Auber Instruments WS Series - Detailed Parameter Explanations; Proportional Band (P); Integral Time (I); Derivative Time (d)

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Table 2 List of control parameters and its initial settings under code 166
Symbol
Display
Description
Range
Initial
P
p
Proportional band
0-600
7
I
I
Integral constant (second)
0-900
600
d
d
Derivative constant (second)
0-300
150
AT
At
Auto-tune
0=off 1=on
0
T
t
Cycle rate (second)
1-100
2
R1
R1
Smoker generator on step 1
0-6
1
R2
R2
Smoker generator on step 2
0-6
0
Details about each parameter
• P. Proportional band. It is in 1 degree units. This parameter controls the output of
the controller based on the difference between the measured and set
temperatures. The larger the P number means the weaker the action (lower gain).
e. g. If P=7, the proportional band is 7 degrees. When the sensor temperature is 7
degrees below the proportional band (7 degrees below the setting), the controller
will have 100% output. When the temperature is 5 degrees below the set point,
the output is 71%. When the temperature is equal to the setting, the controller will
have 0% output (assuming integral and derivative functions are turned off). This
constant also affects both integral and derivative action. Smaller P values will
make both integral and derivative action stronger. Please note the value of the P
is temperature unit sensitive. If you found an optimized P value when operating
the controller in Fahrenheit, you need to divide the P by 1.8 when changing the
temperature unit to Celsius.
• I. Integral time. The unit is in seconds. This parameter controls the output of the
controller based on the difference between the measured and set temperature
integrated with time. Integral action is used to eliminate temperature offset. Larger
number means slower action. e. g. assuming the difference between the
measured and set temperature is 2 degrees and remains unchanged, the output
will increase continuously with time until it reaches 100%. When temperature
fluctuate regularly (system oscillating), increase the integral time. Decrease it if
the controller is taking too long to eliminate the temperature offset. When I=0, the
system becomes a PD controller. For very slow response systems such as slow
cookers and large commercial rice cookers, setting I = 0 will significantly reduce
the temperature overshoot.
• d. Derivative time. The unit is in seconds. Derivative action contributes the output
power based on the rate of temperature change. Derivative action can be used to
minimize the temperature overshoot by responding to its rate of change. The
larger the number is, the faster the action will be. e.g. when the door of an oven is
opened, the temperature will drop at a very high rate. The derivative action
changes the controller output based on the rate of change rather than the net