14033590.01 10/2014 GB/D
40
WIKA operating instructions model CS4S
GB
If, with a lowering in temperature, there is a greater difference between the set
point and the actual value
Disturbances are generated if the temperature around the set BIAS value (here e.g. 20 °C)
is higher than the set point.
Determining the PID parameters
Parameter determination completed
Controlling with the control parameters
determined through auto tuning
AT BIAS value
Temperature 20 °C higher than the set point
Time
Temper
atur
e
Set point
AT starting time
9.3 Auto reset (Offset correction)
PD control can produce a permanent control deviation (offset) between the actual value
and the set point. The auto-reset function for the correction of the offset will be started
when, with PD control, the actual value stabilises within the proportional band.
The compensation value is stored and it is therefore not necessary to restart the auto-reset
function, so long as the process does not change.
If the proportional band is set to “0”, however, the compensation value will be erased.
Auto reset is carried out
Time
Temper
atur
e
Set point
Offset has been corrected
Offset
9. Control mode
