for charging a DHW storage tank (DHW).
Control parameters for Heating mode:
Line no. Operating line
2233 P-band Xp HCs
2234 Int action time Tn HCs
2235 Der action time Tv HCs
Control parameters for DHW mode:
Line no. Operating line
2236 P-band Xp DHW
2237 Int action time Tn DHW
2238 Der action time Tv DHW
Line no. Operating line
2233 P-band Xp HCs
2236 P-band Xp DHW
P-band Xp defines the controller's gain. A small Xp leads to higher burner fan speeds
without changing the control offset T = (temperature setpoint – actual value of
temperature).
Line no. Operating line
2234 Int action time Tn HCs
2237 Int action time Tn DHW
The integral action time Tn defines the controller's rate of response when correcting
proportional offsets. A shorter Tn leads to faster correcting actions.
Line no. Operating line
2235 Der action time Tv HCs
2238 Der action time Tv DHW
The derivative action time Tv determines the extent of after-effect of a spontaneous
change of control offset. A short Tv only has a short-time impact on the manipulated
variable.
User Manual LMS14...
6 The settings in detail
CC1U7471en
07.05.2014